Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

322 files changed, 13854 insertions, 0 deletions

diff --git a/dom/media/mediasource/AsyncEventRunner.h b/dom/media/mediasource/AsyncEventRunner.h
new file mode 100644
index 0000000000..37a7a1b6b3
--- /dev/null
+++ b/dom/media/mediasource/AsyncEventRunner.h
@@ -0,0 +1,32 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_ASYNCEVENTRUNNER_H_
+#define MOZILLA_ASYNCEVENTRUNNER_H_
+
+#include "nsThreadUtils.h"
+
+namespace mozilla {
+
+template <typename T>
+class AsyncEventRunner : public Runnable {
+ public:
+  AsyncEventRunner(T* aTarget, const char* aName)
+      : Runnable("AsyncEventRunner"), mTarget(aTarget), mName(aName) {}
+
+  NS_IMETHOD Run() override {
+    mTarget->DispatchSimpleEvent(mName);
+    return NS_OK;
+  }
+
+ private:
+  RefPtr<T> mTarget;
+  const char* mName;
+};
+
+}  // namespace mozilla
+
+#endif /* MOZILLA_ASYNCEVENTRUNNER_H_ */
diff --git a/dom/media/mediasource/ContainerParser.cpp b/dom/media/mediasource/ContainerParser.cpp
new file mode 100644
index 0000000000..b6f86928e9
--- /dev/null
+++ b/dom/media/mediasource/ContainerParser.cpp
@@ -0,0 +1,763 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ContainerParser.h"
+
+#include "WebMBufferedParser.h"
+#include "mozilla/EndianUtils.h"
+#include "mozilla/IntegerPrintfMacros.h"
+#include "mozilla/ErrorResult.h"
+#include "MoofParser.h"
+#include "mozilla/Logging.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/Result.h"
+#include "MediaData.h"
+#include "nsMimeTypes.h"
+#ifdef MOZ_FMP4
+#  include "AtomType.h"
+#  include "BufferReader.h"
+#  include "Index.h"
+#  include "MP4Interval.h"
+#  include "ByteStream.h"
+#endif
+#include "SourceBufferResource.h"
+#include <algorithm>
+
+extern mozilla::LogModule* GetMediaSourceSamplesLog();
+
+#define MSE_DEBUG(arg, ...)                                            \
+  DDMOZ_LOG(GetMediaSourceSamplesLog(), mozilla::LogLevel::Debug,      \
+            "(%s)::%s: " arg, mType.OriginalString().Data(), __func__, \
+            ##__VA_ARGS__)
+#define MSE_DEBUGV(arg, ...)                                           \
+  DDMOZ_LOG(GetMediaSourceSamplesLog(), mozilla::LogLevel::Verbose,    \
+            "(%s)::%s: " arg, mType.OriginalString().Data(), __func__, \
+            ##__VA_ARGS__)
+#define MSE_DEBUGVEX(_this, arg, ...)                                        \
+  DDMOZ_LOGEX(_this, GetMediaSourceSamplesLog(), mozilla::LogLevel::Verbose, \
+              "(%s)::%s: " arg, mType.OriginalString().Data(), __func__,     \
+              ##__VA_ARGS__)
+
+namespace mozilla {
+
+ContainerParser::ContainerParser(const MediaContainerType& aType)
+    : mHasInitData(false), mTotalParsed(0), mGlobalOffset(0), mType(aType) {}
+
+ContainerParser::~ContainerParser() = default;
+
+MediaResult ContainerParser::IsInitSegmentPresent(const MediaSpan& aData) {
+  MSE_DEBUG(
+      "aLength=%zu [%x%x%x%x]", aData.Length(),
+      aData.Length() > 0 ? aData[0] : 0, aData.Length() > 1 ? aData[1] : 0,
+      aData.Length() > 2 ? aData[2] : 0, aData.Length() > 3 ? aData[3] : 0);
+  return NS_ERROR_NOT_AVAILABLE;
+}
+
+MediaResult ContainerParser::IsMediaSegmentPresent(const MediaSpan& aData) {
+  MSE_DEBUG(
+      "aLength=%zu [%x%x%x%x]", aData.Length(),
+      aData.Length() > 0 ? aData[0] : 0, aData.Length() > 1 ? aData[1] : 0,
+      aData.Length() > 2 ? aData[2] : 0, aData.Length() > 3 ? aData[3] : 0);
+  return NS_ERROR_NOT_AVAILABLE;
+}
+
+MediaResult ContainerParser::ParseStartAndEndTimestamps(const MediaSpan& aData,
+                                                        int64_t& aStart,
+                                                        int64_t& aEnd) {
+  return NS_ERROR_NOT_AVAILABLE;
+}
+
+bool ContainerParser::TimestampsFuzzyEqual(int64_t aLhs, int64_t aRhs) {
+  return llabs(aLhs - aRhs) <= GetRoundingError();
+}
+
+int64_t ContainerParser::GetRoundingError() {
+  NS_WARNING("Using default ContainerParser::GetRoundingError implementation");
+  return 0;
+}
+
+bool ContainerParser::HasCompleteInitData() {
+  return mHasInitData && !!mInitData->Length();
+}
+
+MediaByteBuffer* ContainerParser::InitData() { return mInitData; }
+
+MediaByteRange ContainerParser::InitSegmentRange() {
+  return mCompleteInitSegmentRange;
+}
+
+MediaByteRange ContainerParser::MediaHeaderRange() {
+  return mCompleteMediaHeaderRange;
+}
+
+MediaByteRange ContainerParser::MediaSegmentRange() {
+  return mCompleteMediaSegmentRange;
+}
+
+DDLoggedTypeDeclNameAndBase(WebMContainerParser, ContainerParser);
+
+class WebMContainerParser
+    : public ContainerParser,
+      public DecoderDoctorLifeLogger<WebMContainerParser> {
+ public:
+  explicit WebMContainerParser(const MediaContainerType& aType)
+      : ContainerParser(aType), mParser(0), mOffset(0) {}
+
+  static const unsigned NS_PER_USEC = 1000;
+
+  MediaResult IsInitSegmentPresent(const MediaSpan& aData) override {
+    ContainerParser::IsInitSegmentPresent(aData);
+    if (aData.Length() < 4) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+
+    WebMBufferedParser parser(0);
+    nsTArray<WebMTimeDataOffset> mapping;
+    if (auto result = parser.Append(aData.Elements(), aData.Length(), mapping);
+        NS_FAILED(result)) {
+      return result;
+    }
+    return parser.mInitEndOffset > 0 ? NS_OK : NS_ERROR_NOT_AVAILABLE;
+  }
+
+  MediaResult IsMediaSegmentPresent(const MediaSpan& aData) override {
+    ContainerParser::IsMediaSegmentPresent(aData);
+    if (aData.Length() < 4) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+
+    WebMBufferedParser parser(0);
+    nsTArray<WebMTimeDataOffset> mapping;
+    parser.AppendMediaSegmentOnly();
+    if (auto result = parser.Append(aData.Elements(), aData.Length(), mapping);
+        NS_FAILED(result)) {
+      return result;
+    }
+    return parser.GetClusterOffset() >= 0 ? NS_OK : NS_ERROR_NOT_AVAILABLE;
+  }
+
+  MediaResult ParseStartAndEndTimestamps(const MediaSpan& aData,
+                                         int64_t& aStart,
+                                         int64_t& aEnd) override {
+    bool initSegment = NS_SUCCEEDED(IsInitSegmentPresent(aData));
+
+    if (mLastMapping &&
+        (initSegment || NS_SUCCEEDED(IsMediaSegmentPresent(aData)))) {
+      // The last data contained a complete cluster but we can only detect it
+      // now that a new one is starting.
+      // We use mOffset as end position to ensure that any blocks not reported
+      // by WebMBufferParser are properly skipped.
+      mCompleteMediaSegmentRange =
+          MediaByteRange(mLastMapping.ref().mSyncOffset, mOffset) +
+          mGlobalOffset;
+      mLastMapping.reset();
+      MSE_DEBUG("New cluster found at start, ending previous one");
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+
+    if (initSegment) {
+      mOffset = 0;
+      mParser = WebMBufferedParser(0);
+      mOverlappedMapping.Clear();
+      mInitData = new MediaByteBuffer();
+      mResource = new SourceBufferResource();
+      DDLINKCHILD("resource", mResource.get());
+      mCompleteInitSegmentRange = MediaByteRange();
+      mCompleteMediaHeaderRange = MediaByteRange();
+      mCompleteMediaSegmentRange = MediaByteRange();
+      mGlobalOffset = mTotalParsed;
+    }
+
+    // XXX if it only adds new mappings, overlapped but not available
+    // (e.g. overlap < 0) frames are "lost" from the reported mappings here.
+    nsTArray<WebMTimeDataOffset> mapping;
+    mapping.AppendElements(mOverlappedMapping);
+    mOverlappedMapping.Clear();
+    if (auto result = mParser.Append(aData.Elements(), aData.Length(), mapping);
+        NS_FAILED(result)) {
+      return result;
+    }
+    if (mResource) {
+      mResource->AppendData(aData);
+    }
+
+    // XXX This is a bit of a hack.  Assume if there are no timecodes
+    // present and it's an init segment that it's _just_ an init segment.
+    // We should be more precise.
+    if (initSegment || !HasCompleteInitData()) {
+      if (mParser.mInitEndOffset > 0) {
+        MOZ_DIAGNOSTIC_ASSERT(mInitData && mResource &&
+                              mParser.mInitEndOffset <= mResource->GetLength());
+        if (!mInitData->SetLength(mParser.mInitEndOffset, fallible)) {
+          // Super unlikely OOM
+          return NS_ERROR_OUT_OF_MEMORY;
+        }
+        mCompleteInitSegmentRange =
+            MediaByteRange(0, mParser.mInitEndOffset) + mGlobalOffset;
+        char* buffer = reinterpret_cast<char*>(mInitData->Elements());
+        mResource->ReadFromCache(buffer, 0, mParser.mInitEndOffset);
+        MSE_DEBUG("Stashed init of %" PRId64 " bytes.", mParser.mInitEndOffset);
+        mResource = nullptr;
+      } else {
+        MSE_DEBUG("Incomplete init found.");
+      }
+      mHasInitData = true;
+    }
+    mOffset += aData.Length();
+    mTotalParsed += aData.Length();
+
+    if (mapping.IsEmpty()) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+
+    // Calculate media range for first media segment.
+
+    // Check if we have a cluster finishing in the current data.
+    uint32_t endIdx = mapping.Length() - 1;
+    bool foundNewCluster = false;
+    while (mapping[0].mSyncOffset != mapping[endIdx].mSyncOffset) {
+      endIdx -= 1;
+      foundNewCluster = true;
+    }
+
+    int32_t completeIdx = endIdx;
+    while (completeIdx >= 0 && mOffset < mapping[completeIdx].mEndOffset) {
+      MSE_DEBUG("block is incomplete, missing: %" PRId64,
+                mapping[completeIdx].mEndOffset - mOffset);
+      completeIdx -= 1;
+    }
+
+    // Save parsed blocks for which we do not have all data yet.
+    mOverlappedMapping.AppendElements(mapping.Elements() + completeIdx + 1,
+                                      mapping.Length() - completeIdx - 1);
+
+    if (completeIdx < 0) {
+      mLastMapping.reset();
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+
+    if (mCompleteMediaHeaderRange.IsEmpty()) {
+      mCompleteMediaHeaderRange =
+          MediaByteRange(mapping[0].mSyncOffset, mapping[0].mEndOffset) +
+          mGlobalOffset;
+    }
+
+    if (foundNewCluster && mOffset >= mapping[endIdx].mEndOffset) {
+      // We now have all information required to delimit a complete cluster.
+      int64_t endOffset = mapping[endIdx + 1].mSyncOffset;
+      if (mapping[endIdx + 1].mInitOffset > mapping[endIdx].mInitOffset) {
+        // We have a new init segment before this cluster.
+        endOffset = mapping[endIdx + 1].mInitOffset;
+      }
+      mCompleteMediaSegmentRange =
+          MediaByteRange(mapping[endIdx].mSyncOffset, endOffset) +
+          mGlobalOffset;
+    } else if (mapping[endIdx].mClusterEndOffset >= 0 &&
+               mOffset >= mapping[endIdx].mClusterEndOffset) {
+      mCompleteMediaSegmentRange =
+          MediaByteRange(
+              mapping[endIdx].mSyncOffset,
+              mParser.EndSegmentOffset(mapping[endIdx].mClusterEndOffset)) +
+          mGlobalOffset;
+    }
+
+    Maybe<WebMTimeDataOffset> previousMapping;
+    if (completeIdx) {
+      previousMapping = Some(mapping[completeIdx - 1]);
+    } else {
+      previousMapping = mLastMapping;
+    }
+
+    mLastMapping = Some(mapping[completeIdx]);
+
+    if (!previousMapping && completeIdx + 1u >= mapping.Length()) {
+      // We have no previous nor next block available,
+      // so we can't estimate this block's duration.
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+
+    uint64_t frameDuration =
+        (completeIdx + 1u < mapping.Length())
+            ? mapping[completeIdx + 1].mTimecode -
+                  mapping[completeIdx].mTimecode
+            : mapping[completeIdx].mTimecode - previousMapping.ref().mTimecode;
+    aStart = mapping[0].mTimecode / NS_PER_USEC;
+    aEnd = (mapping[completeIdx].mTimecode + frameDuration) / NS_PER_USEC;
+
+    MSE_DEBUG("[%" PRId64 ", %" PRId64 "] [fso=%" PRId64 ", leo=%" PRId64
+              ", l=%zu processedIdx=%u fs=%" PRId64 "]",
+              aStart, aEnd, mapping[0].mSyncOffset,
+              mapping[completeIdx].mEndOffset, mapping.Length(), completeIdx,
+              mCompleteMediaSegmentRange.mEnd);
+
+    return NS_OK;
+  }
+
+  int64_t GetRoundingError() override {
+    int64_t error = mParser.GetTimecodeScale() / NS_PER_USEC;
+    return error * 2;
+  }
+
+ private:
+  WebMBufferedParser mParser;
+  nsTArray<WebMTimeDataOffset> mOverlappedMapping;
+  int64_t mOffset;
+  Maybe<WebMTimeDataOffset> mLastMapping;
+};
+
+#ifdef MOZ_FMP4
+
+DDLoggedTypeDeclNameAndBase(MP4Stream, ByteStream);
+
+class MP4Stream : public ByteStream, public DecoderDoctorLifeLogger<MP4Stream> {
+ public:
+  explicit MP4Stream(SourceBufferResource* aResource);
+  virtual ~MP4Stream();
+  bool ReadAt(int64_t aOffset, void* aBuffer, size_t aCount,
+              size_t* aBytesRead) override;
+  bool CachedReadAt(int64_t aOffset, void* aBuffer, size_t aCount,
+                    size_t* aBytesRead) override;
+  bool Length(int64_t* aSize) override;
+  const uint8_t* GetContiguousAccess(int64_t aOffset, size_t aSize) override;
+
+ private:
+  RefPtr<SourceBufferResource> mResource;
+};
+
+MP4Stream::MP4Stream(SourceBufferResource* aResource) : mResource(aResource) {
+  MOZ_COUNT_CTOR(MP4Stream);
+  MOZ_ASSERT(aResource);
+  DDLINKCHILD("resource", aResource);
+}
+
+MP4Stream::~MP4Stream() { MOZ_COUNT_DTOR(MP4Stream); }
+
+bool MP4Stream::ReadAt(int64_t aOffset, void* aBuffer, size_t aCount,
+                       size_t* aBytesRead) {
+  return CachedReadAt(aOffset, aBuffer, aCount, aBytesRead);
+}
+
+bool MP4Stream::CachedReadAt(int64_t aOffset, void* aBuffer, size_t aCount,
+                             size_t* aBytesRead) {
+  nsresult rv = mResource->ReadFromCache(reinterpret_cast<char*>(aBuffer),
+                                         aOffset, aCount);
+  if (NS_FAILED(rv)) {
+    *aBytesRead = 0;
+    return false;
+  }
+  *aBytesRead = aCount;
+  return true;
+}
+
+const uint8_t* MP4Stream::GetContiguousAccess(int64_t aOffset, size_t aSize) {
+  return mResource->GetContiguousAccess(aOffset, aSize);
+}
+
+bool MP4Stream::Length(int64_t* aSize) {
+  if (mResource->GetLength() < 0) return false;
+  *aSize = mResource->GetLength();
+  return true;
+}
+
+DDLoggedTypeDeclNameAndBase(MP4ContainerParser, ContainerParser);
+
+class MP4ContainerParser : public ContainerParser,
+                           public DecoderDoctorLifeLogger<MP4ContainerParser> {
+ public:
+  explicit MP4ContainerParser(const MediaContainerType& aType)
+      : ContainerParser(aType) {}
+
+  MediaResult IsInitSegmentPresent(const MediaSpan& aData) override {
+    ContainerParser::IsInitSegmentPresent(aData);
+    // Each MP4 atom has a chunk size and chunk type. The root chunk in an MP4
+    // file is the 'ftyp' atom followed by a file type. We just check for a
+    // vaguely valid 'ftyp' atom.
+    if (aData.Length() < 8) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+    AtomParser parser(*this, aData, AtomParser::StopAt::eInitSegment);
+    if (!parser.IsValid()) {
+      return MediaResult(
+          NS_ERROR_FAILURE,
+          RESULT_DETAIL("Invalid Top-Level Box:%s", parser.LastInvalidBox()));
+    }
+    return parser.StartWithInitSegment() ? NS_OK : NS_ERROR_NOT_AVAILABLE;
+  }
+
+  MediaResult IsMediaSegmentPresent(const MediaSpan& aData) override {
+    if (aData.Length() < 8) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+    AtomParser parser(*this, aData, AtomParser::StopAt::eMediaSegment);
+    if (!parser.IsValid()) {
+      return MediaResult(
+          NS_ERROR_FAILURE,
+          RESULT_DETAIL("Invalid Box:%s", parser.LastInvalidBox()));
+    }
+    return parser.StartWithMediaSegment() ? NS_OK : NS_ERROR_NOT_AVAILABLE;
+  }
+
+ private:
+  class AtomParser {
+   public:
+    enum class StopAt { eInitSegment, eMediaSegment, eEnd };
+
+    AtomParser(const MP4ContainerParser& aParser, const MediaSpan& aData,
+               StopAt aStop = StopAt::eEnd) {
+      mValid = Init(aParser, aData, aStop).isOk();
+    }
+
+    Result<Ok, nsresult> Init(const MP4ContainerParser& aParser,
+                              const MediaSpan& aData, StopAt aStop) {
+      const MediaContainerType mType(
+          aParser.ContainerType());  // for logging macro.
+      BufferReader reader(aData);
+      AtomType initAtom("moov");
+      AtomType mediaAtom("moof");
+      AtomType dataAtom("mdat");
+
+      // Valid top-level boxes defined in ISO/IEC 14496-12 (Table 1)
+      static const AtomType validBoxes[] = {
+          "ftyp", "moov",          // init segment
+          "pdin", "free", "sidx",  // optional prior moov box
+          "styp", "moof", "mdat",  // media segment
+          "mfra", "skip", "meta", "meco", "ssix", "prft",  // others.
+          "pssh",         // optional with encrypted EME, though ignored.
+          "emsg",         // ISO23009-1:2014 Section 5.10.3.3
+          "bloc", "uuid"  // boxes accepted by chrome.
+      };
+
+      while (reader.Remaining() >= 8) {
+        uint32_t tmp;
+        MOZ_TRY_VAR(tmp, reader.ReadU32());
+        uint64_t size = tmp;
+        const uint8_t* typec = reader.Peek(4);
+        MOZ_TRY_VAR(tmp, reader.ReadU32());
+        AtomType type(tmp);
+        MSE_DEBUGVEX(&aParser, "Checking atom:'%c%c%c%c' @ %u", typec[0],
+                     typec[1], typec[2], typec[3],
+                     (uint32_t)reader.Offset() - 8);
+        if (std::find(std::begin(validBoxes), std::end(validBoxes), type) ==
+            std::end(validBoxes)) {
+          // No valid box found, no point continuing.
+          mLastInvalidBox[0] = typec[0];
+          mLastInvalidBox[1] = typec[1];
+          mLastInvalidBox[2] = typec[2];
+          mLastInvalidBox[3] = typec[3];
+          mLastInvalidBox[4] = '\0';
+          return Err(NS_ERROR_FAILURE);
+        }
+        if (mInitOffset.isNothing() && AtomType(type) == initAtom) {
+          mInitOffset = Some(reader.Offset());
+        }
+        if (mMediaOffset.isNothing() && AtomType(type) == mediaAtom) {
+          mMediaOffset = Some(reader.Offset());
+        }
+        if (mDataOffset.isNothing() && AtomType(type) == dataAtom) {
+          mDataOffset = Some(reader.Offset());
+        }
+        if (size == 1) {
+          // 64 bits size.
+          MOZ_TRY_VAR(size, reader.ReadU64());
+        } else if (size == 0) {
+          // Atom extends to the end of the buffer, it can't have what we're
+          // looking for.
+          break;
+        }
+        if (reader.Remaining() < size - 8) {
+          // Incomplete atom.
+          break;
+        }
+        reader.Read(size - 8);
+
+        if (aStop == StopAt::eInitSegment && (mInitOffset || mMediaOffset)) {
+          // When we're looking for an init segment, if we encountered a media
+          // segment, it we will need to be processed first. So we can stop
+          // right away if we have found a media segment.
+          break;
+        }
+        if (aStop == StopAt::eMediaSegment &&
+            (mInitOffset || (mMediaOffset && mDataOffset))) {
+          // When we're looking for a media segment, if we encountered an init
+          // segment, it we will need to be processed first. So we can stop
+          // right away if we have found an init segment.
+          break;
+        }
+      }
+
+      return Ok();
+    }
+
+    bool StartWithInitSegment() const {
+      return mInitOffset.isSome() && (mMediaOffset.isNothing() ||
+                                      mInitOffset.ref() < mMediaOffset.ref());
+    }
+    bool StartWithMediaSegment() const {
+      return mMediaOffset.isSome() && (mInitOffset.isNothing() ||
+                                       mMediaOffset.ref() < mInitOffset.ref());
+    }
+    bool IsValid() const { return mValid; }
+    const char* LastInvalidBox() const { return mLastInvalidBox; }
+
+   private:
+    Maybe<size_t> mInitOffset;
+    Maybe<size_t> mMediaOffset;
+    Maybe<size_t> mDataOffset;
+    bool mValid;
+    char mLastInvalidBox[5];
+  };
+
+ public:
+  MediaResult ParseStartAndEndTimestamps(const MediaSpan& aData,
+                                         int64_t& aStart,
+                                         int64_t& aEnd) override {
+    bool initSegment = NS_SUCCEEDED(IsInitSegmentPresent(aData));
+    if (initSegment) {
+      mResource = new SourceBufferResource();
+      DDLINKCHILD("resource", mResource.get());
+      mStream = new MP4Stream(mResource);
+      // We use a timestampOffset of 0 for ContainerParser, and require
+      // consumers of ParseStartAndEndTimestamps to add their timestamp offset
+      // manually. This allows the ContainerParser to be shared across different
+      // timestampOffsets.
+      mParser = MakeUnique<MoofParser>(mStream, AsVariant(ParseAllTracks{}),
+                                       /* aIsAudio = */ false);
+      DDLINKCHILD("parser", mParser.get());
+      mInitData = new MediaByteBuffer();
+      mCompleteInitSegmentRange = MediaByteRange();
+      mCompleteMediaHeaderRange = MediaByteRange();
+      mCompleteMediaSegmentRange = MediaByteRange();
+      mGlobalOffset = mTotalParsed;
+    } else if (!mStream || !mParser) {
+      mTotalParsed += aData.Length();
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+
+    MOZ_DIAGNOSTIC_ASSERT(mResource && mParser && mInitData,
+                          "Should have received an init segment first");
+
+    mResource->AppendData(aData);
+    MediaByteRangeSet byteRanges;
+    byteRanges +=
+        MediaByteRange(int64_t(mParser->mOffset), mResource->GetLength());
+    mParser->RebuildFragmentedIndex(byteRanges);
+
+    if (initSegment || !HasCompleteInitData()) {
+      MediaByteRange& range = mParser->mInitRange;
+      if (range.Length()) {
+        mCompleteInitSegmentRange = range + mGlobalOffset;
+        if (!mInitData->SetLength(range.Length(), fallible)) {
+          // Super unlikely OOM
+          return NS_ERROR_OUT_OF_MEMORY;
+        }
+        char* buffer = reinterpret_cast<char*>(mInitData->Elements());
+        mResource->ReadFromCache(buffer, range.mStart, range.Length());
+        MSE_DEBUG("Stashed init of %" PRIu64 " bytes.", range.Length());
+      } else {
+        MSE_DEBUG("Incomplete init found.");
+      }
+      mHasInitData = true;
+    }
+    mTotalParsed += aData.Length();
+
+    MP4Interval<Microseconds> compositionRange =
+        mParser->GetCompositionRange(byteRanges);
+
+    mCompleteMediaHeaderRange =
+        mParser->FirstCompleteMediaHeader() + mGlobalOffset;
+    mCompleteMediaSegmentRange =
+        mParser->FirstCompleteMediaSegment() + mGlobalOffset;
+
+    if (HasCompleteInitData()) {
+      mResource->EvictData(mParser->mOffset, mParser->mOffset);
+    }
+
+    if (compositionRange.IsNull()) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+    aStart = compositionRange.start;
+    aEnd = compositionRange.end;
+    MSE_DEBUG("[%" PRId64 ", %" PRId64 "]", aStart, aEnd);
+    return NS_OK;
+  }
+
+  // Gaps of up to 35ms (marginally longer than a single frame at 30fps) are
+  // considered to be sequential frames.
+  int64_t GetRoundingError() override { return 35000; }
+
+ private:
+  RefPtr<MP4Stream> mStream;
+  UniquePtr<MoofParser> mParser;
+};
+#endif  // MOZ_FMP4
+
+#ifdef MOZ_FMP4
+DDLoggedTypeDeclNameAndBase(ADTSContainerParser, ContainerParser);
+
+class ADTSContainerParser
+    : public ContainerParser,
+      public DecoderDoctorLifeLogger<ADTSContainerParser> {
+ public:
+  explicit ADTSContainerParser(const MediaContainerType& aType)
+      : ContainerParser(aType) {}
+
+  typedef struct {
+    size_t header_length;  // Length of just the initialization data.
+    size_t frame_length;   // Includes header_length;
+    uint8_t aac_frames;    // Number of AAC frames in the ADTS frame.
+    bool have_crc;
+  } Header;
+
+  /// Helper to parse the ADTS header, returning data we care about.
+  /// Returns true if the header is parsed successfully.
+  /// Returns false if the header is invalid or incomplete,
+  /// without modifying the passed-in Header object.
+  bool Parse(const MediaSpan& aData, Header& header) {
+    // ADTS initialization segments are just the packet header.
+    if (aData.Length() < 7) {
+      MSE_DEBUG("buffer too short for header.");
+      return false;
+    }
+    // Check 0xfffx sync word plus layer 0.
+    if ((aData[0] != 0xff) || ((aData[1] & 0xf6) != 0xf0)) {
+      MSE_DEBUG("no syncword.");
+      return false;
+    }
+    bool have_crc = !(aData[1] & 0x01);
+    if (have_crc && aData.Length() < 9) {
+      MSE_DEBUG("buffer too short for header with crc.");
+      return false;
+    }
+    uint8_t frequency_index = (aData[2] & 0x3c) >> 2;
+    MOZ_ASSERT(frequency_index < 16);
+    if (frequency_index == 15) {
+      MSE_DEBUG("explicit frequency disallowed.");
+      return false;
+    }
+    size_t header_length = have_crc ? 9 : 7;
+    size_t data_length = ((aData[3] & 0x03) << 11) | ((aData[4] & 0xff) << 3) |
+                         ((aData[5] & 0xe0) >> 5);
+    uint8_t frames = (aData[6] & 0x03) + 1;
+    MOZ_ASSERT(frames > 0);
+    MOZ_ASSERT(frames < 4);
+
+    // Return successfully parsed data.
+    header.header_length = header_length;
+    header.frame_length = header_length + data_length;
+    header.aac_frames = frames;
+    header.have_crc = have_crc;
+    return true;
+  }
+
+  MediaResult IsInitSegmentPresent(const MediaSpan& aData) override {
+    // Call superclass for logging.
+    ContainerParser::IsInitSegmentPresent(aData);
+
+    Header header;
+    if (!Parse(aData, header)) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+
+    MSE_DEBUGV("%llu byte frame %d aac frames%s",
+               (unsigned long long)header.frame_length, (int)header.aac_frames,
+               header.have_crc ? " crc" : "");
+
+    return NS_OK;
+  }
+
+  MediaResult IsMediaSegmentPresent(const MediaSpan& aData) override {
+    // Call superclass for logging.
+    ContainerParser::IsMediaSegmentPresent(aData);
+
+    // Make sure we have a header so we know how long the frame is.
+    // NB this assumes the media segment buffer starts with an
+    // initialization segment. Since every frame has an ADTS header
+    // this is a normal place to divide packets, but we can re-parse
+    // mInitData if we need to handle separate media segments.
+    Header header;
+    if (!Parse(aData, header)) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+    // We're supposed to return true as long as aData contains the
+    // start of a media segment, whether or not it's complete. So
+    // return true if we have any data beyond the header.
+    if (aData.Length() <= header.header_length) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+
+    // We should have at least a partial frame.
+    return NS_OK;
+  }
+
+  MediaResult ParseStartAndEndTimestamps(const MediaSpan& aData,
+                                         int64_t& aStart,
+                                         int64_t& aEnd) override {
+    // ADTS header.
+    Header header;
+    if (!Parse(aData, header)) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+    mHasInitData = true;
+    mCompleteInitSegmentRange =
+        MediaByteRange(0, int64_t(header.header_length));
+
+    // Cache raw header in case the caller wants a copy.
+    mInitData = new MediaByteBuffer(header.header_length);
+    mInitData->AppendElements(aData.Elements(), header.header_length);
+
+    // Check that we have enough data for the frame body.
+    if (aData.Length() < header.frame_length) {
+      MSE_DEBUGV(
+          "Not enough data for %llu byte frame"
+          " in %llu byte buffer.",
+          (unsigned long long)header.frame_length,
+          (unsigned long long)(aData.Length()));
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+    mCompleteMediaSegmentRange =
+        MediaByteRange(header.header_length, header.frame_length);
+    // The ADTS MediaSource Byte Stream Format document doesn't
+    // define media header. Just treat it the same as the whole
+    // media segment.
+    mCompleteMediaHeaderRange = mCompleteMediaSegmentRange;
+
+    MSE_DEBUG("[%" PRId64 ", %" PRId64 "]", aStart, aEnd);
+    // We don't update timestamps, regardless.
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  // Audio shouldn't have gaps.
+  // Especially when we generate the timestamps ourselves.
+  int64_t GetRoundingError() override { return 0; }
+};
+#endif  // MOZ_FMP4
+
+/*static*/
+UniquePtr<ContainerParser> ContainerParser::CreateForMIMEType(
+    const MediaContainerType& aType) {
+  if (aType.Type() == MEDIAMIMETYPE(VIDEO_WEBM) ||
+      aType.Type() == MEDIAMIMETYPE(AUDIO_WEBM)) {
+    return MakeUnique<WebMContainerParser>(aType);
+  }
+
+#ifdef MOZ_FMP4
+  if (aType.Type() == MEDIAMIMETYPE(VIDEO_MP4) ||
+      aType.Type() == MEDIAMIMETYPE(AUDIO_MP4)) {
+    return MakeUnique<MP4ContainerParser>(aType);
+  }
+  if (aType.Type() == MEDIAMIMETYPE("audio/aac")) {
+    return MakeUnique<ADTSContainerParser>(aType);
+  }
+#endif
+
+  return MakeUnique<ContainerParser>(aType);
+}
+
+#undef MSE_DEBUG
+#undef MSE_DEBUGV
+#undef MSE_DEBUGVEX
+
+}  // namespace mozilla
diff --git a/dom/media/mediasource/ContainerParser.h b/dom/media/mediasource/ContainerParser.h
new file mode 100644
index 0000000000..98102d195a
--- /dev/null
+++ b/dom/media/mediasource/ContainerParser.h
@@ -0,0 +1,97 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_CONTAINERPARSER_H_
+#define MOZILLA_CONTAINERPARSER_H_
+
+#include "mozilla/RefPtr.h"
+#include "mozilla/UniquePtr.h"
+#include "MediaSpan.h"
+#include "MediaContainerType.h"
+#include "MediaResource.h"
+#include "MediaResult.h"
+
+namespace mozilla {
+
+class MediaByteBuffer;
+class SourceBufferResource;
+
+DDLoggedTypeDeclName(ContainerParser);
+
+class ContainerParser : public DecoderDoctorLifeLogger<ContainerParser> {
+ public:
+  explicit ContainerParser(const MediaContainerType& aType);
+  virtual ~ContainerParser();
+
+  // Return true if aData starts with an initialization segment.
+  // The base implementation exists only for debug logging and is expected
+  // to be called first from the overriding implementation.
+  // Return NS_OK if segment is present, NS_ERROR_NOT_AVAILABLE if no sufficient
+  // data is currently available to make a determination. Any other value
+  // indicates an error.
+  virtual MediaResult IsInitSegmentPresent(const MediaSpan& aData);
+
+  // Return true if aData starts with a media segment.
+  // The base implementation exists only for debug logging and is expected
+  // to be called first from the overriding implementation.
+  // Return NS_OK if segment is present, NS_ERROR_NOT_AVAILABLE if no sufficient
+  // data is currently available to make a determination. Any other value
+  // indicates an error.
+  virtual MediaResult IsMediaSegmentPresent(const MediaSpan& aData);
+
+  // Parse aData to extract the start and end frame times from the media
+  // segment.  aData may not start on a parser sync boundary.  Return NS_OK
+  // if aStart and aEnd have been updated and NS_ERROR_NOT_AVAILABLE otherwise
+  // when no error were encountered.
+  virtual MediaResult ParseStartAndEndTimestamps(const MediaSpan& aData,
+                                                 int64_t& aStart,
+                                                 int64_t& aEnd);
+
+  // Compare aLhs and rHs, considering any error that may exist in the
+  // timestamps from the format's base representation.  Return true if aLhs
+  // == aRhs within the error epsilon.
+  bool TimestampsFuzzyEqual(int64_t aLhs, int64_t aRhs);
+
+  virtual int64_t GetRoundingError();
+
+  MediaByteBuffer* InitData();
+
+  bool HasInitData() { return mHasInitData; }
+
+  // Return true if a complete initialization segment has been passed
+  // to ParseStartAndEndTimestamps(). The calls below to retrieve
+  // MediaByteRanges will be valid from when this call first succeeds.
+  bool HasCompleteInitData();
+  // Returns the byte range of the first complete init segment, or an empty
+  // range if not complete.
+  MediaByteRange InitSegmentRange();
+  // Returns the byte range of the first complete media segment header,
+  // or an empty range if not complete.
+  MediaByteRange MediaHeaderRange();
+  // Returns the byte range of the first complete media segment or an empty
+  // range if not complete.
+  MediaByteRange MediaSegmentRange();
+
+  static UniquePtr<ContainerParser> CreateForMIMEType(
+      const MediaContainerType& aType);
+
+  const MediaContainerType& ContainerType() const { return mType; }
+
+ protected:
+  RefPtr<MediaByteBuffer> mInitData;
+  RefPtr<SourceBufferResource> mResource;
+  bool mHasInitData;
+  uint64_t mTotalParsed;
+  uint64_t mGlobalOffset;
+  MediaByteRange mCompleteInitSegmentRange;
+  MediaByteRange mCompleteMediaHeaderRange;
+  MediaByteRange mCompleteMediaSegmentRange;
+  const MediaContainerType mType;
+};
+
+}  // namespace mozilla
+
+#endif /* MOZILLA_CONTAINERPARSER_H_ */
diff --git a/dom/media/mediasource/MediaSource.cpp b/dom/media/mediasource/MediaSource.cpp
new file mode 100644
index 0000000000..79c8d737c6
--- /dev/null
+++ b/dom/media/mediasource/MediaSource.cpp
@@ -0,0 +1,669 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "MediaSource.h"
+
+#include "AsyncEventRunner.h"
+#include "Benchmark.h"
+#include "DecoderDoctorDiagnostics.h"
+#include "DecoderTraits.h"
+#include "MediaContainerType.h"
+#include "MediaResult.h"
+#include "MediaSourceDemuxer.h"
+#include "MediaSourceUtils.h"
+#include "SourceBuffer.h"
+#include "SourceBufferList.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/FloatingPoint.h"
+#include "mozilla/Logging.h"
+#include "mozilla/Sprintf.h"
+#include "mozilla/StaticPrefs_media.h"
+#include "mozilla/dom/BindingDeclarations.h"
+#include "mozilla/dom/HTMLMediaElement.h"
+#include "mozilla/gfx/gfxVars.h"
+#include "mozilla/mozalloc.h"
+#include "nsDebug.h"
+#include "nsError.h"
+#include "nsIRunnable.h"
+#include "nsIScriptObjectPrincipal.h"
+#include "nsMimeTypes.h"
+#include "nsPIDOMWindow.h"
+#include "nsServiceManagerUtils.h"
+#include "nsString.h"
+#include "nsThreadUtils.h"
+
+#ifdef MOZ_WIDGET_ANDROID
+#  include "AndroidBridge.h"
+#  include "mozilla/java/HardwareCodecCapabilityUtilsWrappers.h"
+#endif
+
+struct JSContext;
+class JSObject;
+
+mozilla::LogModule* GetMediaSourceLog() {
+  static mozilla::LazyLogModule sLogModule("MediaSource");
+  return sLogModule;
+}
+
+mozilla::LogModule* GetMediaSourceAPILog() {
+  static mozilla::LazyLogModule sLogModule("MediaSource");
+  return sLogModule;
+}
+
+#define MSE_DEBUG(arg, ...)                                              \
+  DDMOZ_LOG(GetMediaSourceLog(), mozilla::LogLevel::Debug, "::%s: " arg, \
+            __func__, ##__VA_ARGS__)
+#define MSE_API(arg, ...)                                                   \
+  DDMOZ_LOG(GetMediaSourceAPILog(), mozilla::LogLevel::Debug, "::%s: " arg, \
+            __func__, ##__VA_ARGS__)
+
+// Arbitrary limit.
+static const unsigned int MAX_SOURCE_BUFFERS = 16;
+
+namespace mozilla {
+
+// Returns true if we should enable MSE webm regardless of preferences.
+// 1. If MP4/H264 isn't supported:
+//   * Windows XP
+//   * Windows Vista and Server 2008 without the optional "Platform Update
+//   Supplement"
+//   * N/KN editions (Europe and Korea) of Windows 7/8/8.1/10 without the
+//     optional "Windows Media Feature Pack"
+// 2. If H264 hardware acceleration is not available.
+// 3. The CPU is considered to be fast enough
+static bool IsVP9Forced(DecoderDoctorDiagnostics* aDiagnostics) {
+  bool mp4supported = DecoderTraits::IsMP4SupportedType(
+      MediaContainerType(MEDIAMIMETYPE(VIDEO_MP4)), aDiagnostics);
+  bool hwsupported = gfx::gfxVars::CanUseHardwareVideoDecoding();
+#ifdef MOZ_WIDGET_ANDROID
+  return !mp4supported || !hwsupported || VP9Benchmark::IsVP9DecodeFast() ||
+         java::HardwareCodecCapabilityUtils::HasHWVP9(false /* aIsEncoder */);
+#else
+  return !mp4supported || !hwsupported || VP9Benchmark::IsVP9DecodeFast();
+#endif
+}
+
+namespace dom {
+
+static void RecordTypeForTelemetry(const nsAString& aType,
+                                   nsPIDOMWindowInner* aWindow) {
+  Maybe<MediaContainerType> containerType = MakeMediaContainerType(aType);
+  if (!containerType) {
+    return;
+  }
+
+  const MediaMIMEType& mimeType = containerType->Type();
+  if (mimeType == MEDIAMIMETYPE(VIDEO_WEBM)) {
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_MSE_SOURCE_BUFFER_TYPE::VideoWebm);
+  } else if (mimeType == MEDIAMIMETYPE(AUDIO_WEBM)) {
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_MSE_SOURCE_BUFFER_TYPE::AudioWebm);
+  } else if (mimeType == MEDIAMIMETYPE(VIDEO_MP4)) {
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_MSE_SOURCE_BUFFER_TYPE::VideoMp4);
+  } else if (mimeType == MEDIAMIMETYPE(AUDIO_MP4)) {
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_MSE_SOURCE_BUFFER_TYPE::AudioMp4);
+  } else if (mimeType == MEDIAMIMETYPE(VIDEO_MPEG_TS)) {
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_MSE_SOURCE_BUFFER_TYPE::VideoMp2t);
+  } else if (mimeType == MEDIAMIMETYPE(AUDIO_MPEG_TS)) {
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_MSE_SOURCE_BUFFER_TYPE::AudioMp2t);
+  } else if (mimeType == MEDIAMIMETYPE(AUDIO_MP3)) {
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_MSE_SOURCE_BUFFER_TYPE::AudioMpeg);
+  } else if (mimeType == MEDIAMIMETYPE(AUDIO_AAC)) {
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_MSE_SOURCE_BUFFER_TYPE::AudioAac);
+  }
+}
+
+/* static */
+void MediaSource::IsTypeSupported(const nsAString& aType,
+                                  DecoderDoctorDiagnostics* aDiagnostics,
+                                  ErrorResult& aRv) {
+  if (aType.IsEmpty()) {
+    return aRv.ThrowTypeError("Empty type");
+  }
+
+  Maybe<MediaContainerType> containerType = MakeMediaContainerType(aType);
+  if (!containerType) {
+    return aRv.ThrowNotSupportedError("Unknown type");
+  }
+
+  if (DecoderTraits::CanHandleContainerType(*containerType, aDiagnostics) ==
+      CANPLAY_NO) {
+    return aRv.ThrowNotSupportedError("Can't play type");
+  }
+
+  bool hasVP9 = false;
+  const MediaCodecs& codecs = containerType->ExtendedType().Codecs();
+  for (const auto& codec : codecs.Range()) {
+    if (IsVP9CodecString(codec)) {
+      hasVP9 = true;
+      break;
+    }
+  }
+
+  // Now we know that this media type could be played.
+  // MediaSource imposes extra restrictions, and some prefs.
+  const MediaMIMEType& mimeType = containerType->Type();
+  if (mimeType == MEDIAMIMETYPE("video/mp4") ||
+      mimeType == MEDIAMIMETYPE("audio/mp4")) {
+    if (!StaticPrefs::media_mediasource_mp4_enabled()) {
+      // Don't leak information about the fact that it's pref-disabled; just act
+      // like we can't play it.  Or should this throw "Unknown type"?
+      return aRv.ThrowNotSupportedError("Can't play type");
+    }
+    if (!StaticPrefs::media_mediasource_vp9_enabled() && hasVP9 &&
+        !IsVP9Forced(aDiagnostics)) {
+      // Don't leak information about the fact that it's pref-disabled; just act
+      // like we can't play it.  Or should this throw "Unknown type"?
+      return aRv.ThrowNotSupportedError("Can't play type");
+    }
+
+    return;
+  }
+  if (mimeType == MEDIAMIMETYPE("video/webm")) {
+    if (!StaticPrefs::media_mediasource_webm_enabled()) {
+      // Don't leak information about the fact that it's pref-disabled; just act
+      // like we can't play it.  Or should this throw "Unknown type"?
+      return aRv.ThrowNotSupportedError("Can't play type");
+    }
+    if (!StaticPrefs::media_mediasource_vp9_enabled() && hasVP9 &&
+        !IsVP9Forced(aDiagnostics)) {
+      // Don't leak information about the fact that it's pref-disabled; just act
+      // like we can't play it.  Or should this throw "Unknown type"?
+      return aRv.ThrowNotSupportedError("Can't play type");
+    }
+    return;
+  }
+  if (mimeType == MEDIAMIMETYPE("audio/webm")) {
+    if (!(StaticPrefs::media_mediasource_webm_enabled() ||
+          StaticPrefs::media_mediasource_webm_audio_enabled())) {
+      // Don't leak information about the fact that it's pref-disabled; just act
+      // like we can't play it.  Or should this throw "Unknown type"?
+      return aRv.ThrowNotSupportedError("Can't play type");
+    }
+    return;
+  }
+
+  return aRv.ThrowNotSupportedError("Type not supported in MediaSource");
+}
+
+/* static */
+already_AddRefed<MediaSource> MediaSource::Constructor(
+    const GlobalObject& aGlobal, ErrorResult& aRv) {
+  nsCOMPtr<nsPIDOMWindowInner> window =
+      do_QueryInterface(aGlobal.GetAsSupports());
+  if (!window) {
+    aRv.Throw(NS_ERROR_UNEXPECTED);
+    return nullptr;
+  }
+
+  RefPtr<MediaSource> mediaSource = new MediaSource(window);
+  return mediaSource.forget();
+}
+
+MediaSource::~MediaSource() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_API("");
+  if (mDecoder) {
+    mDecoder->DetachMediaSource();
+  }
+}
+
+SourceBufferList* MediaSource::SourceBuffers() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT_IF(mReadyState == MediaSourceReadyState::Closed,
+                mSourceBuffers->IsEmpty());
+  return mSourceBuffers;
+}
+
+SourceBufferList* MediaSource::ActiveSourceBuffers() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT_IF(mReadyState == MediaSourceReadyState::Closed,
+                mActiveSourceBuffers->IsEmpty());
+  return mActiveSourceBuffers;
+}
+
+MediaSourceReadyState MediaSource::ReadyState() {
+  MOZ_ASSERT(NS_IsMainThread());
+  return mReadyState;
+}
+
+double MediaSource::Duration() {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (mReadyState == MediaSourceReadyState::Closed) {
+    return UnspecifiedNaN<double>();
+  }
+  MOZ_ASSERT(mDecoder);
+  return mDecoder->GetDuration();
+}
+
+void MediaSource::SetDuration(double aDuration, ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (aDuration < 0 || IsNaN(aDuration)) {
+    nsPrintfCString error("Invalid duration value %f", aDuration);
+    MSE_API("SetDuration(aDuration=%f, invalid value)", aDuration);
+    aRv.ThrowTypeError(error);
+    return;
+  }
+  if (mReadyState != MediaSourceReadyState::Open ||
+      mSourceBuffers->AnyUpdating()) {
+    MSE_API("SetDuration(aDuration=%f, invalid state)", aDuration);
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+  DurationChange(aDuration, aRv);
+  MSE_API("SetDuration(aDuration=%f, errorCode=%d)", aDuration,
+          aRv.ErrorCodeAsInt());
+}
+
+void MediaSource::SetDuration(double aDuration) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_API("SetDuration(aDuration=%f)", aDuration);
+  mDecoder->SetMediaSourceDuration(aDuration);
+}
+
+already_AddRefed<SourceBuffer> MediaSource::AddSourceBuffer(
+    const nsAString& aType, ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+  DecoderDoctorDiagnostics diagnostics;
+  IsTypeSupported(aType, &diagnostics, aRv);
+  RecordTypeForTelemetry(aType, GetOwner());
+  bool supported = !aRv.Failed();
+  diagnostics.StoreFormatDiagnostics(
+      GetOwner() ? GetOwner()->GetExtantDoc() : nullptr, aType, supported,
+      __func__);
+  MSE_API("AddSourceBuffer(aType=%s)%s", NS_ConvertUTF16toUTF8(aType).get(),
+          supported ? "" : " [not supported]");
+  if (!supported) {
+    return nullptr;
+  }
+  if (mSourceBuffers->Length() >= MAX_SOURCE_BUFFERS) {
+    aRv.Throw(NS_ERROR_DOM_QUOTA_EXCEEDED_ERR);
+    return nullptr;
+  }
+  if (mReadyState != MediaSourceReadyState::Open) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return nullptr;
+  }
+  Maybe<MediaContainerType> containerType = MakeMediaContainerType(aType);
+  if (!containerType) {
+    aRv.Throw(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
+    return nullptr;
+  }
+  RefPtr<SourceBuffer> sourceBuffer = new SourceBuffer(this, *containerType);
+  mSourceBuffers->Append(sourceBuffer);
+  DDLINKCHILD("sourcebuffer[]", sourceBuffer.get());
+  MSE_DEBUG("sourceBuffer=%p", sourceBuffer.get());
+  return sourceBuffer.forget();
+}
+
+RefPtr<MediaSource::ActiveCompletionPromise> MediaSource::SourceBufferIsActive(
+    SourceBuffer* aSourceBuffer) {
+  MOZ_ASSERT(NS_IsMainThread());
+  mActiveSourceBuffers->ClearSimple();
+  bool initMissing = false;
+  bool found = false;
+  for (uint32_t i = 0; i < mSourceBuffers->Length(); i++) {
+    SourceBuffer* sourceBuffer = mSourceBuffers->IndexedGetter(i, found);
+    MOZ_ALWAYS_TRUE(found);
+    if (sourceBuffer == aSourceBuffer) {
+      mActiveSourceBuffers->Append(aSourceBuffer);
+    } else if (sourceBuffer->IsActive()) {
+      mActiveSourceBuffers->AppendSimple(sourceBuffer);
+    } else {
+      // Some source buffers haven't yet received an init segment.
+      // There's nothing more we can do at this stage.
+      initMissing = true;
+    }
+  }
+  if (initMissing || !mDecoder) {
+    return ActiveCompletionPromise::CreateAndResolve(true, __func__);
+  }
+
+  mDecoder->NotifyInitDataArrived();
+
+  // Add our promise to the queue.
+  // It will be resolved once the HTMLMediaElement modifies its readyState.
+  MozPromiseHolder<ActiveCompletionPromise> holder;
+  RefPtr<ActiveCompletionPromise> promise = holder.Ensure(__func__);
+  mCompletionPromises.AppendElement(std::move(holder));
+  return promise;
+}
+
+void MediaSource::CompletePendingTransactions() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_DEBUG("Resolving %u promises", unsigned(mCompletionPromises.Length()));
+  for (auto& promise : mCompletionPromises) {
+    promise.Resolve(true, __func__);
+  }
+  mCompletionPromises.Clear();
+}
+
+void MediaSource::RemoveSourceBuffer(SourceBuffer& aSourceBuffer,
+                                     ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+  SourceBuffer* sourceBuffer = &aSourceBuffer;
+  MSE_API("RemoveSourceBuffer(aSourceBuffer=%p)", sourceBuffer);
+  if (!mSourceBuffers->Contains(sourceBuffer)) {
+    aRv.Throw(NS_ERROR_DOM_NOT_FOUND_ERR);
+    return;
+  }
+
+  sourceBuffer->AbortBufferAppend();
+  // TODO:
+  // abort stream append loop (if running)
+
+  // TODO:
+  // For all sourceBuffer audioTracks, videoTracks, textTracks:
+  //     set sourceBuffer to null
+  //     remove sourceBuffer video, audio, text Tracks from MediaElement tracks
+  //     remove sourceBuffer video, audio, text Tracks and fire "removetrack" at
+  //     affected lists fire "removetrack" at modified MediaElement track lists
+  // If removed enabled/selected, fire "change" at affected MediaElement list.
+  if (mActiveSourceBuffers->Contains(sourceBuffer)) {
+    mActiveSourceBuffers->Remove(sourceBuffer);
+  }
+  mSourceBuffers->Remove(sourceBuffer);
+  DDUNLINKCHILD(sourceBuffer);
+  // TODO: Free all resources associated with sourceBuffer
+}
+
+void MediaSource::EndOfStream(
+    const Optional<MediaSourceEndOfStreamError>& aError, ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_API("EndOfStream(aError=%d)",
+          aError.WasPassed() ? uint32_t(aError.Value()) : 0);
+  if (mReadyState != MediaSourceReadyState::Open ||
+      mSourceBuffers->AnyUpdating()) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+
+  SetReadyState(MediaSourceReadyState::Ended);
+  mSourceBuffers->Ended();
+  if (!aError.WasPassed()) {
+    DurationChange(mSourceBuffers->GetHighestBufferedEndTime(), aRv);
+    // Notify reader that all data is now available.
+    mDecoder->Ended(true);
+    return;
+  }
+  switch (aError.Value()) {
+    case MediaSourceEndOfStreamError::Network:
+      mDecoder->NetworkError(MediaResult(NS_ERROR_FAILURE, "MSE network"));
+      break;
+    case MediaSourceEndOfStreamError::Decode:
+      mDecoder->DecodeError(NS_ERROR_DOM_MEDIA_FATAL_ERR);
+      break;
+    default:
+      MOZ_ASSERT_UNREACHABLE(
+          "Someone added a MediaSourceReadyState value and didn't handle it "
+          "here");
+      break;
+  }
+}
+
+void MediaSource::EndOfStream(const MediaResult& aError) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_API("EndOfStream(aError=%s)", aError.ErrorName().get());
+
+  SetReadyState(MediaSourceReadyState::Ended);
+  mSourceBuffers->Ended();
+  mDecoder->DecodeError(aError);
+}
+
+/* static */
+bool MediaSource::IsTypeSupported(const GlobalObject& aOwner,
+                                  const nsAString& aType) {
+  MOZ_ASSERT(NS_IsMainThread());
+  DecoderDoctorDiagnostics diagnostics;
+  IgnoredErrorResult rv;
+  IsTypeSupported(aType, &diagnostics, rv);
+  bool supported = !rv.Failed();
+  nsCOMPtr<nsPIDOMWindowInner> window =
+      do_QueryInterface(aOwner.GetAsSupports());
+  RecordTypeForTelemetry(aType, window);
+  diagnostics.StoreFormatDiagnostics(window ? window->GetExtantDoc() : nullptr,
+                                     aType, supported, __func__);
+  MOZ_LOG(GetMediaSourceAPILog(), mozilla::LogLevel::Debug,
+          ("MediaSource::%s: IsTypeSupported(aType=%s) %s", __func__,
+           NS_ConvertUTF16toUTF8(aType).get(),
+           supported ? "OK" : "[not supported]"));
+  return supported;
+}
+
+void MediaSource::SetLiveSeekableRange(double aStart, double aEnd,
+                                       ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // 1. If the readyState attribute is not "open" then throw an
+  // InvalidStateError exception and abort these steps.
+  if (mReadyState != MediaSourceReadyState::Open) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+
+  // 2. If start is negative or greater than end, then throw a TypeError
+  // exception and abort these steps.
+  if (aStart < 0 || aStart > aEnd) {
+    aRv.ThrowTypeError("Invalid start value");
+    return;
+  }
+
+  // 3. Set live seekable range to be a new normalized TimeRanges object
+  // containing a single range whose start position is start and end position is
+  // end.
+  mLiveSeekableRange =
+      Some(media::TimeInterval(media::TimeUnit::FromSeconds(aStart),
+                               media::TimeUnit::FromSeconds(aEnd)));
+}
+
+void MediaSource::ClearLiveSeekableRange(ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // 1. If the readyState attribute is not "open" then throw an
+  // InvalidStateError exception and abort these steps.
+  if (mReadyState != MediaSourceReadyState::Open) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+
+  // 2. If live seekable range contains a range, then set live seekable range to
+  // be a new empty TimeRanges object.
+  mLiveSeekableRange.reset();
+}
+
+bool MediaSource::Attach(MediaSourceDecoder* aDecoder) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_DEBUG("Attach(aDecoder=%p) owner=%p", aDecoder, aDecoder->GetOwner());
+  MOZ_ASSERT(aDecoder);
+  MOZ_ASSERT(aDecoder->GetOwner());
+  if (mReadyState != MediaSourceReadyState::Closed) {
+    return false;
+  }
+  MOZ_ASSERT(!mMediaElement);
+  mMediaElement = aDecoder->GetOwner()->GetMediaElement();
+  MOZ_ASSERT(!mDecoder);
+  mDecoder = aDecoder;
+  mDecoder->AttachMediaSource(this);
+  SetReadyState(MediaSourceReadyState::Open);
+  return true;
+}
+
+void MediaSource::Detach() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_RELEASE_ASSERT(mCompletionPromises.IsEmpty());
+  MSE_DEBUG("mDecoder=%p owner=%p", mDecoder.get(),
+            mDecoder ? mDecoder->GetOwner() : nullptr);
+  if (!mDecoder) {
+    MOZ_ASSERT(mReadyState == MediaSourceReadyState::Closed);
+    MOZ_ASSERT(mActiveSourceBuffers->IsEmpty() && mSourceBuffers->IsEmpty());
+    return;
+  }
+  mMediaElement = nullptr;
+  SetReadyState(MediaSourceReadyState::Closed);
+  if (mActiveSourceBuffers) {
+    mActiveSourceBuffers->Clear();
+  }
+  if (mSourceBuffers) {
+    mSourceBuffers->Clear();
+  }
+  mDecoder->DetachMediaSource();
+  mDecoder = nullptr;
+}
+
+MediaSource::MediaSource(nsPIDOMWindowInner* aWindow)
+    : DOMEventTargetHelper(aWindow),
+      mDecoder(nullptr),
+      mPrincipal(nullptr),
+      mAbstractMainThread(
+          GetOwnerGlobal()->AbstractMainThreadFor(TaskCategory::Other)),
+      mReadyState(MediaSourceReadyState::Closed) {
+  MOZ_ASSERT(NS_IsMainThread());
+  mSourceBuffers = new SourceBufferList(this);
+  mActiveSourceBuffers = new SourceBufferList(this);
+
+  nsCOMPtr<nsIScriptObjectPrincipal> sop = do_QueryInterface(aWindow);
+  if (sop) {
+    mPrincipal = sop->GetPrincipal();
+  }
+
+  MSE_API("MediaSource(aWindow=%p) mSourceBuffers=%p mActiveSourceBuffers=%p",
+          aWindow, mSourceBuffers.get(), mActiveSourceBuffers.get());
+}
+
+void MediaSource::SetReadyState(MediaSourceReadyState aState) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aState != mReadyState);
+  MSE_DEBUG("SetReadyState(aState=%" PRIu32 ") mReadyState=%" PRIu32,
+            static_cast<uint32_t>(aState), static_cast<uint32_t>(mReadyState));
+
+  MediaSourceReadyState oldState = mReadyState;
+  mReadyState = aState;
+
+  if (mReadyState == MediaSourceReadyState::Open &&
+      (oldState == MediaSourceReadyState::Closed ||
+       oldState == MediaSourceReadyState::Ended)) {
+    QueueAsyncSimpleEvent("sourceopen");
+    if (oldState == MediaSourceReadyState::Ended) {
+      // Notify reader that more data may come.
+      mDecoder->Ended(false);
+    }
+    return;
+  }
+
+  if (mReadyState == MediaSourceReadyState::Ended &&
+      oldState == MediaSourceReadyState::Open) {
+    QueueAsyncSimpleEvent("sourceended");
+    return;
+  }
+
+  if (mReadyState == MediaSourceReadyState::Closed &&
+      (oldState == MediaSourceReadyState::Open ||
+       oldState == MediaSourceReadyState::Ended)) {
+    QueueAsyncSimpleEvent("sourceclose");
+    return;
+  }
+
+  NS_WARNING("Invalid MediaSource readyState transition");
+}
+
+void MediaSource::DispatchSimpleEvent(const char* aName) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_API("Dispatch event '%s'", aName);
+  DispatchTrustedEvent(NS_ConvertUTF8toUTF16(aName));
+}
+
+void MediaSource::QueueAsyncSimpleEvent(const char* aName) {
+  MSE_DEBUG("Queuing event '%s'", aName);
+  nsCOMPtr<nsIRunnable> event = new AsyncEventRunner<MediaSource>(this, aName);
+  mAbstractMainThread->Dispatch(event.forget());
+}
+
+void MediaSource::DurationChange(double aNewDuration, ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_DEBUG("DurationChange(aNewDuration=%f)", aNewDuration);
+
+  // 1. If the current value of duration is equal to new duration, then return.
+  if (mDecoder->GetDuration() == aNewDuration) {
+    return;
+  }
+
+  // 2. If new duration is less than the highest starting presentation timestamp
+  // of any buffered coded frames for all SourceBuffer objects in sourceBuffers,
+  // then throw an InvalidStateError exception and abort these steps.
+  if (aNewDuration < mSourceBuffers->HighestStartTime()) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+
+  // 3. Let highest end time be the largest track buffer ranges end time across
+  // all the track buffers across all SourceBuffer objects in sourceBuffers.
+  double highestEndTime = mSourceBuffers->HighestEndTime();
+  // 4. If new duration is less than highest end time, then
+  //    4.1 Update new duration to equal highest end time.
+  aNewDuration = std::max(aNewDuration, highestEndTime);
+
+  // 5. Update the media duration to new duration and run the HTMLMediaElement
+  // duration change algorithm.
+  mDecoder->SetMediaSourceDuration(aNewDuration);
+}
+
+already_AddRefed<Promise> MediaSource::MozDebugReaderData(ErrorResult& aRv) {
+  // Creating a JS promise
+  nsPIDOMWindowInner* win = GetOwner();
+  if (!win) {
+    aRv.Throw(NS_ERROR_UNEXPECTED);
+    return nullptr;
+  }
+  RefPtr<Promise> domPromise = Promise::Create(win->AsGlobal(), aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+  MOZ_ASSERT(domPromise);
+  UniquePtr<MediaSourceDecoderDebugInfo> info =
+      MakeUnique<MediaSourceDecoderDebugInfo>();
+  mDecoder->RequestDebugInfo(*info)->Then(
+      mAbstractMainThread, __func__,
+      [domPromise, infoPtr = std::move(info)] {
+        domPromise->MaybeResolve(infoPtr.get());
+      },
+      [] {
+        MOZ_ASSERT_UNREACHABLE("Unexpected rejection while getting debug data");
+      });
+
+  return domPromise.forget();
+}
+
+nsPIDOMWindowInner* MediaSource::GetParentObject() const { return GetOwner(); }
+
+JSObject* MediaSource::WrapObject(JSContext* aCx,
+                                  JS::Handle<JSObject*> aGivenProto) {
+  return MediaSource_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+NS_IMPL_CYCLE_COLLECTION_INHERITED(MediaSource, DOMEventTargetHelper,
+                                   mMediaElement, mSourceBuffers,
+                                   mActiveSourceBuffers)
+
+NS_IMPL_ADDREF_INHERITED(MediaSource, DOMEventTargetHelper)
+NS_IMPL_RELEASE_INHERITED(MediaSource, DOMEventTargetHelper)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(MediaSource)
+  NS_INTERFACE_MAP_ENTRY(mozilla::dom::MediaSource)
+NS_INTERFACE_MAP_END_INHERITING(DOMEventTargetHelper)
+
+#undef MSE_DEBUG
+#undef MSE_API
+
+}  // namespace dom
+
+}  // namespace mozilla
diff --git a/dom/media/mediasource/MediaSource.h b/dom/media/mediasource/MediaSource.h
new file mode 100644
index 0000000000..51936d9a5a
--- /dev/null
+++ b/dom/media/mediasource/MediaSource.h
@@ -0,0 +1,181 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_MediaSource_h_
+#define mozilla_dom_MediaSource_h_
+
+#include "MediaSourceDecoder.h"
+#include "js/RootingAPI.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/DOMEventTargetHelper.h"
+#include "mozilla/MozPromise.h"
+#include "mozilla/dom/MediaSourceBinding.h"
+#include "nsCOMPtr.h"
+#include "nsCycleCollectionNoteChild.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsID.h"
+#include "nsISupports.h"
+#include "nscore.h"
+#include "TimeUnits.h"
+
+struct JSContext;
+class JSObject;
+class nsPIDOMWindowInner;
+
+namespace mozilla {
+
+class AbstractThread;
+class ErrorResult;
+template <typename T>
+class AsyncEventRunner;
+class MediaResult;
+
+namespace dom {
+class MediaSource;
+}  // namespace dom
+DDLoggedTypeName(dom::MediaSource);
+
+namespace dom {
+
+class GlobalObject;
+class SourceBuffer;
+class SourceBufferList;
+template <typename T>
+class Optional;
+
+#define MOZILLA_DOM_MEDIASOURCE_IMPLEMENTATION_IID   \
+  {                                                  \
+    0x3839d699, 0x22c5, 0x439f, {                    \
+      0x94, 0xca, 0x0e, 0x0b, 0x26, 0xf9, 0xca, 0xbf \
+    }                                                \
+  }
+
+class MediaSource final : public DOMEventTargetHelper,
+                          public DecoderDoctorLifeLogger<MediaSource> {
+ public:
+  /** WebIDL Methods. */
+  static already_AddRefed<MediaSource> Constructor(const GlobalObject& aGlobal,
+                                                   ErrorResult& aRv);
+
+  SourceBufferList* SourceBuffers();
+  SourceBufferList* ActiveSourceBuffers();
+  MediaSourceReadyState ReadyState();
+
+  double Duration();
+  void SetDuration(double aDuration, ErrorResult& aRv);
+
+  already_AddRefed<SourceBuffer> AddSourceBuffer(const nsAString& aType,
+                                                 ErrorResult& aRv);
+  void RemoveSourceBuffer(SourceBuffer& aSourceBuffer, ErrorResult& aRv);
+
+  void EndOfStream(const Optional<MediaSourceEndOfStreamError>& aError,
+                   ErrorResult& aRv);
+  void EndOfStream(const MediaResult& aError);
+
+  void SetLiveSeekableRange(double aStart, double aEnd, ErrorResult& aRv);
+  void ClearLiveSeekableRange(ErrorResult& aRv);
+
+  static bool IsTypeSupported(const GlobalObject&, const nsAString& aType);
+  // Throws on aRv if not supported.
+  static void IsTypeSupported(const nsAString& aType,
+                              DecoderDoctorDiagnostics* aDiagnostics,
+                              ErrorResult& aRv);
+
+  IMPL_EVENT_HANDLER(sourceopen);
+  IMPL_EVENT_HANDLER(sourceended);
+  IMPL_EVENT_HANDLER(sourceclose);
+
+  /** End WebIDL Methods. */
+
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(MediaSource, DOMEventTargetHelper)
+  NS_DECLARE_STATIC_IID_ACCESSOR(MOZILLA_DOM_MEDIASOURCE_IMPLEMENTATION_IID)
+
+  nsPIDOMWindowInner* GetParentObject() const;
+
+  JSObject* WrapObject(JSContext* aCx,
+                       JS::Handle<JSObject*> aGivenProto) override;
+
+  // Attach this MediaSource to Decoder aDecoder.  Returns false if already
+  // attached.
+  bool Attach(MediaSourceDecoder* aDecoder);
+  void Detach();
+
+  // Set mReadyState to aState and fire the required events at the MediaSource.
+  void SetReadyState(MediaSourceReadyState aState);
+
+  // Used by SourceBuffer to call CreateSubDecoder.
+  MediaSourceDecoder* GetDecoder() { return mDecoder; }
+
+  nsIPrincipal* GetPrincipal() { return mPrincipal; }
+
+  // Returns a structure describing the state of the MediaSource internal
+  // buffered data. Used for debugging purposes.
+  already_AddRefed<Promise> MozDebugReaderData(ErrorResult& aRv);
+
+  bool HasLiveSeekableRange() const { return mLiveSeekableRange.isSome(); }
+  media::TimeInterval LiveSeekableRange() const {
+    return mLiveSeekableRange.value();
+  }
+
+  AbstractThread* AbstractMainThread() const { return mAbstractMainThread; }
+
+  // Resolve all CompletionPromise pending.
+  void CompletePendingTransactions();
+
+ private:
+  // SourceBuffer uses SetDuration and SourceBufferIsActive
+  friend class mozilla::dom::SourceBuffer;
+
+  ~MediaSource();
+
+  explicit MediaSource(nsPIDOMWindowInner* aWindow);
+
+  friend class AsyncEventRunner<MediaSource>;
+  void DispatchSimpleEvent(const char* aName);
+  void QueueAsyncSimpleEvent(const char* aName);
+
+  void DurationChange(double aNewDuration, ErrorResult& aRv);
+
+  // SetDuration with no checks.
+  void SetDuration(double aDuration);
+
+  typedef MozPromise<bool, MediaResult, /* IsExclusive = */ true>
+      ActiveCompletionPromise;
+  // Mark SourceBuffer as active and rebuild ActiveSourceBuffers.
+  // Return a MozPromise that will be resolved once all related operations are
+  // completed, or can't progress any further.
+  // Such as, transition of readyState from HAVE_NOTHING to HAVE_METADATA.
+  RefPtr<ActiveCompletionPromise> SourceBufferIsActive(
+      SourceBuffer* aSourceBuffer);
+
+  RefPtr<SourceBufferList> mSourceBuffers;
+  RefPtr<SourceBufferList> mActiveSourceBuffers;
+
+  RefPtr<MediaSourceDecoder> mDecoder;
+  // Ensures the media element remains alive to dispatch progress and
+  // durationchanged events.
+  RefPtr<HTMLMediaElement> mMediaElement;
+
+  RefPtr<nsIPrincipal> mPrincipal;
+
+  const RefPtr<AbstractThread> mAbstractMainThread;
+
+  MediaSourceReadyState mReadyState;
+
+  Maybe<media::TimeInterval> mLiveSeekableRange;
+  nsTArray<MozPromiseHolder<ActiveCompletionPromise>> mCompletionPromises;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(MediaSource,
+                              MOZILLA_DOM_MEDIASOURCE_IMPLEMENTATION_IID)
+
+}  // namespace dom
+
+}  // namespace mozilla
+
+#endif /* mozilla_dom_MediaSource_h_ */
diff --git a/dom/media/mediasource/MediaSourceDecoder.cpp b/dom/media/mediasource/MediaSourceDecoder.cpp
new file mode 100644
index 0000000000..e40d15267c
--- /dev/null
+++ b/dom/media/mediasource/MediaSourceDecoder.cpp
@@ -0,0 +1,353 @@
+/* -*- mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include "MediaSourceDecoder.h"
+
+#include "base/process_util.h"
+#include "mozilla/Logging.h"
+#include "ExternalEngineStateMachine.h"
+#include "MediaDecoderStateMachine.h"
+#include "MediaShutdownManager.h"
+#include "MediaSource.h"
+#include "MediaSourceDemuxer.h"
+#include "MediaSourceUtils.h"
+#include "SourceBuffer.h"
+#include "SourceBufferList.h"
+#include "VideoUtils.h"
+#include <algorithm>
+
+extern mozilla::LogModule* GetMediaSourceLog();
+
+#define MSE_DEBUG(arg, ...)                                              \
+  DDMOZ_LOG(GetMediaSourceLog(), mozilla::LogLevel::Debug, "::%s: " arg, \
+            __func__, ##__VA_ARGS__)
+#define MSE_DEBUGV(arg, ...)                                               \
+  DDMOZ_LOG(GetMediaSourceLog(), mozilla::LogLevel::Verbose, "::%s: " arg, \
+            __func__, ##__VA_ARGS__)
+
+using namespace mozilla::media;
+
+namespace mozilla {
+
+MediaSourceDecoder::MediaSourceDecoder(MediaDecoderInit& aInit)
+    : MediaDecoder(aInit), mMediaSource(nullptr), mEnded(false) {
+  mExplicitDuration.emplace(UnspecifiedNaN<double>());
+}
+
+MediaDecoderStateMachineBase* MediaSourceDecoder::CreateStateMachine(
+    bool aDisableExternalEngine) {
+  MOZ_ASSERT(NS_IsMainThread());
+  // if `mDemuxer` already exists, that means we're in the process of recreating
+  // the state machine. The track buffers are tied to the demuxer so we would
+  // need to reuse it.
+  if (!mDemuxer) {
+    mDemuxer = new MediaSourceDemuxer(AbstractMainThread());
+  }
+  MediaFormatReaderInit init;
+  init.mVideoFrameContainer = GetVideoFrameContainer();
+  init.mKnowsCompositor = GetCompositor();
+  init.mCrashHelper = GetOwner()->CreateGMPCrashHelper();
+  init.mFrameStats = mFrameStats;
+  init.mMediaDecoderOwnerID = mOwner;
+  static Atomic<uint32_t> sTrackingIdCounter(0);
+  init.mTrackingId.emplace(TrackingId::Source::MSEDecoder, sTrackingIdCounter++,
+                           TrackingId::TrackAcrossProcesses::Yes);
+  mReader = new MediaFormatReader(init, mDemuxer);
+#ifdef MOZ_WMF_MEDIA_ENGINE
+  // TODO : Only for testing development for now. In the future this should be
+  // used for encrypted content only.
+  if (StaticPrefs::media_wmf_media_engine_enabled() &&
+      !aDisableExternalEngine) {
+    return new ExternalEngineStateMachine(this, mReader);
+  }
+#endif
+  return new MediaDecoderStateMachine(this, mReader);
+}
+
+nsresult MediaSourceDecoder::Load(nsIPrincipal* aPrincipal) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!GetStateMachine());
+
+  mPrincipal = aPrincipal;
+
+  nsresult rv = MediaShutdownManager::Instance().Register(this);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+  return CreateAndInitStateMachine(!mEnded);
+}
+
+media::TimeIntervals MediaSourceDecoder::GetSeekable() {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (!mMediaSource) {
+    NS_WARNING("MediaSource element isn't attached");
+    return media::TimeIntervals::Invalid();
+  }
+
+  media::TimeIntervals seekable;
+  double duration = mMediaSource->Duration();
+  if (IsNaN(duration)) {
+    // Return empty range.
+  } else if (duration > 0 && mozilla::IsInfinite(duration)) {
+    media::TimeIntervals buffered = GetBuffered();
+
+    // 1. If live seekable range is not empty:
+    if (mMediaSource->HasLiveSeekableRange()) {
+      // 1. Let union ranges be the union of live seekable range and the
+      // HTMLMediaElement.buffered attribute.
+      media::TimeIntervals unionRanges =
+          buffered + mMediaSource->LiveSeekableRange();
+      // 2. Return a single range with a start time equal to the earliest start
+      // time in union ranges and an end time equal to the highest end time in
+      // union ranges and abort these steps.
+      seekable +=
+          media::TimeInterval(unionRanges.GetStart(), unionRanges.GetEnd());
+      return seekable;
+    }
+
+    if (!buffered.IsEmpty()) {
+      seekable += media::TimeInterval(TimeUnit::Zero(), buffered.GetEnd());
+    }
+  } else {
+    seekable +=
+        media::TimeInterval(TimeUnit::Zero(), TimeUnit::FromSeconds(duration));
+  }
+  MSE_DEBUG("ranges=%s", DumpTimeRanges(seekable).get());
+  return seekable;
+}
+
+media::TimeIntervals MediaSourceDecoder::GetBuffered() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!mMediaSource) {
+    NS_WARNING("MediaSource element isn't attached");
+    return media::TimeIntervals::Invalid();
+  }
+  dom::SourceBufferList* sourceBuffers = mMediaSource->ActiveSourceBuffers();
+  if (!sourceBuffers) {
+    // Media source object is shutting down.
+    return TimeIntervals();
+  }
+  TimeUnit highestEndTime;
+  nsTArray<media::TimeIntervals> activeRanges;
+  media::TimeIntervals buffered;
+
+  for (uint32_t i = 0; i < sourceBuffers->Length(); i++) {
+    bool found;
+    dom::SourceBuffer* sb = sourceBuffers->IndexedGetter(i, found);
+    MOZ_ASSERT(found);
+
+    activeRanges.AppendElement(sb->GetTimeIntervals());
+    highestEndTime =
+        std::max(highestEndTime, activeRanges.LastElement().GetEnd());
+  }
+
+  buffered += media::TimeInterval(TimeUnit::Zero(), highestEndTime);
+
+  for (auto& range : activeRanges) {
+    if (mEnded && !range.IsEmpty()) {
+      // Set the end time on the last range to highestEndTime by adding a
+      // new range spanning the current end time to highestEndTime, which
+      // Normalize() will then merge with the old last range.
+      range += media::TimeInterval(range.GetEnd(), highestEndTime);
+    }
+    buffered.Intersection(range);
+  }
+
+  MSE_DEBUG("ranges=%s", DumpTimeRanges(buffered).get());
+  return buffered;
+}
+
+void MediaSourceDecoder::Shutdown() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_DEBUG("Shutdown");
+  // Detach first so that TrackBuffers are unused on the main thread when
+  // shut down on the decode task queue.
+  if (mMediaSource) {
+    mMediaSource->Detach();
+  }
+  mDemuxer = nullptr;
+
+  MediaDecoder::Shutdown();
+}
+
+void MediaSourceDecoder::AttachMediaSource(dom::MediaSource* aMediaSource) {
+  MOZ_ASSERT(!mMediaSource && !GetStateMachine() && NS_IsMainThread());
+  mMediaSource = aMediaSource;
+  DDLINKCHILD("mediasource", aMediaSource);
+}
+
+void MediaSourceDecoder::DetachMediaSource() {
+  MOZ_ASSERT(mMediaSource && NS_IsMainThread());
+  DDUNLINKCHILD(mMediaSource);
+  mMediaSource = nullptr;
+}
+
+void MediaSourceDecoder::Ended(bool aEnded) {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (aEnded) {
+    // We want the MediaSourceReader to refresh its buffered range as it may
+    // have been modified (end lined up).
+    NotifyDataArrived();
+  }
+  mEnded = aEnded;
+  GetStateMachine()->DispatchIsLiveStream(!mEnded);
+}
+
+void MediaSourceDecoder::AddSizeOfResources(ResourceSizes* aSizes) {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (GetDemuxer()) {
+    GetDemuxer()->AddSizeOfResources(aSizes);
+  }
+}
+
+void MediaSourceDecoder::SetInitialDuration(int64_t aDuration) {
+  MOZ_ASSERT(NS_IsMainThread());
+  // Only use the decoded duration if one wasn't already
+  // set.
+  if (!mMediaSource || !IsNaN(ExplicitDuration())) {
+    return;
+  }
+  double duration = aDuration;
+  // A duration of -1 is +Infinity.
+  if (aDuration >= 0) {
+    duration /= USECS_PER_S;
+  }
+  SetMediaSourceDuration(duration);
+}
+
+void MediaSourceDecoder::SetMediaSourceDuration(double aDuration) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!IsShutdown());
+  if (aDuration >= 0) {
+    int64_t checkedDuration;
+    if (NS_FAILED(SecondsToUsecs(aDuration, checkedDuration))) {
+      // INT64_MAX is used as infinity by the state machine.
+      // We want a very bigger number, but not infinity.
+      checkedDuration = INT64_MAX - 1;
+    }
+    SetExplicitDuration(aDuration);
+  } else {
+    SetExplicitDuration(PositiveInfinity<double>());
+  }
+}
+
+RefPtr<GenericPromise> MediaSourceDecoder::RequestDebugInfo(
+    dom::MediaSourceDecoderDebugInfo& aInfo) {
+  // This should be safe to call off main thead, but there's no such usage at
+  // time of writing. Can be carefully relaxed if needed.
+  MOZ_ASSERT(NS_IsMainThread(), "Expects to be called on main thread.");
+  nsTArray<RefPtr<GenericPromise>> promises;
+  if (mReader) {
+    promises.AppendElement(mReader->RequestDebugInfo(aInfo.mReader));
+  }
+  if (mDemuxer) {
+    promises.AppendElement(mDemuxer->GetDebugInfo(aInfo.mDemuxer));
+  }
+  return GenericPromise::All(GetCurrentSerialEventTarget(), promises)
+      ->Then(
+          GetCurrentSerialEventTarget(), __func__,
+          []() { return GenericPromise::CreateAndResolve(true, __func__); },
+          [] {
+            return GenericPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
+          });
+}
+
+double MediaSourceDecoder::GetDuration() {
+  MOZ_ASSERT(NS_IsMainThread());
+  return ExplicitDuration();
+}
+
+MediaDecoderOwner::NextFrameStatus
+MediaSourceDecoder::NextFrameBufferedStatus() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!mMediaSource ||
+      mMediaSource->ReadyState() == dom::MediaSourceReadyState::Closed) {
+    return MediaDecoderOwner::NEXT_FRAME_UNAVAILABLE;
+  }
+
+  // Next frame hasn't been decoded yet.
+  // Use the buffered range to consider if we have the next frame available.
+  auto currentPosition = CurrentPosition();
+  TimeIntervals buffered = GetBuffered();
+  buffered.SetFuzz(MediaSourceDemuxer::EOS_FUZZ / 2);
+  TimeInterval interval(
+      currentPosition, currentPosition + DEFAULT_NEXT_FRAME_AVAILABLE_BUFFERED);
+  return buffered.ContainsWithStrictEnd(ClampIntervalToEnd(interval))
+             ? MediaDecoderOwner::NEXT_FRAME_AVAILABLE
+             : MediaDecoderOwner::NEXT_FRAME_UNAVAILABLE;
+}
+
+bool MediaSourceDecoder::CanPlayThroughImpl() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (NextFrameBufferedStatus() == MediaDecoderOwner::NEXT_FRAME_UNAVAILABLE) {
+    return false;
+  }
+
+  if (IsNaN(mMediaSource->Duration())) {
+    // Don't have any data yet.
+    return false;
+  }
+  TimeUnit duration = TimeUnit::FromSeconds(mMediaSource->Duration());
+  auto currentPosition = CurrentPosition();
+  if (duration <= currentPosition) {
+    return true;
+  }
+  // If we have data up to the mediasource's duration or 3s ahead, we can
+  // assume that we can play without interruption.
+  TimeIntervals buffered = GetBuffered();
+  buffered.SetFuzz(MediaSourceDemuxer::EOS_FUZZ / 2);
+  TimeUnit timeAhead =
+      std::min(duration, currentPosition + TimeUnit::FromSeconds(3));
+  TimeInterval interval(currentPosition, timeAhead);
+  return buffered.ContainsWithStrictEnd(ClampIntervalToEnd(interval));
+}
+
+TimeInterval MediaSourceDecoder::ClampIntervalToEnd(
+    const TimeInterval& aInterval) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!mEnded) {
+    return aInterval;
+  }
+  TimeUnit duration = TimeUnit::FromSeconds(GetDuration());
+  if (duration < aInterval.mStart) {
+    return aInterval;
+  }
+  return TimeInterval(aInterval.mStart, std::min(aInterval.mEnd, duration),
+                      aInterval.mFuzz);
+}
+
+void MediaSourceDecoder::NotifyInitDataArrived() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (mDemuxer) {
+    mDemuxer->NotifyInitDataArrived();
+  }
+}
+
+void MediaSourceDecoder::NotifyDataArrived() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_DIAGNOSTIC_ASSERT(!IsShutdown());
+  NotifyReaderDataArrived();
+  GetOwner()->DownloadProgressed();
+}
+
+already_AddRefed<nsIPrincipal> MediaSourceDecoder::GetCurrentPrincipal() {
+  MOZ_ASSERT(NS_IsMainThread());
+  return do_AddRef(mPrincipal);
+}
+
+bool MediaSourceDecoder::HadCrossOriginRedirects() {
+  MOZ_ASSERT(NS_IsMainThread());
+  return false;
+}
+
+#undef MSE_DEBUG
+#undef MSE_DEBUGV
+
+}  // namespace mozilla
diff --git a/dom/media/mediasource/MediaSourceDecoder.h b/dom/media/mediasource/MediaSourceDecoder.h
new file mode 100644
index 0000000000..3c7b076556
--- /dev/null
+++ b/dom/media/mediasource/MediaSourceDecoder.h
@@ -0,0 +1,95 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_MEDIASOURCEDECODER_H_
+#define MOZILLA_MEDIASOURCEDECODER_H_
+
+#include "MediaDecoder.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/dom/MediaDebugInfoBinding.h"
+
+namespace mozilla {
+
+class MediaDecoderStateMachineBase;
+class MediaSourceDemuxer;
+
+namespace dom {
+
+class MediaSource;
+
+}  // namespace dom
+
+DDLoggedTypeDeclNameAndBase(MediaSourceDecoder, MediaDecoder);
+
+class MediaSourceDecoder : public MediaDecoder,
+                           public DecoderDoctorLifeLogger<MediaSourceDecoder> {
+ public:
+  explicit MediaSourceDecoder(MediaDecoderInit& aInit);
+
+  nsresult Load(nsIPrincipal* aPrincipal);
+  media::TimeIntervals GetSeekable() override;
+  media::TimeIntervals GetBuffered() override;
+
+  void Shutdown() override;
+
+  void AttachMediaSource(dom::MediaSource* aMediaSource);
+  void DetachMediaSource();
+
+  void Ended(bool aEnded);
+
+  // Return the duration of the video in seconds.
+  double GetDuration() override;
+
+  void SetInitialDuration(int64_t aDuration);
+  void SetMediaSourceDuration(double aDuration);
+
+  MediaSourceDemuxer* GetDemuxer() { return mDemuxer; }
+
+  already_AddRefed<nsIPrincipal> GetCurrentPrincipal() override;
+
+  bool HadCrossOriginRedirects() override;
+
+  bool IsTransportSeekable() override { return true; }
+
+  // Requests that the MediaSourceDecoder populates aInfo with debug
+  // information. This may be done asynchronously, and aInfo should *not* be
+  // accessed by the caller until the returned promise is resolved or rejected.
+  RefPtr<GenericPromise> RequestDebugInfo(
+      dom::MediaSourceDecoderDebugInfo& aInfo);
+
+  void AddSizeOfResources(ResourceSizes* aSizes) override;
+
+  MediaDecoderOwner::NextFrameStatus NextFrameBufferedStatus() override;
+
+  bool IsMSE() const override { return true; }
+
+  void NotifyInitDataArrived();
+
+  // Called as data appended to the source buffer or EOS is called on the media
+  // source. Main thread only.
+  void NotifyDataArrived();
+
+ private:
+  MediaDecoderStateMachineBase* CreateStateMachine(
+      bool aDisableExternalEngine) override;
+  void DoSetMediaSourceDuration(double aDuration);
+  media::TimeInterval ClampIntervalToEnd(const media::TimeInterval& aInterval);
+  bool CanPlayThroughImpl() override;
+
+  RefPtr<nsIPrincipal> mPrincipal;
+
+  // The owning MediaSource holds a strong reference to this decoder, and
+  // calls Attach/DetachMediaSource on this decoder to set and clear
+  // mMediaSource.
+  dom::MediaSource* mMediaSource;
+  RefPtr<MediaSourceDemuxer> mDemuxer;
+
+  bool mEnded;
+};
+
+}  // namespace mozilla
+
+#endif /* MOZILLA_MEDIASOURCEDECODER_H_ */
diff --git a/dom/media/mediasource/MediaSourceDemuxer.cpp b/dom/media/mediasource/MediaSourceDemuxer.cpp
new file mode 100644
index 0000000000..945218da13
--- /dev/null
+++ b/dom/media/mediasource/MediaSourceDemuxer.cpp
@@ -0,0 +1,519 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "MediaSourceDemuxer.h"
+
+#include "MediaSourceUtils.h"
+#include "OpusDecoder.h"
+#include "SourceBufferList.h"
+#include "VorbisDecoder.h"
+#include "VideoUtils.h"
+#include "nsPrintfCString.h"
+
+#include <algorithm>
+#include <limits>
+#include <stdint.h>
+
+namespace mozilla {
+
+typedef TrackInfo::TrackType TrackType;
+using media::TimeIntervals;
+using media::TimeUnit;
+
+MediaSourceDemuxer::MediaSourceDemuxer(AbstractThread* aAbstractMainThread)
+    : mTaskQueue(
+          TaskQueue::Create(GetMediaThreadPool(MediaThreadType::SUPERVISOR),
+                            "MediaSourceDemuxer::mTaskQueue")),
+      mMonitor("MediaSourceDemuxer") {
+  MOZ_ASSERT(NS_IsMainThread());
+}
+
+constexpr TimeUnit MediaSourceDemuxer::EOS_FUZZ;
+constexpr TimeUnit MediaSourceDemuxer::EOS_FUZZ_START;
+
+RefPtr<MediaSourceDemuxer::InitPromise> MediaSourceDemuxer::Init() {
+  RefPtr<MediaSourceDemuxer> self = this;
+  return InvokeAsync(GetTaskQueue(), __func__, [self]() {
+    if (self->ScanSourceBuffersForContent()) {
+      return InitPromise::CreateAndResolve(NS_OK, __func__);
+    }
+
+    RefPtr<InitPromise> p = self->mInitPromise.Ensure(__func__);
+
+    return p;
+  });
+}
+
+void MediaSourceDemuxer::AddSizeOfResources(
+    MediaSourceDecoder::ResourceSizes* aSizes) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // NB: The track buffers must only be accessed on the TaskQueue.
+  RefPtr<MediaSourceDemuxer> self = this;
+  RefPtr<MediaSourceDecoder::ResourceSizes> sizes = aSizes;
+  nsCOMPtr<nsIRunnable> task = NS_NewRunnableFunction(
+      "MediaSourceDemuxer::AddSizeOfResources", [self, sizes]() {
+        for (const RefPtr<TrackBuffersManager>& manager :
+             self->mSourceBuffers) {
+          manager->AddSizeOfResources(sizes);
+        }
+      });
+
+  nsresult rv = GetTaskQueue()->Dispatch(task.forget());
+  MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(rv));
+  Unused << rv;
+}
+
+void MediaSourceDemuxer::NotifyInitDataArrived() {
+  RefPtr<MediaSourceDemuxer> self = this;
+  nsCOMPtr<nsIRunnable> task = NS_NewRunnableFunction(
+      "MediaSourceDemuxer::NotifyInitDataArrived", [self]() {
+        if (self->mInitPromise.IsEmpty()) {
+          return;
+        }
+        if (self->ScanSourceBuffersForContent()) {
+          self->mInitPromise.ResolveIfExists(NS_OK, __func__);
+        }
+      });
+  nsresult rv = GetTaskQueue()->Dispatch(task.forget());
+  MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(rv));
+  Unused << rv;
+}
+
+bool MediaSourceDemuxer::ScanSourceBuffersForContent() {
+  MOZ_ASSERT(OnTaskQueue());
+
+  if (mSourceBuffers.IsEmpty()) {
+    return false;
+  }
+
+  MonitorAutoLock mon(mMonitor);
+
+  bool haveEmptySourceBuffer = false;
+  for (const auto& sourceBuffer : mSourceBuffers) {
+    MediaInfo info = sourceBuffer->GetMetadata();
+    if (!info.HasAudio() && !info.HasVideo()) {
+      haveEmptySourceBuffer = true;
+    }
+    if (info.HasAudio() && !mAudioTrack) {
+      mInfo.mAudio = info.mAudio;
+      mAudioTrack = sourceBuffer;
+    }
+    if (info.HasVideo() && !mVideoTrack) {
+      mInfo.mVideo = info.mVideo;
+      mVideoTrack = sourceBuffer;
+    }
+    if (info.IsEncrypted() && !mInfo.IsEncrypted()) {
+      mInfo.mCrypto = info.mCrypto;
+    }
+  }
+  if (mInfo.HasAudio() && mInfo.HasVideo()) {
+    // We have both audio and video. We can ignore non-ready source buffer.
+    return true;
+  }
+  return !haveEmptySourceBuffer;
+}
+
+uint32_t MediaSourceDemuxer::GetNumberTracks(TrackType aType) const {
+  MonitorAutoLock mon(mMonitor);
+
+  switch (aType) {
+    case TrackType::kAudioTrack:
+      return mInfo.HasAudio() ? 1u : 0;
+    case TrackType::kVideoTrack:
+      return mInfo.HasVideo() ? 1u : 0;
+    default:
+      return 0;
+  }
+}
+
+already_AddRefed<MediaTrackDemuxer> MediaSourceDemuxer::GetTrackDemuxer(
+    TrackType aType, uint32_t aTrackNumber) {
+  RefPtr<TrackBuffersManager> manager = GetManager(aType);
+  if (!manager) {
+    return nullptr;
+  }
+  RefPtr<MediaSourceTrackDemuxer> e =
+      new MediaSourceTrackDemuxer(this, aType, manager);
+  DDLINKCHILD("track demuxer", e.get());
+  mDemuxers.AppendElement(e);
+  return e.forget();
+}
+
+bool MediaSourceDemuxer::IsSeekable() const { return true; }
+
+UniquePtr<EncryptionInfo> MediaSourceDemuxer::GetCrypto() {
+  MonitorAutoLock mon(mMonitor);
+  auto crypto = MakeUnique<EncryptionInfo>();
+  *crypto = mInfo.mCrypto;
+  return crypto;
+}
+
+void MediaSourceDemuxer::AttachSourceBuffer(
+    RefPtr<TrackBuffersManager>& aSourceBuffer) {
+  nsCOMPtr<nsIRunnable> task = NewRunnableMethod<RefPtr<TrackBuffersManager>&&>(
+      "MediaSourceDemuxer::DoAttachSourceBuffer", this,
+      &MediaSourceDemuxer::DoAttachSourceBuffer, aSourceBuffer);
+  nsresult rv = GetTaskQueue()->Dispatch(task.forget());
+  MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(rv));
+  Unused << rv;
+}
+
+void MediaSourceDemuxer::DoAttachSourceBuffer(
+    RefPtr<mozilla::TrackBuffersManager>&& aSourceBuffer) {
+  MOZ_ASSERT(OnTaskQueue());
+  mSourceBuffers.AppendElement(std::move(aSourceBuffer));
+  ScanSourceBuffersForContent();
+}
+
+void MediaSourceDemuxer::DetachSourceBuffer(
+    RefPtr<TrackBuffersManager>& aSourceBuffer) {
+  nsCOMPtr<nsIRunnable> task = NewRunnableMethod<RefPtr<TrackBuffersManager>&&>(
+      "MediaSourceDemuxer::DoDetachSourceBuffer", this,
+      &MediaSourceDemuxer::DoDetachSourceBuffer, aSourceBuffer);
+  nsresult rv = GetTaskQueue()->Dispatch(task.forget());
+  MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(rv));
+  Unused << rv;
+}
+
+void MediaSourceDemuxer::DoDetachSourceBuffer(
+    RefPtr<TrackBuffersManager>&& aSourceBuffer) {
+  MOZ_ASSERT(OnTaskQueue());
+  mSourceBuffers.RemoveElementsBy(
+      [&aSourceBuffer](const RefPtr<TrackBuffersManager> aLinkedSourceBuffer) {
+        return aLinkedSourceBuffer == aSourceBuffer;
+      });
+  {
+    MonitorAutoLock mon(mMonitor);
+    if (aSourceBuffer == mAudioTrack) {
+      mAudioTrack = nullptr;
+    }
+    if (aSourceBuffer == mVideoTrack) {
+      mVideoTrack = nullptr;
+    }
+  }
+
+  for (auto& demuxer : mDemuxers) {
+    if (demuxer->HasManager(aSourceBuffer)) {
+      demuxer->DetachManager();
+    }
+  }
+  ScanSourceBuffersForContent();
+}
+
+TrackInfo* MediaSourceDemuxer::GetTrackInfo(TrackType aTrack) {
+  MonitorAutoLock mon(mMonitor);
+  switch (aTrack) {
+    case TrackType::kAudioTrack:
+      return &mInfo.mAudio;
+    case TrackType::kVideoTrack:
+      return &mInfo.mVideo;
+    default:
+      return nullptr;
+  }
+}
+
+RefPtr<TrackBuffersManager> MediaSourceDemuxer::GetManager(TrackType aTrack) {
+  MonitorAutoLock mon(mMonitor);
+  switch (aTrack) {
+    case TrackType::kAudioTrack:
+      return mAudioTrack;
+    case TrackType::kVideoTrack:
+      return mVideoTrack;
+    default:
+      return nullptr;
+  }
+}
+
+MediaSourceDemuxer::~MediaSourceDemuxer() {
+  mInitPromise.RejectIfExists(NS_ERROR_DOM_MEDIA_CANCELED, __func__);
+}
+
+RefPtr<GenericPromise> MediaSourceDemuxer::GetDebugInfo(
+    dom::MediaSourceDemuxerDebugInfo& aInfo) const {
+  MonitorAutoLock mon(mMonitor);
+  nsTArray<RefPtr<GenericPromise>> promises;
+  if (mAudioTrack) {
+    promises.AppendElement(mAudioTrack->RequestDebugInfo(aInfo.mAudioTrack));
+  }
+  if (mVideoTrack) {
+    promises.AppendElement(mVideoTrack->RequestDebugInfo(aInfo.mVideoTrack));
+  }
+  return GenericPromise::All(GetCurrentSerialEventTarget(), promises)
+      ->Then(
+          GetCurrentSerialEventTarget(), __func__,
+          []() { return GenericPromise::CreateAndResolve(true, __func__); },
+          [] {
+            return GenericPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
+          });
+}
+
+MediaSourceTrackDemuxer::MediaSourceTrackDemuxer(MediaSourceDemuxer* aParent,
+                                                 TrackInfo::TrackType aType,
+                                                 TrackBuffersManager* aManager)
+    : mParent(aParent),
+      mTaskQueue(mParent->GetTaskQueue()),
+      mType(aType),
+      mMonitor("MediaSourceTrackDemuxer"),
+      mManager(aManager),
+      mReset(true),
+      mPreRoll(TimeUnit::FromMicroseconds(
+          OpusDataDecoder::IsOpus(mParent->GetTrackInfo(mType)->mMimeType) ||
+                  VorbisDataDecoder::IsVorbis(
+                      mParent->GetTrackInfo(mType)->mMimeType)
+              ? 80000
+          : mParent->GetTrackInfo(mType)->mMimeType.EqualsLiteral(
+                "audio/mp4a-latm")
+              // AAC encoder delay is by default 2112 audio frames.
+              // See
+              // https://developer.apple.com/library/content/documentation/QuickTime/QTFF/QTFFAppenG/QTFFAppenG.html
+              // So we always seek 2112 frames
+              ? (2112 * 1000000ULL /
+                 mParent->GetTrackInfo(mType)->GetAsAudioInfo()->mRate)
+              : 0)) {
+  MOZ_ASSERT(mParent);
+  MOZ_ASSERT(mTaskQueue);
+}
+
+UniquePtr<TrackInfo> MediaSourceTrackDemuxer::GetInfo() const {
+  return mParent->GetTrackInfo(mType)->Clone();
+}
+
+RefPtr<MediaSourceTrackDemuxer::SeekPromise> MediaSourceTrackDemuxer::Seek(
+    const TimeUnit& aTime) {
+  MOZ_ASSERT(mParent, "Called after BreackCycle()");
+  return InvokeAsync(mParent->GetTaskQueue(), this, __func__,
+                     &MediaSourceTrackDemuxer::DoSeek, aTime);
+}
+
+RefPtr<MediaSourceTrackDemuxer::SamplesPromise>
+MediaSourceTrackDemuxer::GetSamples(int32_t aNumSamples) {
+  MOZ_ASSERT(mParent, "Called after BreackCycle()");
+  return InvokeAsync(mParent->GetTaskQueue(), this, __func__,
+                     &MediaSourceTrackDemuxer::DoGetSamples, aNumSamples);
+}
+
+void MediaSourceTrackDemuxer::Reset() {
+  MOZ_ASSERT(mParent, "Called after BreackCycle()");
+  RefPtr<MediaSourceTrackDemuxer> self = this;
+  nsCOMPtr<nsIRunnable> task =
+      NS_NewRunnableFunction("MediaSourceTrackDemuxer::Reset", [self]() {
+        self->mNextSample.reset();
+        self->mReset = true;
+        if (!self->mManager) {
+          return;
+        }
+        MOZ_ASSERT(self->OnTaskQueue());
+        self->mManager->Seek(self->mType, TimeUnit::Zero(), TimeUnit::Zero());
+        {
+          MonitorAutoLock mon(self->mMonitor);
+          self->mNextRandomAccessPoint =
+              self->mManager->GetNextRandomAccessPoint(
+                  self->mType, MediaSourceDemuxer::EOS_FUZZ);
+        }
+      });
+  nsresult rv = mParent->GetTaskQueue()->Dispatch(task.forget());
+  MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(rv));
+  Unused << rv;
+}
+
+nsresult MediaSourceTrackDemuxer::GetNextRandomAccessPoint(TimeUnit* aTime) {
+  MonitorAutoLock mon(mMonitor);
+  *aTime = mNextRandomAccessPoint;
+  return NS_OK;
+}
+
+RefPtr<MediaSourceTrackDemuxer::SkipAccessPointPromise>
+MediaSourceTrackDemuxer::SkipToNextRandomAccessPoint(
+    const TimeUnit& aTimeThreshold) {
+  return InvokeAsync(mParent->GetTaskQueue(), this, __func__,
+                     &MediaSourceTrackDemuxer::DoSkipToNextRandomAccessPoint,
+                     aTimeThreshold);
+}
+
+media::TimeIntervals MediaSourceTrackDemuxer::GetBuffered() {
+  MonitorAutoLock mon(mMonitor);
+  if (!mManager) {
+    return media::TimeIntervals();
+  }
+  return mManager->Buffered();
+}
+
+void MediaSourceTrackDemuxer::BreakCycles() {
+  RefPtr<MediaSourceTrackDemuxer> self = this;
+  nsCOMPtr<nsIRunnable> task =
+      NS_NewRunnableFunction("MediaSourceTrackDemuxer::BreakCycles", [self]() {
+        self->DetachManager();
+        self->mParent = nullptr;
+      });
+  nsresult rv = mParent->GetTaskQueue()->Dispatch(task.forget());
+  MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(rv));
+  Unused << rv;
+}
+
+RefPtr<MediaSourceTrackDemuxer::SeekPromise> MediaSourceTrackDemuxer::DoSeek(
+    const TimeUnit& aTime) {
+  if (!mManager) {
+    return SeekPromise::CreateAndReject(
+        MediaResult(NS_ERROR_DOM_MEDIA_CANCELED,
+                    RESULT_DETAIL("manager is detached.")),
+        __func__);
+  }
+
+  MOZ_ASSERT(OnTaskQueue());
+  TimeIntervals buffered = mManager->Buffered(mType);
+  // Fuzz factor represents a +/- threshold. So when seeking it allows the gap
+  // to be twice as big as the fuzz value. We only want to allow EOS_FUZZ gap.
+  buffered.SetFuzz(MediaSourceDemuxer::EOS_FUZZ / 2);
+  TimeUnit seekTime = std::max(aTime - mPreRoll, TimeUnit::Zero());
+
+  if (mManager->IsEnded() && seekTime >= buffered.GetEnd()) {
+    // We're attempting to seek past the end time. Cap seekTime so that we seek
+    // to the last sample instead.
+    seekTime = std::max(mManager->HighestStartTime(mType) - mPreRoll,
+                        TimeUnit::Zero());
+  }
+  if (!buffered.ContainsWithStrictEnd(seekTime)) {
+    if (!buffered.ContainsWithStrictEnd(aTime)) {
+      // We don't have the data to seek to.
+      return SeekPromise::CreateAndReject(NS_ERROR_DOM_MEDIA_WAITING_FOR_DATA,
+                                          __func__);
+    }
+    // Theoretically we should reject the promise with WAITING_FOR_DATA,
+    // however, to avoid unwanted regressions we assume that if at this time
+    // we don't have the wanted data it won't come later.
+    // Instead of using the pre-rolled time, use the earliest time available in
+    // the interval.
+    TimeIntervals::IndexType index = buffered.Find(aTime);
+    MOZ_ASSERT(index != TimeIntervals::NoIndex);
+    seekTime = buffered[index].mStart;
+  }
+  seekTime = mManager->Seek(mType, seekTime, MediaSourceDemuxer::EOS_FUZZ);
+  MediaResult result = NS_OK;
+  RefPtr<MediaRawData> sample =
+      mManager->GetSample(mType, TimeUnit::Zero(), result);
+  MOZ_ASSERT(NS_SUCCEEDED(result) && sample);
+  mNextSample = Some(sample);
+  mReset = false;
+  {
+    MonitorAutoLock mon(mMonitor);
+    mNextRandomAccessPoint =
+        mManager->GetNextRandomAccessPoint(mType, MediaSourceDemuxer::EOS_FUZZ);
+  }
+  return SeekPromise::CreateAndResolve(seekTime, __func__);
+}
+
+RefPtr<MediaSourceTrackDemuxer::SamplesPromise>
+MediaSourceTrackDemuxer::DoGetSamples(int32_t aNumSamples) {
+  if (!mManager) {
+    return SamplesPromise::CreateAndReject(
+        MediaResult(NS_ERROR_DOM_MEDIA_CANCELED,
+                    RESULT_DETAIL("manager is detached.")),
+        __func__);
+  }
+
+  MOZ_ASSERT(OnTaskQueue());
+  if (mReset) {
+    // If a reset was recently performed, we ensure that the data
+    // we are about to retrieve is still available.
+    TimeIntervals buffered = mManager->Buffered(mType);
+    if (buffered.IsEmpty() && mManager->IsEnded()) {
+      return SamplesPromise::CreateAndReject(NS_ERROR_DOM_MEDIA_END_OF_STREAM,
+                                             __func__);
+    }
+
+    // We use a larger fuzz to determine the presentation start
+    // time than the fuzz we use to determine acceptable gaps between
+    // frames. This is needed to fix embedded video issues as seen in the wild
+    // from different muxed stream start times.
+    // See: https://www.w3.org/TR/media-source-2/#presentation-start-time
+    buffered.SetFuzz(MediaSourceDemuxer::EOS_FUZZ_START);
+    if (!buffered.ContainsWithStrictEnd(TimeUnit::Zero())) {
+      return SamplesPromise::CreateAndReject(
+          NS_ERROR_DOM_MEDIA_WAITING_FOR_DATA, __func__);
+    }
+    mReset = false;
+  }
+  RefPtr<MediaRawData> sample;
+  if (mNextSample) {
+    sample = mNextSample.ref();
+    mNextSample.reset();
+  } else {
+    MediaResult result = NS_OK;
+    sample = mManager->GetSample(mType, MediaSourceDemuxer::EOS_FUZZ, result);
+    if (!sample) {
+      if (result == NS_ERROR_DOM_MEDIA_END_OF_STREAM ||
+          result == NS_ERROR_DOM_MEDIA_WAITING_FOR_DATA) {
+        return SamplesPromise::CreateAndReject(
+            (result == NS_ERROR_DOM_MEDIA_END_OF_STREAM && mManager->IsEnded())
+                ? NS_ERROR_DOM_MEDIA_END_OF_STREAM
+                : NS_ERROR_DOM_MEDIA_WAITING_FOR_DATA,
+            __func__);
+      }
+      return SamplesPromise::CreateAndReject(result, __func__);
+    }
+  }
+  RefPtr<SamplesHolder> samples = new SamplesHolder;
+  samples->AppendSample(sample);
+  {
+    MonitorAutoLock mon(mMonitor);  // spurious warning will be given
+    // Diagnostic asserts for bug 1810396
+    MOZ_DIAGNOSTIC_ASSERT(sample, "Invalid sample pointer found!");
+    MOZ_DIAGNOSTIC_ASSERT(sample->HasValidTime(), "Invalid sample time found!");
+    if (!sample) {
+      return SamplesPromise::CreateAndReject(NS_ERROR_NULL_POINTER, __func__);
+    }
+    if (mNextRandomAccessPoint <= sample->mTime) {
+      mNextRandomAccessPoint = mManager->GetNextRandomAccessPoint(
+          mType, MediaSourceDemuxer::EOS_FUZZ);
+    }
+  }
+  return SamplesPromise::CreateAndResolve(samples, __func__);
+}
+
+RefPtr<MediaSourceTrackDemuxer::SkipAccessPointPromise>
+MediaSourceTrackDemuxer::DoSkipToNextRandomAccessPoint(
+    const TimeUnit& aTimeThreadshold) {
+  if (!mManager) {
+    return SkipAccessPointPromise::CreateAndReject(
+        SkipFailureHolder(MediaResult(NS_ERROR_DOM_MEDIA_CANCELED,
+                                      RESULT_DETAIL("manager is detached.")),
+                          0),
+        __func__);
+  }
+
+  MOZ_ASSERT(OnTaskQueue());
+  uint32_t parsed = 0;
+  // Ensure that the data we are about to skip to is still available.
+  TimeIntervals buffered = mManager->Buffered(mType);
+  buffered.SetFuzz(MediaSourceDemuxer::EOS_FUZZ / 2);
+  if (buffered.ContainsWithStrictEnd(aTimeThreadshold)) {
+    bool found;
+    parsed = mManager->SkipToNextRandomAccessPoint(
+        mType, aTimeThreadshold, MediaSourceDemuxer::EOS_FUZZ, found);
+    if (found) {
+      return SkipAccessPointPromise::CreateAndResolve(parsed, __func__);
+    }
+  }
+  SkipFailureHolder holder(mManager->IsEnded()
+                               ? NS_ERROR_DOM_MEDIA_END_OF_STREAM
+                               : NS_ERROR_DOM_MEDIA_WAITING_FOR_DATA,
+                           parsed);
+  return SkipAccessPointPromise::CreateAndReject(holder, __func__);
+}
+
+bool MediaSourceTrackDemuxer::HasManager(TrackBuffersManager* aManager) const {
+  MOZ_ASSERT(OnTaskQueue());
+  return mManager == aManager;
+}
+
+void MediaSourceTrackDemuxer::DetachManager() {
+  MOZ_ASSERT(OnTaskQueue());
+  MonitorAutoLock mon(mMonitor);
+  mManager = nullptr;
+}
+
+}  // namespace mozilla
diff --git a/dom/media/mediasource/MediaSourceDemuxer.h b/dom/media/mediasource/MediaSourceDemuxer.h
new file mode 100644
index 0000000000..d878298461
--- /dev/null
+++ b/dom/media/mediasource/MediaSourceDemuxer.h
@@ -0,0 +1,171 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#if !defined(MediaSourceDemuxer_h_)
+#  define MediaSourceDemuxer_h_
+
+#  include "MediaDataDemuxer.h"
+#  include "MediaResource.h"
+#  include "MediaSource.h"
+#  include "TrackBuffersManager.h"
+#  include "mozilla/Atomics.h"
+#  include "mozilla/Maybe.h"
+#  include "mozilla/Monitor.h"
+#  include "mozilla/TaskQueue.h"
+#  include "mozilla/dom/MediaDebugInfoBinding.h"
+
+namespace mozilla {
+
+class AbstractThread;
+class MediaResult;
+class MediaSourceTrackDemuxer;
+
+DDLoggedTypeDeclNameAndBase(MediaSourceDemuxer, MediaDataDemuxer);
+DDLoggedTypeNameAndBase(MediaSourceTrackDemuxer, MediaTrackDemuxer);
+
+class MediaSourceDemuxer : public MediaDataDemuxer,
+                           public DecoderDoctorLifeLogger<MediaSourceDemuxer> {
+ public:
+  explicit MediaSourceDemuxer(AbstractThread* aAbstractMainThread);
+
+  RefPtr<InitPromise> Init() override;
+
+  uint32_t GetNumberTracks(TrackInfo::TrackType aType) const override;
+
+  already_AddRefed<MediaTrackDemuxer> GetTrackDemuxer(
+      TrackInfo::TrackType aType, uint32_t aTrackNumber) override;
+
+  bool IsSeekable() const override;
+
+  UniquePtr<EncryptionInfo> GetCrypto() override;
+
+  bool ShouldComputeStartTime() const override { return false; }
+
+  /* interface for TrackBuffersManager */
+  void AttachSourceBuffer(RefPtr<TrackBuffersManager>& aSourceBuffer);
+  void DetachSourceBuffer(RefPtr<TrackBuffersManager>& aSourceBuffer);
+  TaskQueue* GetTaskQueue() { return mTaskQueue; }
+  void NotifyInitDataArrived();
+
+  // Populates aInfo with info describing the state of the MediaSource internal
+  // buffered data. Used for debugging purposes.
+  // aInfo should *not* be accessed until the returned promise has been resolved
+  // or rejected.
+  RefPtr<GenericPromise> GetDebugInfo(
+      dom::MediaSourceDemuxerDebugInfo& aInfo) const;
+
+  void AddSizeOfResources(MediaSourceDecoder::ResourceSizes* aSizes);
+
+  // Gap allowed between frames.
+  // Due to inaccuracies in determining buffer end
+  // frames (Bug 1065207). This value is based on videos seen in the wild.
+  static constexpr media::TimeUnit EOS_FUZZ =
+      media::TimeUnit::FromMicroseconds(500000);
+
+  // Largest gap allowed between muxed streams with different
+  // start times. The specs suggest up to a "reasonably short" gap of
+  // one second. We conservatively choose to allow a gap up to a bit over
+  // a half-second here, which is still twice our previous effective value
+  // and should resolve embedded playback issues on Twitter, DokiDoki, etc.
+  // See: https://www.w3.org/TR/media-source-2/#presentation-start-time
+  static constexpr media::TimeUnit EOS_FUZZ_START =
+      media::TimeUnit::FromMicroseconds(550000);
+
+ private:
+  ~MediaSourceDemuxer();
+  friend class MediaSourceTrackDemuxer;
+  // Scan source buffers and update information.
+  bool ScanSourceBuffersForContent();
+  RefPtr<TrackBuffersManager> GetManager(TrackInfo::TrackType aType);
+  TrackInfo* GetTrackInfo(TrackInfo::TrackType);
+  void DoAttachSourceBuffer(RefPtr<TrackBuffersManager>&& aSourceBuffer);
+  void DoDetachSourceBuffer(RefPtr<TrackBuffersManager>&& aSourceBuffer);
+  bool OnTaskQueue() {
+    return !GetTaskQueue() || GetTaskQueue()->IsCurrentThreadIn();
+  }
+
+  RefPtr<TaskQueue> mTaskQueue;
+  nsTArray<RefPtr<MediaSourceTrackDemuxer>> mDemuxers;
+
+  nsTArray<RefPtr<TrackBuffersManager>> mSourceBuffers;
+
+  MozPromiseHolder<InitPromise> mInitPromise;
+
+  // Monitor to protect members below across multiple threads.
+  mutable Monitor mMonitor MOZ_UNANNOTATED;
+  RefPtr<TrackBuffersManager> mAudioTrack;
+  RefPtr<TrackBuffersManager> mVideoTrack;
+  MediaInfo mInfo;
+};
+
+class MediaSourceTrackDemuxer
+    : public MediaTrackDemuxer,
+      public DecoderDoctorLifeLogger<MediaSourceTrackDemuxer> {
+ public:
+  MediaSourceTrackDemuxer(MediaSourceDemuxer* aParent,
+                          TrackInfo::TrackType aType,
+                          TrackBuffersManager* aManager);
+
+  UniquePtr<TrackInfo> GetInfo() const override;
+
+  RefPtr<SeekPromise> Seek(const media::TimeUnit& aTime) override;
+
+  RefPtr<SamplesPromise> GetSamples(int32_t aNumSamples = 1) override;
+
+  void Reset() override;
+
+  nsresult GetNextRandomAccessPoint(media::TimeUnit* aTime) override;
+
+  RefPtr<SkipAccessPointPromise> SkipToNextRandomAccessPoint(
+      const media::TimeUnit& aTimeThreshold) override;
+
+  media::TimeIntervals GetBuffered() override;
+
+  void BreakCycles() override;
+
+  bool GetSamplesMayBlock() const override { return false; }
+
+  bool HasManager(TrackBuffersManager* aManager) const;
+  void DetachManager();
+
+ private:
+  bool OnTaskQueue() const { return mTaskQueue->IsCurrentThreadIn(); }
+
+  RefPtr<SeekPromise> DoSeek(const media::TimeUnit& aTime);
+  RefPtr<SamplesPromise> DoGetSamples(int32_t aNumSamples);
+  RefPtr<SkipAccessPointPromise> DoSkipToNextRandomAccessPoint(
+      const media::TimeUnit& aTimeThreadshold);
+  already_AddRefed<MediaRawData> GetSample(MediaResult& aError);
+  // Return the timestamp of the next keyframe after mLastSampleIndex.
+  media::TimeUnit GetNextRandomAccessPoint();
+
+  RefPtr<MediaSourceDemuxer> mParent;
+  const RefPtr<TaskQueue> mTaskQueue;
+
+  TrackInfo::TrackType mType;
+  // Monitor protecting members below accessed from multiple threads.
+  Monitor mMonitor MOZ_UNANNOTATED;
+  media::TimeUnit mNextRandomAccessPoint;
+  // Would be accessed in MFR's demuxer proxy task queue and TaskQueue, and
+  // only be set on the TaskQueue. It can be accessed while on TaskQueue without
+  // the need for the lock.
+  RefPtr<TrackBuffersManager> mManager;
+
+  // Only accessed on TaskQueue
+  Maybe<RefPtr<MediaRawData>> mNextSample;
+  // Set to true following a reset. Ensure that the next sample demuxed
+  // is available at position 0.
+  // Only accessed on TaskQueue
+  bool mReset;
+
+  // Amount of pre-roll time when seeking.
+  // Set to 80ms if track is Opus.
+  const media::TimeUnit mPreRoll;
+};
+
+}  // namespace mozilla
+
+#endif
diff --git a/dom/media/mediasource/MediaSourceUtils.cpp b/dom/media/mediasource/MediaSourceUtils.cpp
new file mode 100644
index 0000000000..915c338af0
--- /dev/null
+++ b/dom/media/mediasource/MediaSourceUtils.cpp
@@ -0,0 +1,31 @@
+/* -*- mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include "MediaSourceUtils.h"
+
+#include "mozilla/Logging.h"
+#include "nsPrintfCString.h"
+
+namespace mozilla {
+
+nsCString DumpTimeRanges(const media::TimeIntervals& aRanges) {
+  nsCString dump;
+
+  dump = "[";
+
+  for (uint32_t i = 0; i < aRanges.Length(); ++i) {
+    if (i > 0) {
+      dump += ", ";
+    }
+    dump += nsPrintfCString("(%f, %f)", aRanges.Start(i).ToSeconds(),
+                            aRanges.End(i).ToSeconds());
+  }
+
+  dump += "]";
+
+  return dump;
+}
+
+}  // namespace mozilla
diff --git a/dom/media/mediasource/MediaSourceUtils.h b/dom/media/mediasource/MediaSourceUtils.h
new file mode 100644
index 0000000000..28ec02de8c
--- /dev/null
+++ b/dom/media/mediasource/MediaSourceUtils.h
@@ -0,0 +1,19 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_MEDIASOURCEUTILS_H_
+#define MOZILLA_MEDIASOURCEUTILS_H_
+
+#include "nsString.h"
+#include "TimeUnits.h"
+
+namespace mozilla {
+
+nsCString DumpTimeRanges(const media::TimeIntervals& aRanges);
+
+}  // namespace mozilla
+
+#endif /* MOZILLA_MEDIASOURCEUTILS_H_ */
diff --git a/dom/media/mediasource/ResourceQueue.cpp b/dom/media/mediasource/ResourceQueue.cpp
new file mode 100644
index 0000000000..717638b5c8
--- /dev/null
+++ b/dom/media/mediasource/ResourceQueue.cpp
@@ -0,0 +1,204 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ResourceQueue.h"
+#include "MediaData.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/IntegerPrintfMacros.h"
+#include "mozilla/Logging.h"
+#include "mozilla/Sprintf.h"
+#include "mozilla/Unused.h"
+
+extern mozilla::LogModule* GetSourceBufferResourceLog();
+
+#define SBR_DEBUG(arg, ...)                                       \
+  MOZ_LOG(GetSourceBufferResourceLog(), mozilla::LogLevel::Debug, \
+          ("ResourceQueue(%p)::%s: " arg, this, __func__, ##__VA_ARGS__))
+#define SBR_DEBUGV(arg, ...)                                        \
+  MOZ_LOG(GetSourceBufferResourceLog(), mozilla::LogLevel::Verbose, \
+          ("ResourceQueue(%p)::%s: " arg, this, __func__, ##__VA_ARGS__))
+
+namespace mozilla {
+
+ResourceItem::ResourceItem(const MediaSpan& aData, uint64_t aOffset)
+    : mData(aData), mOffset(aOffset) {}
+
+size_t ResourceItem::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const {
+  return aMallocSizeOf(this);
+}
+
+class ResourceQueueDeallocator : public nsDequeFunctor<ResourceItem> {
+  void operator()(ResourceItem* aObject) override { delete aObject; }
+};
+
+ResourceQueue::ResourceQueue()
+    : nsDeque<ResourceItem>(new ResourceQueueDeallocator()),
+      mLogicalLength(0),
+      mOffset(0) {}
+
+uint64_t ResourceQueue::GetOffset() { return mOffset; }
+
+uint64_t ResourceQueue::GetLength() { return mLogicalLength; }
+
+const uint8_t* ResourceQueue::GetContiguousAccess(int64_t aOffset,
+                                                  size_t aSize) {
+  uint32_t offset = 0;
+  uint32_t start = GetAtOffset(aOffset, &offset);
+  if (start >= GetSize()) {
+    return nullptr;
+  }
+  ResourceItem* item = ResourceAt(start);
+  if (offset + aSize > item->mData.Length()) {
+    return nullptr;
+  }
+  return item->mData.Elements() + offset;
+}
+
+void ResourceQueue::CopyData(uint64_t aOffset, uint32_t aCount, char* aDest) {
+  uint32_t offset = 0;
+  uint32_t start = GetAtOffset(aOffset, &offset);
+  size_t i = start;
+  while (i < uint32_t(GetSize()) && aCount > 0) {
+    ResourceItem* item = ResourceAt(i++);
+    uint32_t bytes = std::min(aCount, uint32_t(item->mData.Length() - offset));
+    if (bytes != 0) {
+      memcpy(aDest, item->mData.Elements() + offset, bytes);
+      offset = 0;
+      aCount -= bytes;
+      aDest += bytes;
+    }
+  }
+}
+
+void ResourceQueue::AppendItem(const MediaSpan& aData) {
+  uint64_t offset = mLogicalLength;
+  mLogicalLength += aData.Length();
+  Push(new ResourceItem(aData, offset));
+}
+
+uint32_t ResourceQueue::Evict(uint64_t aOffset, uint32_t aSizeToEvict) {
+  SBR_DEBUG("Evict(aOffset=%" PRIu64 ", aSizeToEvict=%u)", aOffset,
+            aSizeToEvict);
+  return EvictBefore(std::min(aOffset, mOffset + (uint64_t)aSizeToEvict));
+}
+
+uint32_t ResourceQueue::EvictBefore(uint64_t aOffset) {
+  SBR_DEBUG("EvictBefore(%" PRIu64 ")", aOffset);
+  uint32_t evicted = 0;
+  while (GetSize()) {
+    ResourceItem* item = ResourceAt(0);
+    SBR_DEBUG("item=%p length=%zu offset=%" PRIu64, item, item->mData.Length(),
+              mOffset);
+    if (item->mData.Length() + mOffset >= aOffset) {
+      if (aOffset <= mOffset) {
+        break;
+      }
+      uint32_t offset = aOffset - mOffset;
+      mOffset += offset;
+      evicted += offset;
+      item->mData.RemoveFront(offset);
+      item->mOffset += offset;
+      break;
+    }
+    mOffset += item->mData.Length();
+    evicted += item->mData.Length();
+    delete PopFront();
+  }
+  return evicted;
+}
+
+uint32_t ResourceQueue::EvictAll() {
+  SBR_DEBUG("EvictAll()");
+  uint32_t evicted = 0;
+  while (GetSize()) {
+    ResourceItem* item = ResourceAt(0);
+    SBR_DEBUG("item=%p length=%zu offset=%" PRIu64, item, item->mData.Length(),
+              mOffset);
+    mOffset += item->mData.Length();
+    evicted += item->mData.Length();
+    delete PopFront();
+  }
+  return evicted;
+}
+
+size_t ResourceQueue::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const {
+  // Calculate the size of the internal deque.
+  size_t size = nsDeque<ResourceItem>::SizeOfExcludingThis(aMallocSizeOf);
+
+  // Sum the ResourceItems. The ResourceItems's MediaSpans may share the
+  // same underlying MediaByteBuffers, so we need to de-dupe the buffers
+  // in order to report an accurate size.
+  nsTArray<MediaByteBuffer*> buffers;
+  for (uint32_t i = 0; i < uint32_t(GetSize()); ++i) {
+    const ResourceItem* item = ResourceAt(i);
+    size += item->SizeOfIncludingThis(aMallocSizeOf);
+    if (!buffers.Contains(item->mData.Buffer())) {
+      buffers.AppendElement(item->mData.Buffer());
+    }
+  }
+
+  for (MediaByteBuffer* buffer : buffers) {
+    size += buffer->ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  return size;
+}
+
+#if defined(DEBUG)
+void ResourceQueue::Dump(const char* aPath) {
+  for (uint32_t i = 0; i < uint32_t(GetSize()); ++i) {
+    ResourceItem* item = ResourceAt(i);
+
+    char buf[255];
+    SprintfLiteral(buf, "%s/%08u.bin", aPath, i);
+    FILE* fp = fopen(buf, "wb");
+    if (!fp) {
+      return;
+    }
+    Unused << fwrite(item->mData.Elements(), item->mData.Length(), 1, fp);
+    fclose(fp);
+  }
+}
+#endif
+
+ResourceItem* ResourceQueue::ResourceAt(uint32_t aIndex) const {
+  return static_cast<ResourceItem*>(ObjectAt(aIndex));
+}
+
+uint32_t ResourceQueue::GetAtOffset(uint64_t aOffset,
+                                    uint32_t* aResourceOffset) const {
+  MOZ_RELEASE_ASSERT(aOffset >= mOffset);
+
+  size_t hi = GetSize();
+  size_t lo = 0;
+  while (lo < hi) {
+    size_t mid = lo + (hi - lo) / 2;
+    const ResourceItem* resource = ResourceAt(mid);
+    if (resource->mOffset <= aOffset &&
+        aOffset < resource->mOffset + resource->mData.Length()) {
+      if (aResourceOffset) {
+        *aResourceOffset = aOffset - resource->mOffset;
+      }
+      return uint32_t(mid);
+    }
+    if (resource->mOffset + resource->mData.Length() <= aOffset) {
+      lo = mid + 1;
+    } else {
+      hi = mid;
+    }
+  }
+
+  return uint32_t(GetSize());
+}
+
+ResourceItem* ResourceQueue::PopFront() {
+  return nsDeque<ResourceItem>::PopFront();
+}
+
+#undef SBR_DEBUG
+#undef SBR_DEBUGV
+
+}  // namespace mozilla
diff --git a/dom/media/mediasource/ResourceQueue.h b/dom/media/mediasource/ResourceQueue.h
new file mode 100644
index 0000000000..efd1e0c20a
--- /dev/null
+++ b/dom/media/mediasource/ResourceQueue.h
@@ -0,0 +1,88 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_RESOURCEQUEUE_H_
+#define MOZILLA_RESOURCEQUEUE_H_
+
+#include "nsDeque.h"
+#include "MediaSpan.h"
+
+namespace mozilla {
+
+class ErrorResult;
+
+// A SourceBufferResource has a queue containing the data that is appended
+// to it. The queue holds instances of ResourceItem which is an array of the
+// bytes. Appending data to the SourceBufferResource pushes this onto the
+// queue.
+
+// Data is evicted once it reaches a size threshold. This pops the items off
+// the front of the queue and deletes it.  If an eviction happens then the
+// MediaSource is notified (done in SourceBuffer::AppendData) which then
+// requests all SourceBuffers to evict data up to approximately the same
+// timepoint.
+
+struct ResourceItem {
+  ResourceItem(const MediaSpan& aData, uint64_t aOffset);
+  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const;
+  MediaSpan mData;
+  uint64_t mOffset;
+};
+
+class ResourceQueue : private nsDeque<ResourceItem> {
+ public:
+  ResourceQueue();
+
+  // Returns the logical byte offset of the start of the data.
+  uint64_t GetOffset();
+
+  // Returns the length of all items in the queue plus the offset.
+  // This is the logical length of the resource.
+  uint64_t GetLength();
+
+  // Copies aCount bytes from aOffset in the queue into aDest.
+  void CopyData(uint64_t aOffset, uint32_t aCount, char* aDest);
+
+  void AppendItem(const MediaSpan& aData);
+
+  // Tries to evict at least aSizeToEvict from the queue up until
+  // aOffset. Returns amount evicted.
+  uint32_t Evict(uint64_t aOffset, uint32_t aSizeToEvict);
+
+  uint32_t EvictBefore(uint64_t aOffset);
+
+  uint32_t EvictAll();
+
+  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const;
+
+#if defined(DEBUG)
+  void Dump(const char* aPath);
+#endif
+
+  const uint8_t* GetContiguousAccess(int64_t aOffset, size_t aSize);
+
+ private:
+  ResourceItem* ResourceAt(uint32_t aIndex) const;
+
+  // Returns the index of the resource that contains the given
+  // logical offset. aResourceOffset will contain the offset into
+  // the resource at the given index returned if it is not null.  If
+  // no such resource exists, returns GetSize() and aOffset is
+  // untouched.
+  uint32_t GetAtOffset(uint64_t aOffset, uint32_t* aResourceOffset) const;
+
+  ResourceItem* PopFront();
+
+  // Logical length of the resource.
+  uint64_t mLogicalLength;
+
+  // Logical offset into the resource of the first element in the queue.
+  uint64_t mOffset;
+};
+
+}  // namespace mozilla
+
+#endif /* MOZILLA_RESOURCEQUEUE_H_ */
diff --git a/dom/media/mediasource/SourceBuffer.cpp b/dom/media/mediasource/SourceBuffer.cpp
new file mode 100644
index 0000000000..dcdd2008b2
--- /dev/null
+++ b/dom/media/mediasource/SourceBuffer.cpp
@@ -0,0 +1,767 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "SourceBuffer.h"
+
+#include "AsyncEventRunner.h"
+#include "MediaData.h"
+#include "MediaSourceDemuxer.h"
+#include "MediaSourceUtils.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/FloatingPoint.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/dom/MediaSourceBinding.h"
+#include "mozilla/dom/TimeRanges.h"
+#include "nsError.h"
+#include "nsIRunnable.h"
+#include "nsThreadUtils.h"
+#include "mozilla/Logging.h"
+#include <time.h>
+#include "TimeUnits.h"
+
+struct JSContext;
+class JSObject;
+
+extern mozilla::LogModule* GetMediaSourceLog();
+extern mozilla::LogModule* GetMediaSourceAPILog();
+
+#define MSE_DEBUG(arg, ...)                                                  \
+  DDMOZ_LOG(GetMediaSourceLog(), mozilla::LogLevel::Debug, "(%s)::%s: " arg, \
+            mType.OriginalString().Data(), __func__, ##__VA_ARGS__)
+#define MSE_DEBUGV(arg, ...)                                                   \
+  DDMOZ_LOG(GetMediaSourceLog(), mozilla::LogLevel::Verbose, "(%s)::%s: " arg, \
+            mType.OriginalString().Data(), __func__, ##__VA_ARGS__)
+#define MSE_API(arg, ...)                                              \
+  DDMOZ_LOG(GetMediaSourceAPILog(), mozilla::LogLevel::Debug,          \
+            "(%s)::%s: " arg, mType.OriginalString().Data(), __func__, \
+            ##__VA_ARGS__)
+
+namespace mozilla {
+
+using media::TimeUnit;
+typedef SourceBufferAttributes::AppendState AppendState;
+
+namespace dom {
+
+void SourceBuffer::SetMode(SourceBufferAppendMode aMode, ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_API("SetMode(aMode=%" PRIu32 ")", static_cast<uint32_t>(aMode));
+  if (!IsAttached() || mUpdating) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+  if (mCurrentAttributes.mGenerateTimestamps &&
+      aMode == SourceBufferAppendMode::Segments) {
+    aRv.ThrowTypeError(
+        "Can't set mode to \"segments\" when the byte stream generates "
+        "timestamps");
+    return;
+  }
+  MOZ_ASSERT(mMediaSource->ReadyState() != MediaSourceReadyState::Closed);
+  if (mMediaSource->ReadyState() == MediaSourceReadyState::Ended) {
+    mMediaSource->SetReadyState(MediaSourceReadyState::Open);
+  }
+  if (mCurrentAttributes.GetAppendState() ==
+      AppendState::PARSING_MEDIA_SEGMENT) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+
+  if (aMode == SourceBufferAppendMode::Sequence) {
+    // Will set GroupStartTimestamp to GroupEndTimestamp.
+    mCurrentAttributes.RestartGroupStartTimestamp();
+  }
+
+  mCurrentAttributes.SetAppendMode(aMode);
+}
+
+void SourceBuffer::SetTimestampOffset(double aTimestampOffset,
+                                      ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_API("SetTimestampOffset(aTimestampOffset=%f)", aTimestampOffset);
+  if (!IsAttached() || mUpdating) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+  MOZ_ASSERT(mMediaSource->ReadyState() != MediaSourceReadyState::Closed);
+  if (mMediaSource->ReadyState() == MediaSourceReadyState::Ended) {
+    mMediaSource->SetReadyState(MediaSourceReadyState::Open);
+  }
+  if (mCurrentAttributes.GetAppendState() ==
+      AppendState::PARSING_MEDIA_SEGMENT) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+  mCurrentAttributes.SetApparentTimestampOffset(aTimestampOffset);
+  if (mCurrentAttributes.GetAppendMode() == SourceBufferAppendMode::Sequence) {
+    mCurrentAttributes.SetGroupStartTimestamp(
+        mCurrentAttributes.GetTimestampOffset());
+  }
+}
+
+TimeRanges* SourceBuffer::GetBuffered(ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+  // http://w3c.github.io/media-source/index.html#widl-SourceBuffer-buffered
+  // 1. If this object has been removed from the sourceBuffers attribute of the
+  // parent media source then throw an InvalidStateError exception and abort
+  // these steps.
+  if (!IsAttached()) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return nullptr;
+  }
+  bool rangeChanged = true;
+  media::TimeIntervals intersection = mTrackBuffersManager->Buffered();
+  MSE_DEBUGV("intersection=%s", DumpTimeRanges(intersection).get());
+  if (mBuffered) {
+    media::TimeIntervals currentValue(mBuffered->ToTimeIntervals());
+    rangeChanged = (intersection != currentValue);
+    MSE_DEBUGV("currentValue=%s", DumpTimeRanges(currentValue).get());
+  }
+  // 5. If intersection ranges does not contain the exact same range information
+  // as the current value of this attribute, then update the current value of
+  // this attribute to intersection ranges.
+  if (rangeChanged) {
+    mBuffered = new TimeRanges(ToSupports(this), intersection);
+  }
+  // 6. Return the current value of this attribute.
+  return mBuffered;
+}
+
+media::TimeIntervals SourceBuffer::GetTimeIntervals() {
+  return mTrackBuffersManager->Buffered();
+}
+
+void SourceBuffer::SetAppendWindowStart(double aAppendWindowStart,
+                                        ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_API("SetAppendWindowStart(aAppendWindowStart=%f)", aAppendWindowStart);
+  DDLOG(DDLogCategory::API, "SetAppendWindowStart", aAppendWindowStart);
+  if (!IsAttached() || mUpdating) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+  if (aAppendWindowStart < 0 ||
+      aAppendWindowStart >= mCurrentAttributes.GetAppendWindowEnd()) {
+    aRv.ThrowTypeError("Invalid appendWindowStart value");
+    return;
+  }
+  mCurrentAttributes.SetAppendWindowStart(aAppendWindowStart);
+}
+
+void SourceBuffer::SetAppendWindowEnd(double aAppendWindowEnd,
+                                      ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_API("SetAppendWindowEnd(aAppendWindowEnd=%f)", aAppendWindowEnd);
+  DDLOG(DDLogCategory::API, "SetAppendWindowEnd", aAppendWindowEnd);
+  if (!IsAttached() || mUpdating) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+  if (IsNaN(aAppendWindowEnd) ||
+      aAppendWindowEnd <= mCurrentAttributes.GetAppendWindowStart()) {
+    aRv.ThrowTypeError("Invalid appendWindowEnd value");
+    return;
+  }
+  mCurrentAttributes.SetAppendWindowEnd(aAppendWindowEnd);
+}
+
+void SourceBuffer::AppendBuffer(const ArrayBuffer& aData, ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_API("AppendBuffer(ArrayBuffer)");
+  aData.ComputeState();
+  DDLOG(DDLogCategory::API, "AppendBuffer", aData.Length());
+  AppendData(aData.Data(), aData.Length(), aRv);
+}
+
+void SourceBuffer::AppendBuffer(const ArrayBufferView& aData,
+                                ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_API("AppendBuffer(ArrayBufferView)");
+  aData.ComputeState();
+  DDLOG(DDLogCategory::API, "AppendBuffer", aData.Length());
+  AppendData(aData.Data(), aData.Length(), aRv);
+}
+
+already_AddRefed<Promise> SourceBuffer::AppendBufferAsync(
+    const ArrayBuffer& aData, ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  MSE_API("AppendBufferAsync(ArrayBuffer)");
+  aData.ComputeState();
+  DDLOG(DDLogCategory::API, "AppendBufferAsync", aData.Length());
+
+  return AppendDataAsync(aData.Data(), aData.Length(), aRv);
+}
+
+already_AddRefed<Promise> SourceBuffer::AppendBufferAsync(
+    const ArrayBufferView& aData, ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  MSE_API("AppendBufferAsync(ArrayBufferView)");
+  aData.ComputeState();
+  DDLOG(DDLogCategory::API, "AppendBufferAsync", aData.Length());
+
+  return AppendDataAsync(aData.Data(), aData.Length(), aRv);
+}
+
+void SourceBuffer::Abort(ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_API("Abort()");
+  if (!IsAttached()) {
+    DDLOG(DDLogCategory::API, "Abort", NS_ERROR_DOM_INVALID_STATE_ERR);
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+  if (mMediaSource->ReadyState() != MediaSourceReadyState::Open) {
+    DDLOG(DDLogCategory::API, "Abort", NS_ERROR_DOM_INVALID_STATE_ERR);
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+  if (mPendingRemoval.Exists()) {
+    DDLOG(DDLogCategory::API, "Abort", NS_ERROR_DOM_INVALID_STATE_ERR);
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+  DDLOG(DDLogCategory::API, "Abort", NS_OK);
+  AbortBufferAppend();
+  ResetParserState();
+  mCurrentAttributes.SetAppendWindowStart(0);
+  mCurrentAttributes.SetAppendWindowEnd(PositiveInfinity<double>());
+}
+
+void SourceBuffer::AbortBufferAppend() {
+  if (mUpdating) {
+    mCompletionPromise.DisconnectIfExists();
+    if (mPendingAppend.Exists()) {
+      mPendingAppend.Disconnect();
+      mTrackBuffersManager->AbortAppendData();
+    }
+    AbortUpdating();
+  }
+}
+
+void SourceBuffer::ResetParserState() {
+  mTrackBuffersManager->ResetParserState(mCurrentAttributes);
+}
+
+void SourceBuffer::Remove(double aStart, double aEnd, ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_API("Remove(aStart=%f, aEnd=%f)", aStart, aEnd);
+  DDLOG(DDLogCategory::API, "Remove-from", aStart);
+  DDLOG(DDLogCategory::API, "Remove-until", aEnd);
+
+  PrepareRemove(aStart, aEnd, aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+  RangeRemoval(aStart, aEnd);
+}
+
+already_AddRefed<Promise> SourceBuffer::RemoveAsync(double aStart, double aEnd,
+                                                    ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_API("RemoveAsync(aStart=%f, aEnd=%f)", aStart, aEnd);
+  DDLOG(DDLogCategory::API, "Remove-from", aStart);
+  DDLOG(DDLogCategory::API, "Remove-until", aEnd);
+
+  if (!IsAttached()) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIGlobalObject> parentObject =
+      do_QueryInterface(mMediaSource->GetParentObject());
+  if (!parentObject) {
+    aRv.Throw(NS_ERROR_UNEXPECTED);
+    return nullptr;
+  }
+
+  RefPtr<Promise> promise = Promise::Create(parentObject, aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  PrepareRemove(aStart, aEnd, aRv);
+
+  if (aRv.Failed()) {
+    // The bindings will automatically return a rejected promise.
+    return nullptr;
+  }
+  MOZ_ASSERT(!mDOMPromise, "Can't have a pending operation going");
+  mDOMPromise = promise;
+  RangeRemoval(aStart, aEnd);
+
+  return promise.forget();
+}
+
+void SourceBuffer::PrepareRemove(double aStart, double aEnd, ErrorResult& aRv) {
+  if (!IsAttached()) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+  if (mUpdating) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+  if (IsNaN(mMediaSource->Duration())) {
+    aRv.ThrowTypeError("Duration is NaN");
+    return;
+  }
+  if (aStart < 0 || aStart > mMediaSource->Duration()) {
+    aRv.ThrowTypeError("Invalid start value");
+    return;
+  }
+  if (aEnd <= aStart || IsNaN(aEnd)) {
+    aRv.ThrowTypeError("Invalid end value");
+    return;
+  }
+  if (mMediaSource->ReadyState() == MediaSourceReadyState::Ended) {
+    mMediaSource->SetReadyState(MediaSourceReadyState::Open);
+  }
+}
+
+void SourceBuffer::RangeRemoval(double aStart, double aEnd) {
+  StartUpdating();
+
+  RefPtr<SourceBuffer> self = this;
+  mTrackBuffersManager
+      ->RangeRemoval(TimeUnit::FromSeconds(aStart), TimeUnit::FromSeconds(aEnd))
+      ->Then(
+          mAbstractMainThread, __func__,
+          [self](bool) {
+            self->mPendingRemoval.Complete();
+            self->StopUpdating();
+          },
+          []() { MOZ_ASSERT(false); })
+      ->Track(mPendingRemoval);
+}
+
+void SourceBuffer::ChangeType(const nsAString& aType, ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // 1. If type is an empty string then throw a TypeError exception and abort
+  //    these steps.
+  if (aType.IsEmpty()) {
+    aRv.ThrowTypeError("Type must not be empty");
+    return;
+  }
+
+  // 2. If this object has been removed from the sourceBuffers attribute of the
+  //    parent media source , then throw an InvalidStateError exception and
+  //    abort these steps.
+  // 3. If the updating attribute equals true, then throw an InvalidStateError
+  //    exception and abort these steps.
+  if (!IsAttached() || mUpdating) {
+    DDLOG(DDLogCategory::API, "ChangeType", NS_ERROR_DOM_INVALID_STATE_ERR);
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+
+  // 4. If type contains a MIME type that is not supported or contains a MIME
+  //    type that is not supported with the types specified (currently or
+  //    previously) of SourceBuffer objects in the sourceBuffers attribute of
+  //    the parent media source , then throw a NotSupportedError exception and
+  //    abort these steps.
+  DecoderDoctorDiagnostics diagnostics;
+  MediaSource::IsTypeSupported(aType, &diagnostics, aRv);
+  bool supported = !aRv.Failed();
+  diagnostics.StoreFormatDiagnostics(
+      mMediaSource->GetOwner() ? mMediaSource->GetOwner()->GetExtantDoc()
+                               : nullptr,
+      aType, supported, __func__);
+  MSE_API("ChangeType(aType=%s)%s", NS_ConvertUTF16toUTF8(aType).get(),
+          supported ? "" : " [not supported]");
+  if (!supported) {
+    DDLOG(DDLogCategory::API, "ChangeType",
+          static_cast<nsresult>(aRv.ErrorCodeAsInt()));
+    return;
+  }
+
+  // 5. If the readyState attribute of the parent media source is in the "ended"
+  //    state then run the following steps:
+  //    1. Set the readyState attribute of the parent media source to "open"
+  //    2.   Queue a task to fire a simple event named sourceopen at the parent
+  //         media source .
+  MOZ_ASSERT(mMediaSource->ReadyState() != MediaSourceReadyState::Closed);
+  if (mMediaSource->ReadyState() == MediaSourceReadyState::Ended) {
+    mMediaSource->SetReadyState(MediaSourceReadyState::Open);
+  }
+  Maybe<MediaContainerType> containerType = MakeMediaContainerType(aType);
+  MOZ_ASSERT(containerType);
+  mType = *containerType;
+  // 6. Run the reset parser state algorithm .
+  ResetParserState();
+
+  // 7. Update the generate timestamps flag on this SourceBuffer object to the
+  //    value in the "Generate Timestamps Flag" column of the byte stream format
+  //    registry [ MSE-REGISTRY ] entry that is associated with type .
+  if (mType.Type() == MEDIAMIMETYPE("audio/mpeg") ||
+      mType.Type() == MEDIAMIMETYPE("audio/aac")) {
+    mCurrentAttributes.mGenerateTimestamps = true;
+    // 8. If the generate timestamps flag equals true:
+    //    Set the mode attribute on this SourceBuffer object to "sequence" ,
+    //    including running the associated steps for that attribute being set.
+    ErrorResult dummy;
+    SetMode(SourceBufferAppendMode::Sequence, dummy);
+  } else {
+    mCurrentAttributes.mGenerateTimestamps = false;
+    //    Otherwise: Keep the previous value of the mode attribute on this
+    //    SourceBuffer object, without running any associated steps for that
+    //    attribute being set.
+  }
+
+  // 9. Set pending initialization segment for changeType flag to true.
+  mTrackBuffersManager->ChangeType(mType);
+}
+
+void SourceBuffer::Detach() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_DEBUG("Detach");
+  if (!mMediaSource) {
+    MSE_DEBUG("Already detached");
+    return;
+  }
+  AbortBufferAppend();
+  if (mTrackBuffersManager) {
+    mMediaSource->GetDecoder()->GetDemuxer()->DetachSourceBuffer(
+        mTrackBuffersManager);
+    mTrackBuffersManager->Detach();
+  }
+  mTrackBuffersManager = nullptr;
+  mMediaSource = nullptr;
+}
+
+void SourceBuffer::Ended() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(IsAttached());
+  MSE_DEBUG("Ended");
+  mTrackBuffersManager->Ended();
+}
+
+SourceBuffer::SourceBuffer(MediaSource* aMediaSource,
+                           const MediaContainerType& aType)
+    : DOMEventTargetHelper(aMediaSource->GetParentObject()),
+      mMediaSource(aMediaSource),
+      mAbstractMainThread(aMediaSource->AbstractMainThread()),
+      mCurrentAttributes(aType.Type() == MEDIAMIMETYPE("audio/mpeg") ||
+                         aType.Type() == MEDIAMIMETYPE("audio/aac")),
+      mUpdating(false),
+      mActive(false),
+      mType(aType) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aMediaSource);
+
+  mTrackBuffersManager =
+      new TrackBuffersManager(aMediaSource->GetDecoder(), aType);
+  DDLINKCHILD("track buffers manager", mTrackBuffersManager.get());
+
+  MSE_DEBUG("Create mTrackBuffersManager=%p", mTrackBuffersManager.get());
+
+  ErrorResult dummy;
+  if (mCurrentAttributes.mGenerateTimestamps) {
+    SetMode(SourceBufferAppendMode::Sequence, dummy);
+  } else {
+    SetMode(SourceBufferAppendMode::Segments, dummy);
+  }
+  mMediaSource->GetDecoder()->GetDemuxer()->AttachSourceBuffer(
+      mTrackBuffersManager);
+}
+
+SourceBuffer::~SourceBuffer() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!mMediaSource);
+  MSE_DEBUG("");
+}
+
+MediaSource* SourceBuffer::GetParentObject() const { return mMediaSource; }
+
+JSObject* SourceBuffer::WrapObject(JSContext* aCx,
+                                   JS::Handle<JSObject*> aGivenProto) {
+  return SourceBuffer_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+void SourceBuffer::DispatchSimpleEvent(const char* aName) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_API("Dispatch event '%s'", aName);
+  DispatchTrustedEvent(NS_ConvertUTF8toUTF16(aName));
+}
+
+void SourceBuffer::QueueAsyncSimpleEvent(const char* aName) {
+  MSE_DEBUG("Queuing event '%s'", aName);
+  nsCOMPtr<nsIRunnable> event = new AsyncEventRunner<SourceBuffer>(this, aName);
+  mAbstractMainThread->Dispatch(event.forget());
+}
+
+void SourceBuffer::StartUpdating() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!mUpdating);
+  mUpdating = true;
+  QueueAsyncSimpleEvent("updatestart");
+}
+
+void SourceBuffer::StopUpdating() {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (!mUpdating) {
+    // The buffer append or range removal algorithm  has been interrupted by
+    // abort().
+    return;
+  }
+  mUpdating = false;
+  QueueAsyncSimpleEvent("update");
+  QueueAsyncSimpleEvent("updateend");
+  if (mDOMPromise) {
+    mDOMPromise->MaybeResolveWithUndefined();
+    mDOMPromise = nullptr;
+  }
+}
+
+void SourceBuffer::AbortUpdating() {
+  MOZ_ASSERT(NS_IsMainThread());
+  mUpdating = false;
+  QueueAsyncSimpleEvent("abort");
+  QueueAsyncSimpleEvent("updateend");
+  if (mDOMPromise) {
+    mDOMPromise->MaybeReject(NS_ERROR_DOM_MEDIA_ABORT_ERR);
+    mDOMPromise = nullptr;
+  }
+}
+
+void SourceBuffer::CheckEndTime() {
+  MOZ_ASSERT(NS_IsMainThread());
+  // Check if we need to update mMediaSource duration
+  double endTime = mCurrentAttributes.GetGroupEndTimestamp().ToSeconds();
+  double duration = mMediaSource->Duration();
+  if (endTime > duration) {
+    mMediaSource->SetDuration(endTime);
+  }
+}
+
+void SourceBuffer::AppendData(const uint8_t* aData, uint32_t aLength,
+                              ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_DEBUG("AppendData(aLength=%u)", aLength);
+
+  RefPtr<MediaByteBuffer> data = PrepareAppend(aData, aLength, aRv);
+  if (!data) {
+    return;
+  }
+  StartUpdating();
+
+  mTrackBuffersManager->AppendData(data.forget(), mCurrentAttributes)
+      ->Then(mAbstractMainThread, __func__, this,
+             &SourceBuffer::AppendDataCompletedWithSuccess,
+             &SourceBuffer::AppendDataErrored)
+      ->Track(mPendingAppend);
+}
+
+already_AddRefed<Promise> SourceBuffer::AppendDataAsync(const uint8_t* aData,
+                                                        uint32_t aLength,
+                                                        ErrorResult& aRv) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!IsAttached()) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIGlobalObject> parentObject =
+      do_QueryInterface(mMediaSource->GetParentObject());
+  if (!parentObject) {
+    aRv.Throw(NS_ERROR_UNEXPECTED);
+    return nullptr;
+  }
+
+  RefPtr<Promise> promise = Promise::Create(parentObject, aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  AppendData(aData, aLength, aRv);
+
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  MOZ_ASSERT(!mDOMPromise, "Can't have a pending operation going");
+  mDOMPromise = promise;
+
+  return promise.forget();
+}
+
+void SourceBuffer::AppendDataCompletedWithSuccess(
+    const SourceBufferTask::AppendBufferResult& aResult) {
+  MOZ_ASSERT(mUpdating);
+  mPendingAppend.Complete();
+  DDLOG(DDLogCategory::API, "AppendBuffer-completed", NS_OK);
+
+  if (aResult.first) {
+    if (!mActive) {
+      mActive = true;
+      MSE_DEBUG("Init segment received");
+      RefPtr<SourceBuffer> self = this;
+      mMediaSource->SourceBufferIsActive(this)
+          ->Then(mAbstractMainThread, __func__,
+                 [self, this]() {
+                   MSE_DEBUG("Complete AppendBuffer operation");
+                   mCompletionPromise.Complete();
+                   StopUpdating();
+                 })
+          ->Track(mCompletionPromise);
+    }
+  }
+  if (mActive) {
+    // Tell our parent decoder that we have received new data
+    // and send progress event.
+    mMediaSource->GetDecoder()->NotifyDataArrived();
+  }
+
+  mCurrentAttributes = aResult.second;
+
+  CheckEndTime();
+
+  if (!mCompletionPromise.Exists()) {
+    StopUpdating();
+  }
+}
+
+void SourceBuffer::AppendDataErrored(const MediaResult& aError) {
+  MOZ_ASSERT(mUpdating);
+  mPendingAppend.Complete();
+  DDLOG(DDLogCategory::API, "AppendBuffer-error", aError);
+
+  switch (aError.Code()) {
+    case NS_ERROR_DOM_MEDIA_CANCELED:
+      // Nothing further to do as the trackbuffer has been shutdown.
+      // or append was aborted and abort() has handled all the events.
+      break;
+    default:
+      AppendError(aError);
+      break;
+  }
+}
+
+void SourceBuffer::AppendError(const MediaResult& aDecodeError) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  ResetParserState();
+
+  mUpdating = false;
+
+  QueueAsyncSimpleEvent("error");
+  QueueAsyncSimpleEvent("updateend");
+
+  MOZ_ASSERT(NS_FAILED(aDecodeError));
+
+  mMediaSource->EndOfStream(aDecodeError);
+
+  if (mDOMPromise) {
+    mDOMPromise->MaybeReject(aDecodeError);
+    mDOMPromise = nullptr;
+  }
+}
+
+already_AddRefed<MediaByteBuffer> SourceBuffer::PrepareAppend(
+    const uint8_t* aData, uint32_t aLength, ErrorResult& aRv) {
+  typedef TrackBuffersManager::EvictDataResult Result;
+
+  if (!IsAttached() || mUpdating) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return nullptr;
+  }
+
+  // If the HTMLMediaElement.error attribute is not null, then throw an
+  // InvalidStateError exception and abort these steps.
+  if (!mMediaSource->GetDecoder() ||
+      mMediaSource->GetDecoder()->OwnerHasError()) {
+    MSE_DEBUG("HTMLMediaElement.error is not null");
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return nullptr;
+  }
+
+  if (mMediaSource->ReadyState() == MediaSourceReadyState::Ended) {
+    mMediaSource->SetReadyState(MediaSourceReadyState::Open);
+  }
+
+  // Eviction uses a byte threshold. If the buffer is greater than the
+  // number of bytes then data is evicted.
+  // TODO: Drive evictions off memory pressure notifications.
+  // TODO: Consider a global eviction threshold  rather than per TrackBuffer.
+  // Give a chance to the TrackBuffersManager to evict some data if needed.
+  Result evicted = mTrackBuffersManager->EvictData(
+      TimeUnit::FromSeconds(mMediaSource->GetDecoder()->GetCurrentTime()),
+      aLength);
+
+  // See if we have enough free space to append our new data.
+  if (evicted == Result::BUFFER_FULL) {
+    aRv.Throw(NS_ERROR_DOM_QUOTA_EXCEEDED_ERR);
+    return nullptr;
+  }
+
+  RefPtr<MediaByteBuffer> data = new MediaByteBuffer();
+  if (!data->AppendElements(aData, aLength, fallible)) {
+    aRv.Throw(NS_ERROR_DOM_QUOTA_EXCEEDED_ERR);
+    return nullptr;
+  }
+  return data.forget();
+}
+
+double SourceBuffer::GetBufferedStart() {
+  MOZ_ASSERT(NS_IsMainThread());
+  ErrorResult dummy;
+  RefPtr<TimeRanges> ranges = GetBuffered(dummy);
+  return ranges->Length() > 0 ? ranges->GetStartTime() : 0;
+}
+
+double SourceBuffer::GetBufferedEnd() {
+  MOZ_ASSERT(NS_IsMainThread());
+  ErrorResult dummy;
+  RefPtr<TimeRanges> ranges = GetBuffered(dummy);
+  return ranges->Length() > 0 ? ranges->GetEndTime() : 0;
+}
+
+double SourceBuffer::HighestStartTime() {
+  MOZ_ASSERT(NS_IsMainThread());
+  return mTrackBuffersManager
+             ? mTrackBuffersManager->HighestStartTime().ToSeconds()
+             : 0.0;
+}
+
+double SourceBuffer::HighestEndTime() {
+  MOZ_ASSERT(NS_IsMainThread());
+  return mTrackBuffersManager
+             ? mTrackBuffersManager->HighestEndTime().ToSeconds()
+             : 0.0;
+}
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(SourceBuffer)
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(SourceBuffer)
+  tmp->Detach();
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mMediaSource)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mBuffered)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mDOMPromise)
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END_INHERITED(DOMEventTargetHelper)
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(SourceBuffer,
+                                                  DOMEventTargetHelper)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mMediaSource)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mBuffered)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mDOMPromise)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_ADDREF_INHERITED(SourceBuffer, DOMEventTargetHelper)
+NS_IMPL_RELEASE_INHERITED(SourceBuffer, DOMEventTargetHelper)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(SourceBuffer)
+NS_INTERFACE_MAP_END_INHERITING(DOMEventTargetHelper)
+
+#undef MSE_DEBUG
+#undef MSE_DEBUGV
+#undef MSE_API
+
+}  // namespace dom
+
+}  // namespace mozilla
diff --git a/dom/media/mediasource/SourceBuffer.h b/dom/media/mediasource/SourceBuffer.h
new file mode 100644
index 0000000000..783d4a0a07
--- /dev/null
+++ b/dom/media/mediasource/SourceBuffer.h
@@ -0,0 +1,207 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_SourceBuffer_h_
+#define mozilla_dom_SourceBuffer_h_
+
+#include "mozilla/MozPromise.h"
+#include "MediaContainerType.h"
+#include "MediaSource.h"
+#include "js/RootingAPI.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/DOMEventTargetHelper.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/dom/SourceBufferBinding.h"
+#include "mozilla/dom/TypedArray.h"
+#include "mozilla/mozalloc.h"
+#include "nsCOMPtr.h"
+#include "nsCycleCollectionNoteChild.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsISupports.h"
+#include "nscore.h"
+#include "TrackBuffersManager.h"
+#include "SourceBufferTask.h"
+
+class JSObject;
+struct JSContext;
+
+namespace mozilla {
+
+class AbstractThread;
+class ErrorResult;
+class MediaByteBuffer;
+template <typename T>
+class AsyncEventRunner;
+
+DDLoggedTypeName(dom::SourceBuffer);
+
+namespace dom {
+
+class TimeRanges;
+
+class SourceBuffer final : public DOMEventTargetHelper,
+                           public DecoderDoctorLifeLogger<SourceBuffer> {
+ public:
+  /** WebIDL Methods. */
+  SourceBufferAppendMode Mode() const {
+    return mCurrentAttributes.GetAppendMode();
+  }
+
+  void SetMode(SourceBufferAppendMode aMode, ErrorResult& aRv);
+
+  bool Updating() const { return mUpdating; }
+
+  TimeRanges* GetBuffered(ErrorResult& aRv);
+  media::TimeIntervals GetTimeIntervals();
+
+  double TimestampOffset() const {
+    return mCurrentAttributes.GetApparentTimestampOffset();
+  }
+
+  void SetTimestampOffset(double aTimestampOffset, ErrorResult& aRv);
+
+  double AppendWindowStart() const {
+    return mCurrentAttributes.GetAppendWindowStart();
+  }
+
+  void SetAppendWindowStart(double aAppendWindowStart, ErrorResult& aRv);
+
+  double AppendWindowEnd() const {
+    return mCurrentAttributes.GetAppendWindowEnd();
+  }
+
+  void SetAppendWindowEnd(double aAppendWindowEnd, ErrorResult& aRv);
+
+  void AppendBuffer(const ArrayBuffer& aData, ErrorResult& aRv);
+  void AppendBuffer(const ArrayBufferView& aData, ErrorResult& aRv);
+
+  already_AddRefed<Promise> AppendBufferAsync(const ArrayBuffer& aData,
+                                              ErrorResult& aRv);
+  already_AddRefed<Promise> AppendBufferAsync(const ArrayBufferView& aData,
+                                              ErrorResult& aRv);
+
+  void Abort(ErrorResult& aRv);
+  void AbortBufferAppend();
+
+  void Remove(double aStart, double aEnd, ErrorResult& aRv);
+
+  already_AddRefed<Promise> RemoveAsync(double aStart, double aEnd,
+                                        ErrorResult& aRv);
+
+  void ChangeType(const nsAString& aType, ErrorResult& aRv);
+
+  IMPL_EVENT_HANDLER(updatestart);
+  IMPL_EVENT_HANDLER(update);
+  IMPL_EVENT_HANDLER(updateend);
+  IMPL_EVENT_HANDLER(error);
+  IMPL_EVENT_HANDLER(abort);
+
+  /** End WebIDL Methods. */
+
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(SourceBuffer, DOMEventTargetHelper)
+
+  SourceBuffer(MediaSource* aMediaSource, const MediaContainerType& aType);
+
+  MediaSource* GetParentObject() const;
+
+  JSObject* WrapObject(JSContext* aCx,
+                       JS::Handle<JSObject*> aGivenProto) override;
+
+  // Notify the SourceBuffer that it has been detached from the
+  // MediaSource's sourceBuffer list.
+  void Detach();
+  bool IsAttached() const { return mMediaSource != nullptr; }
+
+  void Ended();
+
+  double GetBufferedStart();
+  double GetBufferedEnd();
+  double HighestStartTime();
+  double HighestEndTime();
+
+  // Runs the range removal algorithm as defined by the MSE spec.
+  void RangeRemoval(double aStart, double aEnd);
+
+  bool IsActive() const { return mActive; }
+
+ private:
+  ~SourceBuffer();
+
+  friend class AsyncEventRunner<SourceBuffer>;
+  friend class BufferAppendRunnable;
+  friend class mozilla::TrackBuffersManager;
+  void DispatchSimpleEvent(const char* aName);
+  void QueueAsyncSimpleEvent(const char* aName);
+
+  // Update mUpdating and fire the appropriate events.
+  void StartUpdating();
+  void StopUpdating();
+  void AbortUpdating();
+  void ResetParserState();
+
+  // If the media segment contains data beyond the current duration,
+  // then run the duration change algorithm with new duration set to the
+  // maximum of the current duration and the group end timestamp.
+  void CheckEndTime();
+
+  // Shared implementation of AppendBuffer overloads.
+  void AppendData(const uint8_t* aData, uint32_t aLength, ErrorResult& aRv);
+  // Shared implementation of AppendBufferAsync overloads.
+  already_AddRefed<Promise> AppendDataAsync(const uint8_t* aData,
+                                            uint32_t aLength, ErrorResult& aRv);
+
+  void PrepareRemove(double aStart, double aEnd, ErrorResult& aRv);
+
+  // Implement the "Append Error Algorithm".
+  // Will call endOfStream() with "decode" error if aDecodeError is true.
+  // 3.5.3 Append Error Algorithm
+  // http://w3c.github.io/media-source/#sourcebuffer-append-error
+  void AppendError(const MediaResult& aDecodeError);
+
+  // Implements the "Prepare Append Algorithm". Returns MediaByteBuffer object
+  // on success or nullptr (with aRv set) on error.
+  already_AddRefed<MediaByteBuffer> PrepareAppend(const uint8_t* aData,
+                                                  uint32_t aLength,
+                                                  ErrorResult& aRv);
+
+  void AppendDataCompletedWithSuccess(
+      const SourceBufferTask::AppendBufferResult& aResult);
+  void AppendDataErrored(const MediaResult& aError);
+
+  RefPtr<MediaSource> mMediaSource;
+  const RefPtr<AbstractThread> mAbstractMainThread;
+
+  RefPtr<TrackBuffersManager> mTrackBuffersManager;
+  SourceBufferAttributes mCurrentAttributes;
+
+  bool mUpdating;
+
+  mozilla::Atomic<bool> mActive;
+
+  MozPromiseRequestHolder<SourceBufferTask::AppendPromise> mPendingAppend;
+  MozPromiseRequestHolder<SourceBufferTask::RangeRemovalPromise>
+      mPendingRemoval;
+  MediaContainerType mType;
+
+  RefPtr<TimeRanges> mBuffered;
+
+  MozPromiseRequestHolder<MediaSource::ActiveCompletionPromise>
+      mCompletionPromise;
+
+  // Only used if MSE v2 experimental mode is active.
+  // Contains the current Promise to be resolved following use of
+  // appendBufferAsync and removeAsync. Not set of no operation is pending.
+  RefPtr<Promise> mDOMPromise;
+};
+
+}  // namespace dom
+
+}  // namespace mozilla
+
+#endif /* mozilla_dom_SourceBuffer_h_ */
diff --git a/dom/media/mediasource/SourceBufferAttributes.h b/dom/media/mediasource/SourceBufferAttributes.h
new file mode 100644
index 0000000000..f15845b8a9
--- /dev/null
+++ b/dom/media/mediasource/SourceBufferAttributes.h
@@ -0,0 +1,116 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_SourceBufferAttributes_h_
+#define mozilla_SourceBufferAttributes_h_
+
+#include "TimeUnits.h"
+#include "mozilla/dom/SourceBufferBinding.h"
+#include "mozilla/Maybe.h"
+
+namespace mozilla {
+
+class SourceBufferAttributes {
+ public:
+  // Current state as per Segment Parser Loop Algorithm
+  // http://w3c.github.io/media-source/index.html#sourcebuffer-segment-parser-loop
+  enum class AppendState {
+    WAITING_FOR_SEGMENT,
+    PARSING_INIT_SEGMENT,
+    PARSING_MEDIA_SEGMENT,
+  };
+
+  explicit SourceBufferAttributes(bool aGenerateTimestamp)
+      : mGenerateTimestamps(aGenerateTimestamp),
+        mAppendWindowStart(0),
+        mAppendWindowEnd(PositiveInfinity<double>()),
+        mAppendMode(dom::SourceBufferAppendMode::Segments),
+        mApparentTimestampOffset(0),
+        mAppendState(AppendState::WAITING_FOR_SEGMENT) {}
+
+  SourceBufferAttributes(const SourceBufferAttributes& aOther) = default;
+
+  double GetAppendWindowStart() const { return mAppendWindowStart; }
+
+  double GetAppendWindowEnd() const { return mAppendWindowEnd; }
+
+  void SetAppendWindowStart(double aWindowStart) {
+    mAppendWindowStart = aWindowStart;
+  }
+
+  void SetAppendWindowEnd(double aWindowEnd) { mAppendWindowEnd = aWindowEnd; }
+
+  double GetApparentTimestampOffset() const { return mApparentTimestampOffset; }
+
+  void SetApparentTimestampOffset(double aTimestampOffset) {
+    mApparentTimestampOffset = aTimestampOffset;
+    mTimestampOffset = media::TimeUnit::FromSeconds(aTimestampOffset);
+  }
+
+  media::TimeUnit GetTimestampOffset() const { return mTimestampOffset; }
+
+  void SetTimestampOffset(const media::TimeUnit& aTimestampOffset) {
+    mTimestampOffset = aTimestampOffset;
+    mApparentTimestampOffset = aTimestampOffset.ToSeconds();
+  }
+
+  dom::SourceBufferAppendMode GetAppendMode() const { return mAppendMode; }
+
+  void SetAppendMode(dom::SourceBufferAppendMode aAppendMode) {
+    mAppendMode = aAppendMode;
+  }
+
+  void SetGroupStartTimestamp(const media::TimeUnit& aGroupStartTimestamp) {
+    mGroupStartTimestamp = Some(aGroupStartTimestamp);
+  }
+
+  media::TimeUnit GetGroupStartTimestamp() const {
+    return mGroupStartTimestamp.ref();
+  }
+
+  bool HaveGroupStartTimestamp() const { return mGroupStartTimestamp.isSome(); }
+
+  void ResetGroupStartTimestamp() { mGroupStartTimestamp.reset(); }
+
+  void RestartGroupStartTimestamp() {
+    mGroupStartTimestamp = Some(mGroupEndTimestamp);
+  }
+
+  media::TimeUnit GetGroupEndTimestamp() const { return mGroupEndTimestamp; }
+
+  void SetGroupEndTimestamp(const media::TimeUnit& aGroupEndTimestamp) {
+    mGroupEndTimestamp = aGroupEndTimestamp;
+  }
+
+  AppendState GetAppendState() const { return mAppendState; }
+
+  void SetAppendState(AppendState aState) { mAppendState = aState; }
+
+  // mGenerateTimestamp isn't mutable once the source buffer has been
+  // constructed
+  bool mGenerateTimestamps;
+
+  SourceBufferAttributes& operator=(const SourceBufferAttributes& aOther) =
+      default;
+
+ private:
+  SourceBufferAttributes() = delete;
+
+  double mAppendWindowStart;
+  double mAppendWindowEnd;
+  dom::SourceBufferAppendMode mAppendMode;
+  double mApparentTimestampOffset;
+  media::TimeUnit mTimestampOffset;
+  Maybe<media::TimeUnit> mGroupStartTimestamp;
+  media::TimeUnit mGroupEndTimestamp;
+  // The current append state as per
+  // https://w3c.github.io/media-source/#sourcebuffer-append-state
+  AppendState mAppendState;
+};
+
+}  // end namespace mozilla
+
+#endif /* mozilla_SourceBufferAttributes_h_ */
diff --git a/dom/media/mediasource/SourceBufferList.cpp b/dom/media/mediasource/SourceBufferList.cpp
new file mode 100644
index 0000000000..fe5d27a7da
--- /dev/null
+++ b/dom/media/mediasource/SourceBufferList.cpp
@@ -0,0 +1,185 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "SourceBufferList.h"
+
+#include "AsyncEventRunner.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/dom/SourceBufferListBinding.h"
+#include "mozilla/mozalloc.h"
+#include "nsCOMPtr.h"
+#include "nsIRunnable.h"
+#include "nsString.h"
+#include "nsThreadUtils.h"
+#include "mozilla/Logging.h"
+
+extern mozilla::LogModule* GetMediaSourceLog();
+extern mozilla::LogModule* GetMediaSourceAPILog();
+
+#define MSE_API(arg, ...)                                   \
+  MOZ_LOG(GetMediaSourceAPILog(), mozilla::LogLevel::Debug, \
+          ("SourceBufferList(%p)::%s: " arg, this, __func__, ##__VA_ARGS__))
+#define MSE_DEBUG(arg, ...)                              \
+  MOZ_LOG(GetMediaSourceLog(), mozilla::LogLevel::Debug, \
+          ("SourceBufferList(%p)::%s: " arg, this, __func__, ##__VA_ARGS__))
+
+struct JSContext;
+class JSObject;
+
+namespace mozilla::dom {
+
+SourceBufferList::~SourceBufferList() = default;
+
+SourceBuffer* SourceBufferList::IndexedGetter(uint32_t aIndex, bool& aFound) {
+  MOZ_ASSERT(NS_IsMainThread());
+  aFound = aIndex < mSourceBuffers.Length();
+
+  if (!aFound) {
+    return nullptr;
+  }
+  return mSourceBuffers[aIndex];
+}
+
+uint32_t SourceBufferList::Length() {
+  MOZ_ASSERT(NS_IsMainThread());
+  return mSourceBuffers.Length();
+}
+
+void SourceBufferList::Append(SourceBuffer* aSourceBuffer) {
+  MOZ_ASSERT(NS_IsMainThread());
+  mSourceBuffers.AppendElement(aSourceBuffer);
+  QueueAsyncSimpleEvent("addsourcebuffer");
+}
+
+void SourceBufferList::AppendSimple(SourceBuffer* aSourceBuffer) {
+  MOZ_ASSERT(NS_IsMainThread());
+  mSourceBuffers.AppendElement(aSourceBuffer);
+}
+
+void SourceBufferList::Remove(SourceBuffer* aSourceBuffer) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ALWAYS_TRUE(mSourceBuffers.RemoveElement(aSourceBuffer));
+  aSourceBuffer->Detach();
+  QueueAsyncSimpleEvent("removesourcebuffer");
+}
+
+bool SourceBufferList::Contains(SourceBuffer* aSourceBuffer) {
+  MOZ_ASSERT(NS_IsMainThread());
+  return mSourceBuffers.Contains(aSourceBuffer);
+}
+
+void SourceBufferList::Clear() {
+  MOZ_ASSERT(NS_IsMainThread());
+  for (uint32_t i = 0; i < mSourceBuffers.Length(); ++i) {
+    mSourceBuffers[i]->Detach();
+  }
+  mSourceBuffers.Clear();
+  QueueAsyncSimpleEvent("removesourcebuffer");
+}
+
+void SourceBufferList::ClearSimple() {
+  MOZ_ASSERT(NS_IsMainThread());
+  mSourceBuffers.Clear();
+}
+
+bool SourceBufferList::IsEmpty() {
+  MOZ_ASSERT(NS_IsMainThread());
+  return mSourceBuffers.IsEmpty();
+}
+
+bool SourceBufferList::AnyUpdating() {
+  MOZ_ASSERT(NS_IsMainThread());
+  for (uint32_t i = 0; i < mSourceBuffers.Length(); ++i) {
+    if (mSourceBuffers[i]->Updating()) {
+      return true;
+    }
+  }
+  return false;
+}
+
+void SourceBufferList::RangeRemoval(double aStart, double aEnd) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_DEBUG("RangeRemoval(aStart=%f, aEnd=%f)", aStart, aEnd);
+  for (uint32_t i = 0; i < mSourceBuffers.Length(); ++i) {
+    mSourceBuffers[i]->RangeRemoval(aStart, aEnd);
+  }
+}
+
+void SourceBufferList::Ended() {
+  MOZ_ASSERT(NS_IsMainThread());
+  for (uint32_t i = 0; i < mSourceBuffers.Length(); ++i) {
+    mSourceBuffers[i]->Ended();
+  }
+}
+
+double SourceBufferList::GetHighestBufferedEndTime() {
+  MOZ_ASSERT(NS_IsMainThread());
+  double highestEndTime = 0;
+  for (uint32_t i = 0; i < mSourceBuffers.Length(); ++i) {
+    highestEndTime =
+        std::max(highestEndTime, mSourceBuffers[i]->GetBufferedEnd());
+  }
+  return highestEndTime;
+}
+
+void SourceBufferList::DispatchSimpleEvent(const char* aName) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_API("Dispatch event '%s'", aName);
+  DispatchTrustedEvent(NS_ConvertUTF8toUTF16(aName));
+}
+
+void SourceBufferList::QueueAsyncSimpleEvent(const char* aName) {
+  MSE_DEBUG("Queue event '%s'", aName);
+  nsCOMPtr<nsIRunnable> event =
+      new AsyncEventRunner<SourceBufferList>(this, aName);
+  mAbstractMainThread->Dispatch(event.forget());
+}
+
+SourceBufferList::SourceBufferList(MediaSource* aMediaSource)
+    : DOMEventTargetHelper(aMediaSource->GetParentObject()),
+      mMediaSource(aMediaSource),
+      mAbstractMainThread(mMediaSource->AbstractMainThread()) {
+  MOZ_ASSERT(aMediaSource);
+}
+
+MediaSource* SourceBufferList::GetParentObject() const { return mMediaSource; }
+
+double SourceBufferList::HighestStartTime() {
+  MOZ_ASSERT(NS_IsMainThread());
+  double highestStartTime = 0;
+  for (auto& sourceBuffer : mSourceBuffers) {
+    highestStartTime =
+        std::max(sourceBuffer->HighestStartTime(), highestStartTime);
+  }
+  return highestStartTime;
+}
+
+double SourceBufferList::HighestEndTime() {
+  MOZ_ASSERT(NS_IsMainThread());
+  double highestEndTime = 0;
+  for (auto& sourceBuffer : mSourceBuffers) {
+    highestEndTime = std::max(sourceBuffer->HighestEndTime(), highestEndTime);
+  }
+  return highestEndTime;
+}
+
+JSObject* SourceBufferList::WrapObject(JSContext* aCx,
+                                       JS::Handle<JSObject*> aGivenProto) {
+  return SourceBufferList_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+NS_IMPL_CYCLE_COLLECTION_INHERITED(SourceBufferList, DOMEventTargetHelper,
+                                   mMediaSource, mSourceBuffers)
+
+NS_IMPL_ADDREF_INHERITED(SourceBufferList, DOMEventTargetHelper)
+NS_IMPL_RELEASE_INHERITED(SourceBufferList, DOMEventTargetHelper)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(SourceBufferList)
+NS_INTERFACE_MAP_END_INHERITING(DOMEventTargetHelper)
+
+#undef MSE_API
+#undef MSE_DEBUG
+}  // namespace mozilla::dom
diff --git a/dom/media/mediasource/SourceBufferList.h b/dom/media/mediasource/SourceBufferList.h
new file mode 100644
index 0000000000..43571ac00a
--- /dev/null
+++ b/dom/media/mediasource/SourceBufferList.h
@@ -0,0 +1,110 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_SourceBufferList_h_
+#define mozilla_dom_SourceBufferList_h_
+
+#include "SourceBuffer.h"
+#include "js/RootingAPI.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/DOMEventTargetHelper.h"
+#include "nsCycleCollectionNoteChild.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsISupports.h"
+#include "nsTArray.h"
+
+struct JSContext;
+class JSObject;
+
+namespace mozilla {
+
+template <typename T>
+class AsyncEventRunner;
+
+namespace dom {
+
+class MediaSource;
+
+class SourceBufferList final : public DOMEventTargetHelper {
+ public:
+  /** WebIDL Methods. */
+  SourceBuffer* IndexedGetter(uint32_t aIndex, bool& aFound);
+
+  uint32_t Length();
+
+  IMPL_EVENT_HANDLER(addsourcebuffer);
+  IMPL_EVENT_HANDLER(removesourcebuffer);
+
+  /** End WebIDL methods. */
+
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(SourceBufferList,
+                                           DOMEventTargetHelper)
+
+  explicit SourceBufferList(MediaSource* aMediaSource);
+
+  MediaSource* GetParentObject() const;
+
+  JSObject* WrapObject(JSContext* aCx,
+                       JS::Handle<JSObject*> aGivenProto) override;
+
+  // Append a SourceBuffer and fire "addsourcebuffer" at the list.
+  void Append(SourceBuffer* aSourceBuffer);
+
+  // Remove a SourceBuffer and fire "removesourcebuffer" at the list.
+  void Remove(SourceBuffer* aSourceBuffer);
+
+  // Returns true if aSourceBuffer is present in the list.
+  bool Contains(SourceBuffer* aSourceBuffer);
+
+  // Remove all SourceBuffers and fire a single "removesourcebuffer" at the
+  // list.
+  void Clear();
+
+  // True if list has zero entries.
+  bool IsEmpty();
+
+  // Returns true if updating is true on any SourceBuffers in the list.
+  bool AnyUpdating();
+
+  // Runs the range removal steps from the MSE specification on each
+  // SourceBuffer.
+  void RangeRemoval(double aStart, double aEnd);
+
+  // Mark all SourceBuffers input buffers as ended.
+  void Ended();
+
+  // Returns the highest end time of any of the Sourcebuffers.
+  double GetHighestBufferedEndTime();
+
+  // Append a SourceBuffer to the list. No event is fired.
+  void AppendSimple(SourceBuffer* aSourceBuffer);
+
+  // Remove all SourceBuffers from mSourceBuffers.
+  //  No event is fired and no action is performed on the sourcebuffers.
+  void ClearSimple();
+
+  double HighestStartTime();
+  double HighestEndTime();
+
+ private:
+  ~SourceBufferList();
+
+  friend class AsyncEventRunner<SourceBufferList>;
+  void DispatchSimpleEvent(const char* aName);
+  void QueueAsyncSimpleEvent(const char* aName);
+
+  RefPtr<MediaSource> mMediaSource;
+  nsTArray<RefPtr<SourceBuffer> > mSourceBuffers;
+  const RefPtr<AbstractThread> mAbstractMainThread;
+};
+
+}  // namespace dom
+
+}  // namespace mozilla
+
+#endif /* mozilla_dom_SourceBufferList_h_ */
diff --git a/dom/media/mediasource/SourceBufferResource.cpp b/dom/media/mediasource/SourceBufferResource.cpp
new file mode 100644
index 0000000000..49447be015
--- /dev/null
+++ b/dom/media/mediasource/SourceBufferResource.cpp
@@ -0,0 +1,144 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "SourceBufferResource.h"
+
+#include "mozilla/Logging.h"
+#include "mozilla/TaskQueue.h"
+#include "MediaData.h"
+
+mozilla::LogModule* GetSourceBufferResourceLog() {
+  static mozilla::LazyLogModule sLogModule("SourceBufferResource");
+  return sLogModule;
+}
+
+#define SBR_DEBUG(arg, ...)                                         \
+  DDMOZ_LOG(GetSourceBufferResourceLog(), mozilla::LogLevel::Debug, \
+            "::%s: " arg, __func__, ##__VA_ARGS__)
+#define SBR_DEBUGV(arg, ...)                                          \
+  DDMOZ_LOG(GetSourceBufferResourceLog(), mozilla::LogLevel::Verbose, \
+            "::%s: " arg, __func__, ##__VA_ARGS__)
+
+namespace mozilla {
+
+RefPtr<GenericPromise> SourceBufferResource::Close() {
+  MOZ_ASSERT(OnThread());
+  SBR_DEBUG("Close");
+  mClosed = true;
+  return GenericPromise::CreateAndResolve(true, __func__);
+}
+
+nsresult SourceBufferResource::ReadAt(int64_t aOffset, char* aBuffer,
+                                      uint32_t aCount, uint32_t* aBytes) {
+  SBR_DEBUG("ReadAt(aOffset=%" PRId64 ", aBuffer=%p, aCount=%u, aBytes=%p)",
+            aOffset, aBytes, aCount, aBytes);
+  return ReadAtInternal(aOffset, aBuffer, aCount, aBytes);
+}
+
+nsresult SourceBufferResource::ReadAtInternal(int64_t aOffset, char* aBuffer,
+                                              uint32_t aCount,
+                                              uint32_t* aBytes) {
+  MOZ_ASSERT(OnThread());
+
+  if (mClosed || aOffset < 0 || uint64_t(aOffset) < mInputBuffer.GetOffset() ||
+      aOffset > GetLength()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  uint32_t available = GetLength() - aOffset;
+  uint32_t count = std::min(aCount, available);
+
+  SBR_DEBUGV("offset=%" PRId64 " GetLength()=%" PRId64
+             " available=%u count=%u mEnded=%d",
+             aOffset, GetLength(), available, count, mEnded);
+  if (available == 0) {
+    SBR_DEBUGV("reached EOF");
+    *aBytes = 0;
+    return NS_OK;
+  }
+
+  mInputBuffer.CopyData(aOffset, count, aBuffer);
+  *aBytes = count;
+
+  return NS_OK;
+}
+
+nsresult SourceBufferResource::ReadFromCache(char* aBuffer, int64_t aOffset,
+                                             uint32_t aCount) {
+  SBR_DEBUG("ReadFromCache(aBuffer=%p, aOffset=%" PRId64 ", aCount=%u)",
+            aBuffer, aOffset, aCount);
+  uint32_t bytesRead;
+  nsresult rv = ReadAtInternal(aOffset, aBuffer, aCount, &bytesRead);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // ReadFromCache return failure if not all the data is cached.
+  return bytesRead == aCount ? NS_OK : NS_ERROR_FAILURE;
+}
+
+uint32_t SourceBufferResource::EvictData(uint64_t aPlaybackOffset,
+                                         int64_t aThreshold) {
+  MOZ_ASSERT(OnThread());
+  SBR_DEBUG("EvictData(aPlaybackOffset=%" PRIu64
+            ","
+            "aThreshold=%" PRId64 ")",
+            aPlaybackOffset, aThreshold);
+  uint32_t result = mInputBuffer.Evict(aPlaybackOffset, aThreshold);
+  return result;
+}
+
+void SourceBufferResource::EvictBefore(uint64_t aOffset) {
+  MOZ_ASSERT(OnThread());
+  SBR_DEBUG("EvictBefore(aOffset=%" PRIu64 ")", aOffset);
+
+  mInputBuffer.EvictBefore(aOffset);
+}
+
+uint32_t SourceBufferResource::EvictAll() {
+  MOZ_ASSERT(OnThread());
+  SBR_DEBUG("EvictAll()");
+  return mInputBuffer.EvictAll();
+}
+
+void SourceBufferResource::AppendData(MediaByteBuffer* aData) {
+  AppendData(MediaSpan(aData));
+}
+
+void SourceBufferResource::AppendData(const MediaSpan& aData) {
+  MOZ_ASSERT(OnThread());
+  SBR_DEBUG("AppendData(aData=%p, aLength=%zu)", aData.Elements(),
+            aData.Length());
+  mInputBuffer.AppendItem(aData);
+  mEnded = false;
+}
+
+void SourceBufferResource::Ended() {
+  MOZ_ASSERT(OnThread());
+  SBR_DEBUG("");
+  mEnded = true;
+}
+
+SourceBufferResource::~SourceBufferResource() { SBR_DEBUG(""); }
+
+SourceBufferResource::SourceBufferResource()
+#if defined(DEBUG)
+    : mThread(AbstractThread::GetCurrent())
+#endif
+{
+  SBR_DEBUG("");
+}
+
+#if defined(DEBUG)
+const AbstractThread* SourceBufferResource::GetThread() const {
+  return mThread;
+}
+bool SourceBufferResource::OnThread() const {
+  return !GetThread() || GetThread()->IsCurrentThreadIn();
+}
+#endif
+
+#undef SBR_DEBUG
+#undef SBR_DEBUGV
+}  // namespace mozilla
diff --git a/dom/media/mediasource/SourceBufferResource.h b/dom/media/mediasource/SourceBufferResource.h
new file mode 100644
index 0000000000..b117edb558
--- /dev/null
+++ b/dom/media/mediasource/SourceBufferResource.h
@@ -0,0 +1,143 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_SOURCEBUFFERRESOURCE_H_
+#define MOZILLA_SOURCEBUFFERRESOURCE_H_
+
+#include "mozilla/AbstractThread.h"
+#include "mozilla/Logging.h"
+#include "MediaResource.h"
+#include "ResourceQueue.h"
+
+#define UNIMPLEMENTED()                               \
+  { /* Logging this is too spammy to do by default */ \
+  }
+
+namespace mozilla {
+
+class MediaByteBuffer;
+class AbstractThread;
+
+namespace dom {
+
+class SourceBuffer;
+
+}  // namespace dom
+
+DDLoggedTypeDeclNameAndBase(SourceBufferResource, MediaResource);
+
+// SourceBufferResource is not thread safe.
+class SourceBufferResource final
+    : public MediaResource,
+      public DecoderDoctorLifeLogger<SourceBufferResource> {
+ public:
+  SourceBufferResource();
+  RefPtr<GenericPromise> Close() override;
+  nsresult ReadAt(int64_t aOffset, char* aBuffer, uint32_t aCount,
+                  uint32_t* aBytes) override;
+  // Memory-based and no locks, caching discouraged.
+  bool ShouldCacheReads() override { return false; }
+  void Pin() override { UNIMPLEMENTED(); }
+  void Unpin() override { UNIMPLEMENTED(); }
+  int64_t GetLength() override { return mInputBuffer.GetLength(); }
+  int64_t GetNextCachedData(int64_t aOffset) override {
+    MOZ_ASSERT(OnThread());
+    MOZ_ASSERT(aOffset >= 0);
+    if (uint64_t(aOffset) < mInputBuffer.GetOffset()) {
+      return mInputBuffer.GetOffset();
+    } else if (aOffset == GetLength()) {
+      return -1;
+    }
+    return aOffset;
+  }
+  int64_t GetCachedDataEnd(int64_t aOffset) override {
+    MOZ_ASSERT(OnThread());
+    MOZ_ASSERT(aOffset >= 0);
+    if (uint64_t(aOffset) < mInputBuffer.GetOffset() ||
+        aOffset >= GetLength()) {
+      // aOffset is outside of the buffered range.
+      return aOffset;
+    }
+    return GetLength();
+  }
+  bool IsDataCachedToEndOfResource(int64_t aOffset) override { return false; }
+  nsresult ReadFromCache(char* aBuffer, int64_t aOffset,
+                         uint32_t aCount) override;
+
+  nsresult GetCachedRanges(MediaByteRangeSet& aRanges) override {
+    MOZ_ASSERT(OnThread());
+    if (mInputBuffer.GetLength()) {
+      aRanges +=
+          MediaByteRange(mInputBuffer.GetOffset(), mInputBuffer.GetLength());
+    }
+    return NS_OK;
+  }
+
+  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const {
+    MOZ_ASSERT(OnThread());
+    return mInputBuffer.SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  // Used by SourceBuffer.
+  void AppendData(MediaByteBuffer* aData);
+  void AppendData(const MediaSpan& aData);
+  void Ended();
+  bool IsEnded() {
+    MOZ_ASSERT(OnThread());
+    return mEnded;
+  }
+  // Remove data from resource if it holds more than the threshold reduced by
+  // the given number of bytes. Returns amount evicted.
+  uint32_t EvictData(uint64_t aPlaybackOffset, int64_t aThresholdReduct);
+
+  // Remove data from resource before the given offset.
+  void EvictBefore(uint64_t aOffset);
+
+  // Remove all data from the resource
+  uint32_t EvictAll();
+
+  // Returns the amount of data currently retained by this resource.
+  int64_t GetSize() {
+    MOZ_ASSERT(OnThread());
+    return mInputBuffer.GetLength() - mInputBuffer.GetOffset();
+  }
+
+  const uint8_t* GetContiguousAccess(int64_t aOffset, size_t aSize) {
+    return mInputBuffer.GetContiguousAccess(aOffset, aSize);
+  }
+
+#if defined(DEBUG)
+  void Dump(const char* aPath) { mInputBuffer.Dump(aPath); }
+#endif
+
+ private:
+  virtual ~SourceBufferResource();
+  nsresult ReadAtInternal(int64_t aOffset, char* aBuffer, uint32_t aCount,
+                          uint32_t* aBytes);
+
+#if defined(DEBUG)
+  const RefPtr<AbstractThread> mThread;
+  // TaskQueue methods and objects.
+  const AbstractThread* GetThread() const;
+  bool OnThread() const;
+#endif
+
+  // The buffer holding resource data.
+  ResourceQueue mInputBuffer;
+
+  bool mClosed = false;
+  bool mEnded = false;
+};
+
+}  // namespace mozilla
+
+#undef UNIMPLEMENTED
+
+#endif /* MOZILLA_SOURCEBUFFERRESOURCE_H_ */
diff --git a/dom/media/mediasource/SourceBufferTask.h b/dom/media/mediasource/SourceBufferTask.h
new file mode 100644
index 0000000000..34ccba1426
--- /dev/null
+++ b/dom/media/mediasource/SourceBufferTask.h
@@ -0,0 +1,126 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_SOURCEBUFFERTASK_H_
+#define MOZILLA_SOURCEBUFFERTASK_H_
+
+#include "mozilla/MozPromise.h"
+#include "SourceBufferAttributes.h"
+#include "TimeUnits.h"
+#include "MediaResult.h"
+
+#include <utility>
+
+namespace mozilla {
+
+class SourceBufferTask {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(SourceBufferTask);
+  enum class Type {
+    AppendBuffer,
+    Abort,
+    Reset,
+    RangeRemoval,
+    EvictData,
+    Detach,
+    ChangeType
+  };
+
+  typedef std::pair<bool, SourceBufferAttributes> AppendBufferResult;
+  typedef MozPromise<AppendBufferResult, MediaResult, /* IsExclusive = */ true>
+      AppendPromise;
+  typedef MozPromise<bool, nsresult, /* IsExclusive = */ true>
+      RangeRemovalPromise;
+
+  virtual Type GetType() const = 0;
+  virtual const char* GetTypeName() const = 0;
+
+  template <typename ReturnType>
+  ReturnType* As() {
+    MOZ_ASSERT(this->GetType() == ReturnType::sType);
+    return static_cast<ReturnType*>(this);
+  }
+
+ protected:
+  virtual ~SourceBufferTask() = default;
+};
+
+class AppendBufferTask : public SourceBufferTask {
+ public:
+  AppendBufferTask(already_AddRefed<MediaByteBuffer> aData,
+                   const SourceBufferAttributes& aAttributes)
+      : mBuffer(aData), mAttributes(aAttributes) {}
+
+  static const Type sType = Type::AppendBuffer;
+  Type GetType() const override { return Type::AppendBuffer; }
+  const char* GetTypeName() const override { return "AppendBuffer"; }
+
+  RefPtr<MediaByteBuffer> mBuffer;
+  SourceBufferAttributes mAttributes;
+  MozPromiseHolder<AppendPromise> mPromise;
+};
+
+class AbortTask : public SourceBufferTask {
+ public:
+  static const Type sType = Type::Abort;
+  Type GetType() const override { return Type::Abort; }
+  const char* GetTypeName() const override { return "Abort"; }
+};
+
+class ResetTask : public SourceBufferTask {
+ public:
+  static const Type sType = Type::Reset;
+  Type GetType() const override { return Type::Reset; }
+  const char* GetTypeName() const override { return "Reset"; }
+};
+
+class RangeRemovalTask : public SourceBufferTask {
+ public:
+  explicit RangeRemovalTask(const media::TimeInterval& aRange)
+      : mRange(aRange) {}
+
+  static const Type sType = Type::RangeRemoval;
+  Type GetType() const override { return Type::RangeRemoval; }
+  const char* GetTypeName() const override { return "RangeRemoval"; }
+
+  media::TimeInterval mRange;
+  MozPromiseHolder<RangeRemovalPromise> mPromise;
+};
+
+class EvictDataTask : public SourceBufferTask {
+ public:
+  EvictDataTask(const media::TimeUnit& aPlaybackTime, int64_t aSizetoEvict)
+      : mPlaybackTime(aPlaybackTime), mSizeToEvict(aSizetoEvict) {}
+
+  static const Type sType = Type::EvictData;
+  Type GetType() const override { return Type::EvictData; }
+  const char* GetTypeName() const override { return "EvictData"; }
+
+  media::TimeUnit mPlaybackTime;
+  int64_t mSizeToEvict;
+};
+
+class DetachTask : public SourceBufferTask {
+ public:
+  static const Type sType = Type::Detach;
+  Type GetType() const override { return Type::Detach; }
+  const char* GetTypeName() const override { return "Detach"; }
+};
+
+class ChangeTypeTask : public SourceBufferTask {
+ public:
+  explicit ChangeTypeTask(const MediaContainerType& aType) : mType(aType) {}
+
+  static const Type sType = Type::ChangeType;
+  Type GetType() const override { return Type::ChangeType; }
+  const char* GetTypeName() const override { return "ChangeType"; }
+
+  const MediaContainerType mType;
+};
+
+}  // namespace mozilla
+
+#endif
diff --git a/dom/media/mediasource/TrackBuffersManager.cpp b/dom/media/mediasource/TrackBuffersManager.cpp
new file mode 100644
index 0000000000..4551554dfd
--- /dev/null
+++ b/dom/media/mediasource/TrackBuffersManager.cpp
@@ -0,0 +1,3087 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "TrackBuffersManager.h"
+#include "ContainerParser.h"
+#include "MediaSourceDemuxer.h"
+#include "MediaSourceUtils.h"
+#include "SourceBuffer.h"
+#include "SourceBufferResource.h"
+#include "SourceBufferTask.h"
+#include "WebMDemuxer.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/ProfilerLabels.h"
+#include "mozilla/ProfilerMarkers.h"
+#include "mozilla/StaticPrefs_media.h"
+#include "nsMimeTypes.h"
+
+#ifdef MOZ_FMP4
+#  include "MP4Demuxer.h"
+#endif
+
+#include <limits>
+
+extern mozilla::LogModule* GetMediaSourceLog();
+
+#define MSE_DEBUG(arg, ...)                                              \
+  DDMOZ_LOG(GetMediaSourceLog(), mozilla::LogLevel::Debug, "::%s: " arg, \
+            __func__, ##__VA_ARGS__)
+#define MSE_DEBUGV(arg, ...)                                               \
+  DDMOZ_LOG(GetMediaSourceLog(), mozilla::LogLevel::Verbose, "::%s: " arg, \
+            __func__, ##__VA_ARGS__)
+
+mozilla::LogModule* GetMediaSourceSamplesLog() {
+  static mozilla::LazyLogModule sLogModule("MediaSourceSamples");
+  return sLogModule;
+}
+#define SAMPLE_DEBUG(arg, ...)                                    \
+  DDMOZ_LOG(GetMediaSourceSamplesLog(), mozilla::LogLevel::Debug, \
+            "::%s: " arg, __func__, ##__VA_ARGS__)
+
+namespace mozilla {
+
+using dom::SourceBufferAppendMode;
+using media::TimeInterval;
+using media::TimeIntervals;
+using media::TimeUnit;
+typedef SourceBufferTask::AppendBufferResult AppendBufferResult;
+typedef SourceBufferAttributes::AppendState AppendState;
+
+static const char* AppendStateToStr(AppendState aState) {
+  switch (aState) {
+    case AppendState::WAITING_FOR_SEGMENT:
+      return "WAITING_FOR_SEGMENT";
+    case AppendState::PARSING_INIT_SEGMENT:
+      return "PARSING_INIT_SEGMENT";
+    case AppendState::PARSING_MEDIA_SEGMENT:
+      return "PARSING_MEDIA_SEGMENT";
+    default:
+      return "IMPOSSIBLE";
+  }
+}
+
+static Atomic<uint32_t> sStreamSourceID(0u);
+
+class DispatchKeyNeededEvent : public Runnable {
+ public:
+  DispatchKeyNeededEvent(MediaSourceDecoder* aDecoder,
+                         const nsTArray<uint8_t>& aInitData,
+                         const nsString& aInitDataType)
+      : Runnable("DispatchKeyNeededEvent"),
+        mDecoder(aDecoder),
+        mInitData(aInitData.Clone()),
+        mInitDataType(aInitDataType) {}
+  NS_IMETHOD Run() override {
+    // Note: Null check the owner, as the decoder could have been shutdown
+    // since this event was dispatched.
+    MediaDecoderOwner* owner = mDecoder->GetOwner();
+    if (owner) {
+      owner->DispatchEncrypted(mInitData, mInitDataType);
+    }
+    mDecoder = nullptr;
+    return NS_OK;
+  }
+
+ private:
+  RefPtr<MediaSourceDecoder> mDecoder;
+  nsTArray<uint8_t> mInitData;
+  nsString mInitDataType;
+};
+
+TrackBuffersManager::TrackBuffersManager(MediaSourceDecoder* aParentDecoder,
+                                         const MediaContainerType& aType)
+    : mBufferFull(false),
+      mFirstInitializationSegmentReceived(false),
+      mChangeTypeReceived(false),
+      mNewMediaSegmentStarted(false),
+      mActiveTrack(false),
+      mType(aType),
+      mParser(ContainerParser::CreateForMIMEType(aType)),
+      mProcessedInput(0),
+      mParentDecoder(new nsMainThreadPtrHolder<MediaSourceDecoder>(
+          "TrackBuffersManager::mParentDecoder", aParentDecoder,
+          false /* strict */)),
+      mAbstractMainThread(aParentDecoder->AbstractMainThread()),
+      mEnded(false),
+      mVideoEvictionThreshold(Preferences::GetUint(
+          "media.mediasource.eviction_threshold.video", 100 * 1024 * 1024)),
+      mAudioEvictionThreshold(Preferences::GetUint(
+          "media.mediasource.eviction_threshold.audio", 20 * 1024 * 1024)),
+      mEvictionState(EvictionState::NO_EVICTION_NEEDED),
+      mMutex("TrackBuffersManager"),
+      mTaskQueue(aParentDecoder->GetDemuxer()->GetTaskQueue()),
+      mTaskQueueCapability(Some(EventTargetCapability{mTaskQueue.get()})) {
+  MOZ_ASSERT(NS_IsMainThread(), "Must be instanciated on the main thread");
+  DDLINKCHILD("parser", mParser.get());
+}
+
+TrackBuffersManager::~TrackBuffersManager() { ShutdownDemuxers(); }
+
+RefPtr<TrackBuffersManager::AppendPromise> TrackBuffersManager::AppendData(
+    already_AddRefed<MediaByteBuffer> aData,
+    const SourceBufferAttributes& aAttributes) {
+  MOZ_ASSERT(NS_IsMainThread());
+  RefPtr<MediaByteBuffer> data(aData);
+  MSE_DEBUG("Appending %zu bytes", data->Length());
+
+  mEnded = false;
+
+  return InvokeAsync(static_cast<AbstractThread*>(GetTaskQueueSafe().get()),
+                     this, __func__, &TrackBuffersManager::DoAppendData,
+                     data.forget(), aAttributes);
+}
+
+RefPtr<TrackBuffersManager::AppendPromise> TrackBuffersManager::DoAppendData(
+    already_AddRefed<MediaByteBuffer> aData,
+    const SourceBufferAttributes& aAttributes) {
+  RefPtr<AppendBufferTask> task =
+      new AppendBufferTask(std::move(aData), aAttributes);
+  RefPtr<AppendPromise> p = task->mPromise.Ensure(__func__);
+  QueueTask(task);
+
+  return p;
+}
+
+void TrackBuffersManager::QueueTask(SourceBufferTask* aTask) {
+  // The source buffer is a wrapped native, it would be unlinked twice and so
+  // the TrackBuffersManager::Detach() would also be called twice. Since the
+  // detach task has been done before, we could ignore this task.
+  RefPtr<TaskQueue> taskQueue = GetTaskQueueSafe();
+  if (!taskQueue) {
+    MOZ_ASSERT(aTask->GetType() == SourceBufferTask::Type::Detach,
+               "only detach task could happen here!");
+    MSE_DEBUG("Could not queue the task '%s' without task queue",
+              aTask->GetTypeName());
+    return;
+  }
+
+  if (!taskQueue->IsCurrentThreadIn()) {
+    nsresult rv =
+        taskQueue->Dispatch(NewRunnableMethod<RefPtr<SourceBufferTask>>(
+            "TrackBuffersManager::QueueTask", this,
+            &TrackBuffersManager::QueueTask, aTask));
+    MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(rv));
+    Unused << rv;
+    return;
+  }
+  mQueue.Push(aTask);
+  ProcessTasks();
+}
+
+void TrackBuffersManager::ProcessTasks() {
+  // ProcessTask is always called OnTaskQueue, however it is possible that it is
+  // called once again after a first Detach task has run, in which case
+  // mTaskQueue would be null.
+  // This can happen under two conditions:
+  // 1- Two Detach tasks were queued in a row due to a double cycle collection.
+  // 2- An call to ProcessTasks() had queued another run of ProcessTasks while
+  //    a Detach task is pending.
+  // We handle these two cases by aborting early.
+  // A second Detach task was queued, prior the first one running, ignore it.
+  if (!mTaskQueue) {
+    RefPtr<SourceBufferTask> task = mQueue.Pop();
+    if (!task) {
+      return;
+    }
+    MOZ_RELEASE_ASSERT(task->GetType() == SourceBufferTask::Type::Detach,
+                       "only detach task could happen here!");
+    MSE_DEBUG("Could not process the task '%s' after detached",
+              task->GetTypeName());
+    return;
+  }
+
+  mTaskQueueCapability->AssertOnCurrentThread();
+  typedef SourceBufferTask::Type Type;
+
+  if (mCurrentTask) {
+    // Already have a task pending. ProcessTask will be scheduled once the
+    // current task complete.
+    return;
+  }
+  RefPtr<SourceBufferTask> task = mQueue.Pop();
+  if (!task) {
+    // nothing to do.
+    return;
+  }
+
+  MSE_DEBUG("Process task '%s'", task->GetTypeName());
+  switch (task->GetType()) {
+    case Type::AppendBuffer:
+      mCurrentTask = task;
+      if (!mInputBuffer || mInputBuffer->IsEmpty()) {
+        // Note: we reset mInputBuffer here to ensure it doesn't grow unbounded.
+        mInputBuffer.reset();
+        mInputBuffer = Some(MediaSpan(task->As<AppendBufferTask>()->mBuffer));
+      } else {
+        // mInputBuffer wasn't empty, so we can't just reset it, but we move
+        // the data into a new buffer to clear out data no longer in the span.
+        MSE_DEBUG(
+            "mInputBuffer not empty during append -- data will be copied to "
+            "new buffer. mInputBuffer->Length()=%zu "
+            "mInputBuffer->Buffer()->Length()=%zu",
+            mInputBuffer->Length(), mInputBuffer->Buffer()->Length());
+        const RefPtr<MediaByteBuffer> newBuffer{new MediaByteBuffer()};
+        // Set capacity outside of ctor to let us explicitly handle OOM.
+        const size_t newCapacity =
+            mInputBuffer->Length() +
+            task->As<AppendBufferTask>()->mBuffer->Length();
+        if (!newBuffer->SetCapacity(newCapacity, fallible)) {
+          RejectAppend(NS_ERROR_OUT_OF_MEMORY, __func__);
+          return;
+        }
+        // Use infallible appends as we've already set capacity above.
+        newBuffer->AppendElements(mInputBuffer->Elements(),
+                                  mInputBuffer->Length());
+        newBuffer->AppendElements(*task->As<AppendBufferTask>()->mBuffer);
+        mInputBuffer = Some(MediaSpan(newBuffer));
+      }
+      mSourceBufferAttributes = MakeUnique<SourceBufferAttributes>(
+          task->As<AppendBufferTask>()->mAttributes);
+      mAppendWindow = TimeInterval(
+          TimeUnit::FromSeconds(
+              mSourceBufferAttributes->GetAppendWindowStart()),
+          TimeUnit::FromSeconds(mSourceBufferAttributes->GetAppendWindowEnd()));
+      ScheduleSegmentParserLoop();
+      break;
+    case Type::RangeRemoval: {
+      bool rv = CodedFrameRemoval(task->As<RangeRemovalTask>()->mRange);
+      task->As<RangeRemovalTask>()->mPromise.Resolve(rv, __func__);
+      break;
+    }
+    case Type::EvictData:
+      DoEvictData(task->As<EvictDataTask>()->mPlaybackTime,
+                  task->As<EvictDataTask>()->mSizeToEvict);
+      break;
+    case Type::Abort:
+      // not handled yet, and probably never.
+      break;
+    case Type::Reset:
+      CompleteResetParserState();
+      break;
+    case Type::Detach:
+      mCurrentInputBuffer = nullptr;
+      MOZ_DIAGNOSTIC_ASSERT(mQueue.Length() == 0,
+                            "Detach task must be the last");
+      mVideoTracks.Reset();
+      mAudioTracks.Reset();
+      ShutdownDemuxers();
+      ResetTaskQueue();
+      return;
+    case Type::ChangeType:
+      MOZ_RELEASE_ASSERT(!mCurrentTask);
+      MSE_DEBUG("Processing type change from %s -> %s",
+                mType.OriginalString().get(),
+                task->As<ChangeTypeTask>()->mType.OriginalString().get());
+      mType = task->As<ChangeTypeTask>()->mType;
+      mChangeTypeReceived = true;
+      mInitData = nullptr;
+      // A new input buffer will be created once we receive a new init segment.
+      // The first segment received after a changeType call must be an init
+      // segment.
+      mCurrentInputBuffer = nullptr;
+      CompleteResetParserState();
+      break;
+    default:
+      NS_WARNING("Invalid Task");
+  }
+  TaskQueueFromTaskQueue()->Dispatch(
+      NewRunnableMethod("TrackBuffersManager::ProcessTasks", this,
+                        &TrackBuffersManager::ProcessTasks));
+}
+
+// The MSE spec requires that we abort the current SegmentParserLoop
+// which is then followed by a call to ResetParserState.
+// However due to our asynchronous design this causes inherent difficulties.
+// As the spec behaviour is non deterministic anyway, we instead process all
+// pending frames found in the input buffer.
+void TrackBuffersManager::AbortAppendData() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_DEBUG("");
+
+  QueueTask(new AbortTask());
+}
+
+void TrackBuffersManager::ResetParserState(
+    SourceBufferAttributes& aAttributes) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_DEBUG("");
+
+  // Spec states:
+  // 1. If the append state equals PARSING_MEDIA_SEGMENT and the input buffer
+  // contains some complete coded frames, then run the coded frame processing
+  // algorithm until all of these complete coded frames have been processed.
+  // However, we will wait until all coded frames have been processed regardless
+  // of the value of append state.
+  QueueTask(new ResetTask());
+
+  // ResetParserState has some synchronous steps that much be performed now.
+  // The remaining steps will be performed once the ResetTask gets executed.
+
+  // 6. If the mode attribute equals "sequence", then set the group start
+  // timestamp to the group end timestamp
+  if (aAttributes.GetAppendMode() == SourceBufferAppendMode::Sequence) {
+    aAttributes.SetGroupStartTimestamp(aAttributes.GetGroupEndTimestamp());
+  }
+  // 8. Set append state to WAITING_FOR_SEGMENT.
+  aAttributes.SetAppendState(AppendState::WAITING_FOR_SEGMENT);
+}
+
+RefPtr<TrackBuffersManager::RangeRemovalPromise>
+TrackBuffersManager::RangeRemoval(TimeUnit aStart, TimeUnit aEnd) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_DEBUG("From %.2f to %.2f", aStart.ToSeconds(), aEnd.ToSeconds());
+
+  mEnded = false;
+
+  return InvokeAsync(static_cast<AbstractThread*>(GetTaskQueueSafe().get()),
+                     this, __func__,
+                     &TrackBuffersManager::CodedFrameRemovalWithPromise,
+                     TimeInterval(aStart, aEnd));
+}
+
+TrackBuffersManager::EvictDataResult TrackBuffersManager::EvictData(
+    const TimeUnit& aPlaybackTime, int64_t aSize) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (aSize > EvictionThreshold()) {
+    // We're adding more data than we can hold.
+    return EvictDataResult::BUFFER_FULL;
+  }
+  const int64_t toEvict = GetSize() + aSize - EvictionThreshold();
+
+  const uint32_t canEvict =
+      Evictable(HasVideo() ? TrackInfo::kVideoTrack : TrackInfo::kAudioTrack);
+
+  MSE_DEBUG("currentTime=%" PRId64 " buffered=%" PRId64
+            "kB, eviction threshold=%" PRId64
+            "kB, "
+            "evict=%" PRId64 "kB canevict=%" PRIu32 "kB",
+            aPlaybackTime.ToMicroseconds(), GetSize() / 1024,
+            EvictionThreshold() / 1024, toEvict / 1024, canEvict / 1024);
+
+  if (toEvict <= 0) {
+    mEvictionState = EvictionState::NO_EVICTION_NEEDED;
+    return EvictDataResult::NO_DATA_EVICTED;
+  }
+
+  EvictDataResult result;
+
+  if (mBufferFull && mEvictionState == EvictionState::EVICTION_COMPLETED &&
+      canEvict < uint32_t(toEvict)) {
+    // Our buffer is currently full. We will make another eviction attempt.
+    // However, the current appendBuffer will fail as we can't know ahead of
+    // time if the eviction will later succeed.
+    result = EvictDataResult::BUFFER_FULL;
+  } else {
+    mEvictionState = EvictionState::EVICTION_NEEDED;
+    result = EvictDataResult::NO_DATA_EVICTED;
+  }
+  MSE_DEBUG("Reached our size limit, schedule eviction of %" PRId64
+            " bytes (%s)",
+            toEvict,
+            result == EvictDataResult::BUFFER_FULL ? "buffer full"
+                                                   : "no data evicted");
+  QueueTask(new EvictDataTask(aPlaybackTime, toEvict));
+
+  return result;
+}
+
+void TrackBuffersManager::ChangeType(const MediaContainerType& aType) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  QueueTask(new ChangeTypeTask(aType));
+}
+
+TimeIntervals TrackBuffersManager::Buffered() const {
+  MSE_DEBUG("");
+
+  // http://w3c.github.io/media-source/index.html#widl-SourceBuffer-buffered
+
+  MutexAutoLock mut(mMutex);
+  nsTArray<const TimeIntervals*> tracks;
+  if (HasVideo()) {
+    tracks.AppendElement(&mVideoBufferedRanges);
+  }
+  if (HasAudio()) {
+    tracks.AppendElement(&mAudioBufferedRanges);
+  }
+
+  // 2. Let highest end time be the largest track buffer ranges end time across
+  // all the track buffers managed by this SourceBuffer object.
+  TimeUnit highestEndTime = HighestEndTime(tracks);
+
+  // 3. Let intersection ranges equal a TimeRange object containing a single
+  // range from 0 to highest end time.
+  TimeIntervals intersection{
+      TimeInterval(TimeUnit::FromSeconds(0), highestEndTime)};
+
+  // 4. For each track buffer managed by this SourceBuffer, run the following
+  // steps:
+  //   1. Let track ranges equal the track buffer ranges for the current track
+  //   buffer.
+  for (const TimeIntervals* trackRanges : tracks) {
+    // 2. If readyState is "ended", then set the end time on the last range in
+    // track ranges to highest end time.
+    // 3. Let new intersection ranges equal the intersection between the
+    // intersection ranges and the track ranges.
+    if (mEnded) {
+      TimeIntervals tR = *trackRanges;
+      tR.Add(TimeInterval(tR.GetEnd(), highestEndTime));
+      intersection.Intersection(tR);
+    } else {
+      intersection.Intersection(*trackRanges);
+    }
+  }
+  return intersection;
+}
+
+int64_t TrackBuffersManager::GetSize() const { return mSizeSourceBuffer; }
+
+void TrackBuffersManager::Ended() { mEnded = true; }
+
+void TrackBuffersManager::Detach() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MSE_DEBUG("");
+  QueueTask(new DetachTask());
+}
+
+void TrackBuffersManager::CompleteResetParserState() {
+  mTaskQueueCapability->AssertOnCurrentThread();
+  AUTO_PROFILER_LABEL("TrackBuffersManager::CompleteResetParserState",
+                      MEDIA_PLAYBACK);
+  MSE_DEBUG("");
+
+  // We shouldn't change mInputDemuxer while a demuxer init/reset request is
+  // being processed. See bug 1239983.
+  MOZ_DIAGNOSTIC_ASSERT(!mDemuxerInitRequest.Exists(),
+                        "Previous AppendBuffer didn't complete");
+
+  for (auto& track : GetTracksList()) {
+    // 2. Unset the last decode timestamp on all track buffers.
+    // 3. Unset the last frame duration on all track buffers.
+    // 4. Unset the highest end timestamp on all track buffers.
+    // 5. Set the need random access point flag on all track buffers to true.
+    track->ResetAppendState();
+
+    // if we have been aborted, we may have pending frames that we are going
+    // to discard now.
+    track->mQueuedSamples.Clear();
+  }
+
+  // 7. Remove all bytes from the input buffer.
+  mPendingInputBuffer.reset();
+  mInputBuffer.reset();
+  if (mCurrentInputBuffer) {
+    mCurrentInputBuffer->EvictAll();
+    // The demuxer will be recreated during the next run of SegmentParserLoop.
+    // As such we don't need to notify it that data has been removed.
+    mCurrentInputBuffer = new SourceBufferResource();
+  }
+
+  // We could be left with a demuxer in an unusable state. It needs to be
+  // recreated. Unless we have a pending changeType operation, we store in the
+  // InputBuffer an init segment which will be parsed during the next Segment
+  // Parser Loop and a new demuxer will be created and initialized.
+  // If we are in the middle of a changeType operation, then we do not have an
+  // init segment yet. The next appendBuffer operation will need to provide such
+  // init segment.
+  if (mFirstInitializationSegmentReceived && !mChangeTypeReceived) {
+    MOZ_ASSERT(mInitData && mInitData->Length(),
+               "we must have an init segment");
+    // The aim here is really to destroy our current demuxer.
+    CreateDemuxerforMIMEType();
+    // Recreate our input buffer. We can't directly assign the initData buffer
+    // to mInputBuffer as it will get modified in the Segment Parser Loop.
+    mInputBuffer = Some(MediaSpan::WithCopyOf(mInitData));
+    RecreateParser(true);
+  } else {
+    RecreateParser(false);
+  }
+}
+
+int64_t TrackBuffersManager::EvictionThreshold() const {
+  if (HasVideo()) {
+    return mVideoEvictionThreshold;
+  }
+  return mAudioEvictionThreshold;
+}
+
+void TrackBuffersManager::DoEvictData(const TimeUnit& aPlaybackTime,
+                                      int64_t aSizeToEvict) {
+  mTaskQueueCapability->AssertOnCurrentThread();
+  AUTO_PROFILER_LABEL("TrackBuffersManager::DoEvictData", MEDIA_PLAYBACK);
+
+  mEvictionState = EvictionState::EVICTION_COMPLETED;
+
+  // Video is what takes the most space, only evict there if we have video.
+  auto& track = HasVideo() ? mVideoTracks : mAudioTracks;
+  const auto& buffer = track.GetTrackBuffer();
+  if (buffer.IsEmpty()) {
+    // Buffer has been emptied while the eviction was queued, nothing to do.
+    return;
+  }
+  if (track.mBufferedRanges.IsEmpty()) {
+    MSE_DEBUG(
+        "DoEvictData running with no buffered ranges. 0 duration data likely "
+        "present in our buffer(s). Evicting all data!");
+    // We have no buffered ranges, but may still have data. This happens if the
+    // buffer is full of 0 duration data. Normal removal procedures don't clear
+    // 0 duration data, so blow away all our data.
+    RemoveAllCodedFrames();
+    return;
+  }
+  // Remove any data we've already played, or before the next sample to be
+  // demuxed whichever is lowest.
+  TimeUnit lowerLimit = std::min(track.mNextSampleTime, aPlaybackTime);
+  uint32_t lastKeyFrameIndex = 0;
+  int64_t toEvict = aSizeToEvict;
+  int64_t partialEvict = 0;
+  for (uint32_t i = 0; i < buffer.Length(); i++) {
+    const auto& frame = buffer[i];
+    if (frame->mKeyframe) {
+      lastKeyFrameIndex = i;
+      toEvict -= partialEvict;
+      if (toEvict < 0) {
+        break;
+      }
+      partialEvict = 0;
+    }
+    if (frame->GetEndTime() >= lowerLimit) {
+      break;
+    }
+    partialEvict += frame->ComputedSizeOfIncludingThis();
+  }
+
+  const int64_t finalSize = mSizeSourceBuffer - aSizeToEvict;
+
+  if (lastKeyFrameIndex > 0) {
+    MSE_DEBUG("Step1. Evicting %" PRId64 " bytes prior currentTime",
+              aSizeToEvict - toEvict);
+    TimeUnit start = track.mBufferedRanges[0].mStart;
+    TimeUnit end =
+        buffer[lastKeyFrameIndex]->mTime - TimeUnit::FromMicroseconds(1);
+    if (end > start) {
+      CodedFrameRemoval(TimeInterval(start, end));
+    }
+  }
+
+  if (mSizeSourceBuffer <= finalSize) {
+    return;
+  }
+
+  toEvict = mSizeSourceBuffer - finalSize;
+
+  // See if we can evict data into the future.
+  // We do not evict data from the currently used buffered interval.
+
+  TimeUnit currentPosition = std::max(aPlaybackTime, track.mNextSampleTime);
+  TimeIntervals futureBuffered(
+      TimeInterval(currentPosition, TimeUnit::FromInfinity()));
+  futureBuffered.Intersection(track.mBufferedRanges);
+  futureBuffered.SetFuzz(MediaSourceDemuxer::EOS_FUZZ / 2);
+  if (futureBuffered.Length() <= 1) {
+    // We have one continuous segment ahead of us:
+    // nothing further can be evicted.
+    return;
+  }
+
+  // Don't evict before the end of the current segment
+  TimeUnit upperLimit = futureBuffered[0].mEnd;
+  uint32_t evictedFramesStartIndex = buffer.Length();
+  for (int32_t i = buffer.Length() - 1; i >= 0; i--) {
+    const auto& frame = buffer[i];
+    if (frame->mTime <= upperLimit || toEvict < 0) {
+      // We've reached a frame that shouldn't be evicted -> Evict after it ->
+      // i+1. Or the previous loop reached the eviction threshold -> Evict from
+      // it -> i+1.
+      evictedFramesStartIndex = i + 1;
+      break;
+    }
+    toEvict -= frame->ComputedSizeOfIncludingThis();
+  }
+  if (evictedFramesStartIndex < buffer.Length()) {
+    MSE_DEBUG("Step2. Evicting %" PRId64 " bytes from trailing data",
+              mSizeSourceBuffer - finalSize - toEvict);
+    CodedFrameRemoval(TimeInterval(buffer[evictedFramesStartIndex]->mTime,
+                                   TimeUnit::FromInfinity()));
+  }
+}
+
+RefPtr<TrackBuffersManager::RangeRemovalPromise>
+TrackBuffersManager::CodedFrameRemovalWithPromise(TimeInterval aInterval) {
+  mTaskQueueCapability->AssertOnCurrentThread();
+
+  RefPtr<RangeRemovalTask> task = new RangeRemovalTask(aInterval);
+  RefPtr<RangeRemovalPromise> p = task->mPromise.Ensure(__func__);
+  QueueTask(task);
+
+  return p;
+}
+
+bool TrackBuffersManager::CodedFrameRemoval(TimeInterval aInterval) {
+  MOZ_ASSERT(OnTaskQueue());
+  AUTO_PROFILER_LABEL("TrackBuffersManager::CodedFrameRemoval", MEDIA_PLAYBACK);
+  MSE_DEBUG("From %.2fs to %.2f", aInterval.mStart.ToSeconds(),
+            aInterval.mEnd.ToSeconds());
+
+#if DEBUG
+  if (HasVideo()) {
+    MSE_DEBUG("before video ranges=%s",
+              DumpTimeRanges(mVideoTracks.mBufferedRanges).get());
+  }
+  if (HasAudio()) {
+    MSE_DEBUG("before audio ranges=%s",
+              DumpTimeRanges(mAudioTracks.mBufferedRanges).get());
+  }
+#endif
+
+  // 1. Let start be the starting presentation timestamp for the removal range.
+  TimeUnit start = aInterval.mStart;
+  // 2. Let end be the end presentation timestamp for the removal range.
+  TimeUnit end = aInterval.mEnd;
+
+  bool dataRemoved = false;
+
+  // 3. For each track buffer in this source buffer, run the following steps:
+  for (auto track : GetTracksList()) {
+    MSE_DEBUGV("Processing %s track", track->mInfo->mMimeType.get());
+    // 1. Let remove end timestamp be the current value of duration
+    // See bug: https://www.w3.org/Bugs/Public/show_bug.cgi?id=28727
+    // At worse we will remove all frames until the end, unless a key frame is
+    // found between the current interval's end and the trackbuffer's end.
+    TimeUnit removeEndTimestamp = track->mBufferedRanges.GetEnd();
+
+    if (start > removeEndTimestamp) {
+      // Nothing to remove.
+      continue;
+    }
+
+    // 2. If this track buffer has a random access point timestamp that is
+    // greater than or equal to end, then update remove end timestamp to that
+    // random access point timestamp.
+    if (end < track->mBufferedRanges.GetEnd()) {
+      for (auto& frame : track->GetTrackBuffer()) {
+        if (frame->mKeyframe && frame->mTime >= end) {
+          removeEndTimestamp = frame->mTime;
+          break;
+        }
+      }
+    }
+
+    // 3. Remove all media data, from this track buffer, that contain starting
+    // timestamps greater than or equal to start and less than the remove end
+    // timestamp.
+    // 4. Remove decoding dependencies of the coded frames removed in the
+    // previous step: Remove all coded frames between the coded frames removed
+    // in the previous step and the next random access point after those removed
+    // frames.
+    TimeIntervals removedInterval{TimeInterval(start, removeEndTimestamp)};
+    RemoveFrames(removedInterval, *track, 0, RemovalMode::kRemoveFrame);
+
+    // 5. If this object is in activeSourceBuffers, the current playback
+    // position is greater than or equal to start and less than the remove end
+    // timestamp, and HTMLMediaElement.readyState is greater than HAVE_METADATA,
+    // then set the HTMLMediaElement.readyState attribute to HAVE_METADATA and
+    // stall playback. This will be done by the MDSM during playback.
+    // TODO properly, so it works even if paused.
+  }
+
+  UpdateBufferedRanges();
+
+  // Update our reported total size.
+  mSizeSourceBuffer = mVideoTracks.mSizeBuffer + mAudioTracks.mSizeBuffer;
+
+  // 4. If buffer full flag equals true and this object is ready to accept more
+  // bytes, then set the buffer full flag to false.
+  if (mBufferFull && mSizeSourceBuffer < EvictionThreshold()) {
+    mBufferFull = false;
+  }
+
+  return dataRemoved;
+}
+
+void TrackBuffersManager::RemoveAllCodedFrames() {
+  // This is similar to RemoveCodedFrames, but will attempt to remove ALL
+  // the frames. This is not to spec, as explained below at step 3.1. Steps
+  // below coincide with Remove Coded Frames algorithm from the spec.
+  MSE_DEBUG("RemoveAllCodedFrames called.");
+  MOZ_ASSERT(OnTaskQueue());
+  AUTO_PROFILER_LABEL("TrackBuffersManager::RemoveAllCodedFrames",
+                      MEDIA_PLAYBACK);
+
+  // 1. Let start be the starting presentation timestamp for the removal range.
+  TimeUnit start{};
+  // 2. Let end be the end presentation timestamp for the removal range.
+  TimeUnit end = TimeUnit::FromMicroseconds(1);
+  // Find an end time such that our range will include every frame in every
+  // track. We do this by setting the end of our interval to the largest end
+  // time seen + 1 microsecond.
+  for (TrackData* track : GetTracksList()) {
+    for (auto& frame : track->GetTrackBuffer()) {
+      MOZ_ASSERT(frame->mTime >= start,
+                 "Shouldn't have frame at negative time!");
+      TimeUnit frameEnd = frame->mTime + frame->mDuration;
+      if (frameEnd > end) {
+        end = frameEnd + TimeUnit::FromMicroseconds(1);
+      }
+    }
+  }
+
+  // 3. For each track buffer in this source buffer, run the following steps:
+  TimeIntervals removedInterval{TimeInterval(start, end)};
+  for (TrackData* track : GetTracksList()) {
+    // 1. Let remove end timestamp be the current value of duration
+    // ^ It's off spec, but we ignore this in order to clear 0 duration frames.
+    // If we don't ignore this rule and our buffer is full of 0 duration frames
+    // at timestamp n, we get an eviction range of [0, n). When we get to step
+    // 3.3 below, the 0 duration frames will not be evicted because their
+    // timestamp is not less than remove end timestamp -- it will in fact be
+    // equal to remove end timestamp.
+    //
+    // 2. If this track buffer has a random access point timestamp that is
+    // greater than or equal to end, then update remove end timestamp to that
+    // random access point timestamp.
+    // ^ We've made sure end > any sample's timestamp, so can skip this.
+    //
+    // 3. Remove all media data, from this track buffer, that contain starting
+    // timestamps greater than or equal to start and less than the remove end
+    // timestamp.
+    // 4. Remove decoding dependencies of the coded frames removed in the
+    // previous step: Remove all coded frames between the coded frames removed
+    // in the previous step and the next random access point after those removed
+    // frames.
+
+    // This should remove every frame in the track because removedInterval was
+    // constructed such that every frame in any track falls into that interval.
+    RemoveFrames(removedInterval, *track, 0, RemovalMode::kRemoveFrame);
+
+    // 5. If this object is in activeSourceBuffers, the current playback
+    // position is greater than or equal to start and less than the remove end
+    // timestamp, and HTMLMediaElement.readyState is greater than HAVE_METADATA,
+    // then set the HTMLMediaElement.readyState attribute to HAVE_METADATA and
+    // stall playback. This will be done by the MDSM during playback.
+    // TODO properly, so it works even if paused.
+  }
+
+  UpdateBufferedRanges();
+#ifdef DEBUG
+  {
+    MutexAutoLock lock(mMutex);
+    MOZ_ASSERT(
+        mAudioBufferedRanges.IsEmpty(),
+        "Should have no buffered video ranges after evicting everything.");
+    MOZ_ASSERT(
+        mVideoBufferedRanges.IsEmpty(),
+        "Should have no buffered video ranges after evicting everything.");
+  }
+#endif
+  mSizeSourceBuffer = mVideoTracks.mSizeBuffer + mAudioTracks.mSizeBuffer;
+  MOZ_ASSERT(mSizeSourceBuffer == 0,
+             "Buffer should be empty after evicting everything!");
+  if (mBufferFull && mSizeSourceBuffer < EvictionThreshold()) {
+    mBufferFull = false;
+  }
+}
+
+void TrackBuffersManager::UpdateBufferedRanges() {
+  MutexAutoLock mut(mMutex);
+
+  mVideoBufferedRanges = mVideoTracks.mSanitizedBufferedRanges;
+  mAudioBufferedRanges = mAudioTracks.mSanitizedBufferedRanges;
+
+#if DEBUG
+  if (HasVideo()) {
+    MSE_DEBUG("after video ranges=%s",
+              DumpTimeRanges(mVideoTracks.mBufferedRanges).get());
+  }
+  if (HasAudio()) {
+    MSE_DEBUG("after audio ranges=%s",
+              DumpTimeRanges(mAudioTracks.mBufferedRanges).get());
+  }
+#endif
+}
+
+void TrackBuffersManager::SegmentParserLoop() {
+  MOZ_ASSERT(OnTaskQueue());
+  AUTO_PROFILER_LABEL("TrackBuffersManager::SegmentParserLoop", MEDIA_PLAYBACK);
+
+  while (true) {
+    // 1. If the input buffer is empty, then jump to the need more data step
+    // below.
+    if (!mInputBuffer || mInputBuffer->IsEmpty()) {
+      NeedMoreData();
+      return;
+    }
+    // 2. If the input buffer contains bytes that violate the SourceBuffer
+    // byte stream format specification, then run the append error algorithm
+    // with the decode error parameter set to true and abort this algorithm.
+    // TODO
+
+    // 3. Remove any bytes that the byte stream format specifications say must
+    // be ignored from the start of the input buffer. We do not remove bytes
+    // from our input buffer. Instead we enforce that our ContainerParser is
+    // able to skip over all data that is supposed to be ignored.
+
+    // 4. If the append state equals WAITING_FOR_SEGMENT, then run the following
+    // steps:
+    if (mSourceBufferAttributes->GetAppendState() ==
+        AppendState::WAITING_FOR_SEGMENT) {
+      MediaResult haveInitSegment =
+          mParser->IsInitSegmentPresent(*mInputBuffer);
+      if (NS_SUCCEEDED(haveInitSegment)) {
+        SetAppendState(AppendState::PARSING_INIT_SEGMENT);
+        if (mFirstInitializationSegmentReceived && !mChangeTypeReceived) {
+          // This is a new initialization segment. Obsolete the old one.
+          RecreateParser(false);
+        }
+        continue;
+      }
+      MediaResult haveMediaSegment =
+          mParser->IsMediaSegmentPresent(*mInputBuffer);
+      if (NS_SUCCEEDED(haveMediaSegment)) {
+        SetAppendState(AppendState::PARSING_MEDIA_SEGMENT);
+        mNewMediaSegmentStarted = true;
+        continue;
+      }
+      // We have neither an init segment nor a media segment.
+      // Check if it was invalid data.
+      if (haveInitSegment != NS_ERROR_NOT_AVAILABLE) {
+        MSE_DEBUG("Found invalid data.");
+        RejectAppend(haveInitSegment, __func__);
+        return;
+      }
+      if (haveMediaSegment != NS_ERROR_NOT_AVAILABLE) {
+        MSE_DEBUG("Found invalid data.");
+        RejectAppend(haveMediaSegment, __func__);
+        return;
+      }
+      MSE_DEBUG("Found incomplete data.");
+      NeedMoreData();
+      return;
+    }
+
+    MOZ_ASSERT(mSourceBufferAttributes->GetAppendState() ==
+                   AppendState::PARSING_INIT_SEGMENT ||
+               mSourceBufferAttributes->GetAppendState() ==
+                   AppendState::PARSING_MEDIA_SEGMENT);
+
+    int64_t start = 0;
+    int64_t end = 0;
+    MediaResult newData = NS_ERROR_NOT_AVAILABLE;
+
+    if (mSourceBufferAttributes->GetAppendState() ==
+            AppendState::PARSING_INIT_SEGMENT ||
+        (mSourceBufferAttributes->GetAppendState() ==
+             AppendState::PARSING_MEDIA_SEGMENT &&
+         mFirstInitializationSegmentReceived && !mChangeTypeReceived)) {
+      newData = mParser->ParseStartAndEndTimestamps(*mInputBuffer, start, end);
+      if (NS_FAILED(newData) && newData.Code() != NS_ERROR_NOT_AVAILABLE) {
+        RejectAppend(newData, __func__);
+        return;
+      }
+      mProcessedInput += mInputBuffer->Length();
+    }
+
+    // 5. If the append state equals PARSING_INIT_SEGMENT, then run the
+    // following steps:
+    if (mSourceBufferAttributes->GetAppendState() ==
+        AppendState::PARSING_INIT_SEGMENT) {
+      if (mParser->InitSegmentRange().IsEmpty()) {
+        mInputBuffer.reset();
+        NeedMoreData();
+        return;
+      }
+      InitializationSegmentReceived();
+      return;
+    }
+    if (mSourceBufferAttributes->GetAppendState() ==
+        AppendState::PARSING_MEDIA_SEGMENT) {
+      // 1. If the first initialization segment received flag is false, then run
+      //    the append error algorithm with the decode error parameter set to
+      //    true and abort this algorithm.
+      //    Or we are in the process of changeType, in which case we must first
+      //    get an init segment before getting a media segment.
+      if (!mFirstInitializationSegmentReceived || mChangeTypeReceived) {
+        RejectAppend(NS_ERROR_FAILURE, __func__);
+        return;
+      }
+
+      // We can't feed some demuxers (WebMDemuxer) with data that do not have
+      // monotonizally increasing timestamps. So we check if we have a
+      // discontinuity from the previous segment parsed.
+      // If so, recreate a new demuxer to ensure that the demuxer is only fed
+      // monotonically increasing data.
+      if (mNewMediaSegmentStarted) {
+        if (NS_SUCCEEDED(newData) && mLastParsedEndTime.isSome() &&
+            start < mLastParsedEndTime.ref().ToMicroseconds()) {
+          MSE_DEBUG("Re-creating demuxer");
+          ResetDemuxingState();
+          return;
+        }
+        if (NS_SUCCEEDED(newData) || !mParser->MediaSegmentRange().IsEmpty()) {
+          if (mPendingInputBuffer) {
+            // We now have a complete media segment header. We can resume
+            // parsing the data.
+            AppendDataToCurrentInputBuffer(*mPendingInputBuffer);
+            mPendingInputBuffer.reset();
+          }
+          mNewMediaSegmentStarted = false;
+        } else {
+          // We don't have any data to demux yet, stash aside the data.
+          // This also handles the case:
+          // 2. If the input buffer does not contain a complete media segment
+          // header yet, then jump to the need more data step below.
+          if (!mPendingInputBuffer) {
+            mPendingInputBuffer = Some(MediaSpan(*mInputBuffer));
+          } else {
+            // Note we reset mInputBuffer below, so this won't end up appending
+            // the contents of mInputBuffer to itself.
+            mPendingInputBuffer->Append(*mInputBuffer);
+          }
+
+          mInputBuffer.reset();
+          NeedMoreData();
+          return;
+        }
+      }
+
+      // 3. If the input buffer contains one or more complete coded frames, then
+      // run the coded frame processing algorithm.
+      RefPtr<TrackBuffersManager> self = this;
+      CodedFrameProcessing()
+          ->Then(
+              TaskQueueFromTaskQueue(), __func__,
+              [self](bool aNeedMoreData) {
+                self->mTaskQueueCapability->AssertOnCurrentThread();
+                self->mProcessingRequest.Complete();
+                if (aNeedMoreData) {
+                  self->NeedMoreData();
+                } else {
+                  self->ScheduleSegmentParserLoop();
+                }
+              },
+              [self](const MediaResult& aRejectValue) {
+                self->mTaskQueueCapability->AssertOnCurrentThread();
+                self->mProcessingRequest.Complete();
+                self->RejectAppend(aRejectValue, __func__);
+              })
+          ->Track(mProcessingRequest);
+      return;
+    }
+  }
+}
+
+void TrackBuffersManager::NeedMoreData() {
+  MSE_DEBUG("");
+  MOZ_DIAGNOSTIC_ASSERT(mCurrentTask &&
+                        mCurrentTask->GetType() ==
+                            SourceBufferTask::Type::AppendBuffer);
+  MOZ_DIAGNOSTIC_ASSERT(mSourceBufferAttributes);
+
+  mCurrentTask->As<AppendBufferTask>()->mPromise.Resolve(
+      SourceBufferTask::AppendBufferResult(mActiveTrack,
+                                           *mSourceBufferAttributes),
+      __func__);
+  mSourceBufferAttributes = nullptr;
+  mCurrentTask = nullptr;
+  ProcessTasks();
+}
+
+void TrackBuffersManager::RejectAppend(const MediaResult& aRejectValue,
+                                       const char* aName) {
+  MSE_DEBUG("rv=%" PRIu32, static_cast<uint32_t>(aRejectValue.Code()));
+  MOZ_DIAGNOSTIC_ASSERT(mCurrentTask &&
+                        mCurrentTask->GetType() ==
+                            SourceBufferTask::Type::AppendBuffer);
+
+  mCurrentTask->As<AppendBufferTask>()->mPromise.Reject(aRejectValue, __func__);
+  mSourceBufferAttributes = nullptr;
+  mCurrentTask = nullptr;
+  ProcessTasks();
+}
+
+void TrackBuffersManager::ScheduleSegmentParserLoop() {
+  MOZ_ASSERT(OnTaskQueue());
+  TaskQueueFromTaskQueue()->Dispatch(
+      NewRunnableMethod("TrackBuffersManager::SegmentParserLoop", this,
+                        &TrackBuffersManager::SegmentParserLoop));
+}
+
+void TrackBuffersManager::ShutdownDemuxers() {
+  if (mVideoTracks.mDemuxer) {
+    mVideoTracks.mDemuxer->BreakCycles();
+    mVideoTracks.mDemuxer = nullptr;
+  }
+  if (mAudioTracks.mDemuxer) {
+    mAudioTracks.mDemuxer->BreakCycles();
+    mAudioTracks.mDemuxer = nullptr;
+  }
+  // We shouldn't change mInputDemuxer while a demuxer init/reset request is
+  // being processed. See bug 1239983.
+  MOZ_DIAGNOSTIC_ASSERT(!mDemuxerInitRequest.Exists());
+  mInputDemuxer = nullptr;
+  mLastParsedEndTime.reset();
+}
+
+void TrackBuffersManager::CreateDemuxerforMIMEType() {
+  mTaskQueueCapability->AssertOnCurrentThread();
+  MSE_DEBUG("mType.OriginalString=%s", mType.OriginalString().get());
+  ShutdownDemuxers();
+
+  if (mType.Type() == MEDIAMIMETYPE(VIDEO_WEBM) ||
+      mType.Type() == MEDIAMIMETYPE(AUDIO_WEBM)) {
+    mInputDemuxer =
+        new WebMDemuxer(mCurrentInputBuffer, true /* IsMediaSource*/);
+    DDLINKCHILD("demuxer", mInputDemuxer.get());
+    return;
+  }
+
+#ifdef MOZ_FMP4
+  if (mType.Type() == MEDIAMIMETYPE(VIDEO_MP4) ||
+      mType.Type() == MEDIAMIMETYPE(AUDIO_MP4)) {
+    mInputDemuxer = new MP4Demuxer(mCurrentInputBuffer);
+    DDLINKCHILD("demuxer", mInputDemuxer.get());
+    return;
+  }
+#endif
+  NS_WARNING("Not supported (yet)");
+}
+
+// We reset the demuxer by creating a new one and initializing it.
+void TrackBuffersManager::ResetDemuxingState() {
+  MOZ_ASSERT(OnTaskQueue());
+  MOZ_ASSERT(mParser && mParser->HasInitData());
+  AUTO_PROFILER_LABEL("TrackBuffersManager::ResetDemuxingState",
+                      MEDIA_PLAYBACK);
+  RecreateParser(true);
+  mCurrentInputBuffer = new SourceBufferResource();
+  // The demuxer isn't initialized yet ; we don't want to notify it
+  // that data has been appended yet ; so we simply append the init segment
+  // to the resource.
+  mCurrentInputBuffer->AppendData(mParser->InitData());
+  CreateDemuxerforMIMEType();
+  if (!mInputDemuxer) {
+    RejectAppend(NS_ERROR_FAILURE, __func__);
+    return;
+  }
+  mInputDemuxer->Init()
+      ->Then(TaskQueueFromTaskQueue(), __func__, this,
+             &TrackBuffersManager::OnDemuxerResetDone,
+             &TrackBuffersManager::OnDemuxerInitFailed)
+      ->Track(mDemuxerInitRequest);
+}
+
+void TrackBuffersManager::OnDemuxerResetDone(const MediaResult& aResult) {
+  MOZ_ASSERT(OnTaskQueue());
+  mDemuxerInitRequest.Complete();
+
+  if (NS_FAILED(aResult) && StaticPrefs::media_playback_warnings_as_errors()) {
+    RejectAppend(aResult, __func__);
+    return;
+  }
+
+  // mInputDemuxer shouldn't have been destroyed while a demuxer init/reset
+  // request was being processed. See bug 1239983.
+  MOZ_DIAGNOSTIC_ASSERT(mInputDemuxer);
+
+  if (aResult != NS_OK && mParentDecoder) {
+    RefPtr<TrackBuffersManager> self = this;
+    mAbstractMainThread->Dispatch(NS_NewRunnableFunction(
+        "TrackBuffersManager::OnDemuxerResetDone", [self, aResult]() {
+          if (self->mParentDecoder && self->mParentDecoder->GetOwner()) {
+            self->mParentDecoder->GetOwner()->DecodeWarning(aResult);
+          }
+        }));
+  }
+
+  // Recreate track demuxers.
+  uint32_t numVideos = mInputDemuxer->GetNumberTracks(TrackInfo::kVideoTrack);
+  if (numVideos) {
+    // We currently only handle the first video track.
+    mVideoTracks.mDemuxer =
+        mInputDemuxer->GetTrackDemuxer(TrackInfo::kVideoTrack, 0);
+    MOZ_ASSERT(mVideoTracks.mDemuxer);
+    DDLINKCHILD("video demuxer", mVideoTracks.mDemuxer.get());
+  }
+
+  uint32_t numAudios = mInputDemuxer->GetNumberTracks(TrackInfo::kAudioTrack);
+  if (numAudios) {
+    // We currently only handle the first audio track.
+    mAudioTracks.mDemuxer =
+        mInputDemuxer->GetTrackDemuxer(TrackInfo::kAudioTrack, 0);
+    MOZ_ASSERT(mAudioTracks.mDemuxer);
+    DDLINKCHILD("audio demuxer", mAudioTracks.mDemuxer.get());
+  }
+
+  if (mPendingInputBuffer) {
+    // We had a partial media segment header stashed aside.
+    // Reparse its content so we can continue parsing the current input buffer.
+    int64_t start, end;
+    mParser->ParseStartAndEndTimestamps(*mPendingInputBuffer, start, end);
+    mProcessedInput += mPendingInputBuffer->Length();
+  }
+
+  SegmentParserLoop();
+}
+
+void TrackBuffersManager::AppendDataToCurrentInputBuffer(
+    const MediaSpan& aData) {
+  MOZ_ASSERT(mCurrentInputBuffer);
+  mCurrentInputBuffer->AppendData(aData);
+  mInputDemuxer->NotifyDataArrived();
+}
+
+void TrackBuffersManager::InitializationSegmentReceived() {
+  MOZ_ASSERT(OnTaskQueue());
+  MOZ_ASSERT(mParser->HasCompleteInitData());
+  AUTO_PROFILER_LABEL("TrackBuffersManager::InitializationSegmentReceived",
+                      MEDIA_PLAYBACK);
+
+  int64_t endInit = mParser->InitSegmentRange().mEnd;
+  if (mInputBuffer->Length() > mProcessedInput ||
+      int64_t(mProcessedInput - mInputBuffer->Length()) > endInit) {
+    // Something is not quite right with the data appended. Refuse it.
+    RejectAppend(MediaResult(NS_ERROR_FAILURE,
+                             "Invalid state following initialization segment"),
+                 __func__);
+    return;
+  }
+
+  mCurrentInputBuffer = new SourceBufferResource();
+  // The demuxer isn't initialized yet ; we don't want to notify it
+  // that data has been appended yet ; so we simply append the init segment
+  // to the resource.
+  mCurrentInputBuffer->AppendData(mParser->InitData());
+  uint32_t length = endInit - (mProcessedInput - mInputBuffer->Length());
+  MOZ_RELEASE_ASSERT(length <= mInputBuffer->Length());
+  mInputBuffer->RemoveFront(length);
+  CreateDemuxerforMIMEType();
+  if (!mInputDemuxer) {
+    NS_WARNING("TODO type not supported");
+    RejectAppend(NS_ERROR_DOM_NOT_SUPPORTED_ERR, __func__);
+    return;
+  }
+  mInputDemuxer->Init()
+      ->Then(TaskQueueFromTaskQueue(), __func__, this,
+             &TrackBuffersManager::OnDemuxerInitDone,
+             &TrackBuffersManager::OnDemuxerInitFailed)
+      ->Track(mDemuxerInitRequest);
+}
+
+bool TrackBuffersManager::IsRepeatInitData(
+    const MediaInfo& aNewMediaInfo) const {
+  MOZ_ASSERT(OnTaskQueue());
+  if (!mInitData) {
+    // There is no previous init data, so this cannot be a repeat.
+    return false;
+  }
+
+  if (mChangeTypeReceived) {
+    // If we're received change type we want to reprocess init data.
+    return false;
+  }
+
+  MOZ_DIAGNOSTIC_ASSERT(mInitData, "Init data should be non-null");
+  if (*mInitData == *mParser->InitData()) {
+    // We have previous init data, and it's the same binary data as we've just
+    // parsed.
+    return true;
+  }
+
+  // At this point the binary data doesn't match, but it's possible to have the
+  // different binary representations for the same logical init data. These
+  // checks can be revised as we encounter such cases in the wild.
+
+  bool audioInfoIsRepeat = false;
+  if (aNewMediaInfo.HasAudio()) {
+    if (!mAudioTracks.mLastInfo) {
+      // There is no old audio info, so this can't be a repeat.
+      return false;
+    }
+    audioInfoIsRepeat =
+        *mAudioTracks.mLastInfo->GetAsAudioInfo() == aNewMediaInfo.mAudio;
+    if (!aNewMediaInfo.HasVideo()) {
+      // Only have audio.
+      return audioInfoIsRepeat;
+    }
+  }
+
+  bool videoInfoIsRepeat = false;
+  if (aNewMediaInfo.HasVideo()) {
+    if (!mVideoTracks.mLastInfo) {
+      // There is no old video info, so this can't be a repeat.
+      return false;
+    }
+    videoInfoIsRepeat =
+        *mVideoTracks.mLastInfo->GetAsVideoInfo() == aNewMediaInfo.mVideo;
+    if (!aNewMediaInfo.HasAudio()) {
+      // Only have video.
+      return videoInfoIsRepeat;
+    }
+  }
+
+  if (audioInfoIsRepeat && videoInfoIsRepeat) {
+    MOZ_DIAGNOSTIC_ASSERT(
+        aNewMediaInfo.HasVideo() && aNewMediaInfo.HasAudio(),
+        "This should only be reachable if audio and video are present");
+    // Video + audio are present and both have the same init data.
+    return true;
+  }
+
+  return false;
+}
+
+void TrackBuffersManager::OnDemuxerInitDone(const MediaResult& aResult) {
+  mTaskQueueCapability->AssertOnCurrentThread();
+  MOZ_DIAGNOSTIC_ASSERT(mInputDemuxer, "mInputDemuxer has been destroyed");
+  AUTO_PROFILER_LABEL("TrackBuffersManager::OnDemuxerInitDone", MEDIA_PLAYBACK);
+
+  mDemuxerInitRequest.Complete();
+
+  if (NS_FAILED(aResult) && StaticPrefs::media_playback_warnings_as_errors()) {
+    RejectAppend(aResult, __func__);
+    return;
+  }
+
+  MediaInfo info;
+
+  uint32_t numVideos = mInputDemuxer->GetNumberTracks(TrackInfo::kVideoTrack);
+  if (numVideos) {
+    // We currently only handle the first video track.
+    mVideoTracks.mDemuxer =
+        mInputDemuxer->GetTrackDemuxer(TrackInfo::kVideoTrack, 0);
+    MOZ_ASSERT(mVideoTracks.mDemuxer);
+    DDLINKCHILD("video demuxer", mVideoTracks.mDemuxer.get());
+    info.mVideo = *mVideoTracks.mDemuxer->GetInfo()->GetAsVideoInfo();
+    info.mVideo.mTrackId = 2;
+  }
+
+  uint32_t numAudios = mInputDemuxer->GetNumberTracks(TrackInfo::kAudioTrack);
+  if (numAudios) {
+    // We currently only handle the first audio track.
+    mAudioTracks.mDemuxer =
+        mInputDemuxer->GetTrackDemuxer(TrackInfo::kAudioTrack, 0);
+    MOZ_ASSERT(mAudioTracks.mDemuxer);
+    DDLINKCHILD("audio demuxer", mAudioTracks.mDemuxer.get());
+    info.mAudio = *mAudioTracks.mDemuxer->GetInfo()->GetAsAudioInfo();
+    info.mAudio.mTrackId = 1;
+  }
+
+  int64_t videoDuration =
+      numVideos ? info.mVideo.mDuration.ToMicroseconds() : 0;
+  int64_t audioDuration =
+      numAudios ? info.mAudio.mDuration.ToMicroseconds() : 0;
+
+  int64_t duration = std::max(videoDuration, audioDuration);
+  // 1. Update the duration attribute if it currently equals NaN.
+  // Those steps are performed by the MediaSourceDecoder::SetInitialDuration
+  mAbstractMainThread->Dispatch(NewRunnableMethod<int64_t>(
+      "MediaSourceDecoder::SetInitialDuration", mParentDecoder.get(),
+      &MediaSourceDecoder::SetInitialDuration, duration ? duration : -1));
+
+  // 2. If the initialization segment has no audio, video, or text tracks, then
+  // run the append error algorithm with the decode error parameter set to true
+  // and abort these steps.
+  if (!numVideos && !numAudios) {
+    RejectAppend(NS_ERROR_FAILURE, __func__);
+    return;
+  }
+
+  // 3. If the first initialization segment received flag is true, then run the
+  // following steps:
+  if (mFirstInitializationSegmentReceived) {
+    if (numVideos != mVideoTracks.mNumTracks ||
+        numAudios != mAudioTracks.mNumTracks) {
+      RejectAppend(NS_ERROR_FAILURE, __func__);
+      return;
+    }
+    // 1. If more than one track for a single type are present (ie 2 audio
+    // tracks), then the Track IDs match the ones in the first initialization
+    // segment.
+    // TODO
+    // 2. Add the appropriate track descriptions from this initialization
+    // segment to each of the track buffers.
+    // TODO
+    // 3. Set the need random access point flag on all track buffers to true.
+    mVideoTracks.mNeedRandomAccessPoint = true;
+    mAudioTracks.mNeedRandomAccessPoint = true;
+  }
+
+  // Check if we've received the same init data again. Some streams will
+  // resend the same data. In these cases we don't need to change the stream
+  // id as it's the same stream. Doing so would recreate decoders, possibly
+  // leading to gaps in audio and/or video (see bug 1450952).
+  bool isRepeatInitData = IsRepeatInitData(info);
+
+  MOZ_ASSERT(mFirstInitializationSegmentReceived || !isRepeatInitData,
+             "Should never detect repeat init data for first segment!");
+
+  // If we have new init data we configure and set track info as needed. If we
+  // have repeat init data we carry forward our existing track info.
+  if (!isRepeatInitData) {
+    // Increase our stream id.
+    uint32_t streamID = sStreamSourceID++;
+
+    // 4. Let active track flag equal false.
+    bool activeTrack = false;
+
+    // 5. If the first initialization segment received flag is false, then run
+    // the following steps:
+    if (!mFirstInitializationSegmentReceived) {
+      MSE_DEBUG("Get first init data");
+      mAudioTracks.mNumTracks = numAudios;
+      // TODO:
+      // 1. If the initialization segment contains tracks with codecs the user
+      // agent does not support, then run the append error algorithm with the
+      // decode error parameter set to true and abort these steps.
+
+      // 2. For each audio track in the initialization segment, run following
+      // steps: for (uint32_t i = 0; i < numAudios; i++) {
+      if (numAudios) {
+        // 1. Let audio byte stream track ID be the Track ID for the current
+        // track being processed.
+        // 2. Let audio language be a BCP 47 language tag for the language
+        // specified in the initialization segment for this track or an empty
+        // string if no language info is present.
+        // 3. If audio language equals an empty string or the 'und' BCP 47
+        // value, then run the default track language algorithm with
+        // byteStreamTrackID set to audio byte stream track ID and type set to
+        // "audio" and assign the value returned by the algorithm to audio
+        // language.
+        // 4. Let audio label be a label specified in the initialization segment
+        // for this track or an empty string if no label info is present.
+        // 5. If audio label equals an empty string, then run the default track
+        // label algorithm with byteStreamTrackID set to audio byte stream track
+        // ID and type set to "audio" and assign the value returned by the
+        // algorithm to audio label.
+        // 6. Let audio kinds be an array of kind strings specified in the
+        // initialization segment for this track or an empty array if no kind
+        // information is provided.
+        // 7. If audio kinds equals an empty array, then run the default track
+        // kinds algorithm with byteStreamTrackID set to audio byte stream track
+        // ID and type set to "audio" and assign the value returned by the
+        // algorithm to audio kinds.
+        // 8. For each value in audio kinds, run the following steps:
+        //   1. Let current audio kind equal the value from audio kinds for this
+        //   iteration of the loop.
+        //   2. Let new audio track be a new AudioTrack object.
+        //   3. Generate a unique ID and assign it to the id property on new
+        //   audio track.
+        //   4. Assign audio language to the language property on new audio
+        //   track.
+        //   5. Assign audio label to the label property on new audio track.
+        //   6. Assign current audio kind to the kind property on new audio
+        //   track.
+        //   7. If audioTracks.length equals 0, then run the following steps:
+        //     1. Set the enabled property on new audio track to true.
+        //     2. Set active track flag to true.
+        activeTrack = true;
+        //   8. Add new audio track to the audioTracks attribute on this
+        //   SourceBuffer object.
+        //   9. Queue a task to fire a trusted event named addtrack, that does
+        //   not bubble and is not cancelable, and that uses the TrackEvent
+        //   interface, at the AudioTrackList object referenced by the
+        //   audioTracks attribute on this SourceBuffer object.
+        //   10. Add new audio track to the audioTracks attribute on the
+        //   HTMLMediaElement.
+        //   11. Queue a task to fire a trusted event named addtrack, that does
+        //   not bubble and is not cancelable, and that uses the TrackEvent
+        //   interface, at the AudioTrackList object referenced by the
+        //   audioTracks attribute on the HTMLMediaElement.
+        mAudioTracks.mBuffers.AppendElement(TrackBuffer());
+        // 10. Add the track description for this track to the track buffer.
+        mAudioTracks.mInfo = new TrackInfoSharedPtr(info.mAudio, streamID);
+        mAudioTracks.mLastInfo = mAudioTracks.mInfo;
+      }
+
+      mVideoTracks.mNumTracks = numVideos;
+      // 3. For each video track in the initialization segment, run following
+      // steps: for (uint32_t i = 0; i < numVideos; i++) {
+      if (numVideos) {
+        // 1. Let video byte stream track ID be the Track ID for the current
+        // track being processed.
+        // 2. Let video language be a BCP 47 language tag for the language
+        // specified in the initialization segment for this track or an empty
+        // string if no language info is present.
+        // 3. If video language equals an empty string or the 'und' BCP 47
+        // value, then run the default track language algorithm with
+        // byteStreamTrackID set to video byte stream track ID and type set to
+        // "video" and assign the value returned by the algorithm to video
+        // language.
+        // 4. Let video label be a label specified in the initialization segment
+        // for this track or an empty string if no label info is present.
+        // 5. If video label equals an empty string, then run the default track
+        // label algorithm with byteStreamTrackID set to video byte stream track
+        // ID and type set to "video" and assign the value returned by the
+        // algorithm to video label.
+        // 6. Let video kinds be an array of kind strings specified in the
+        // initialization segment for this track or an empty array if no kind
+        // information is provided.
+        // 7. If video kinds equals an empty array, then run the default track
+        // kinds algorithm with byteStreamTrackID set to video byte stream track
+        // ID and type set to "video" and assign the value returned by the
+        // algorithm to video kinds.
+        // 8. For each value in video kinds, run the following steps:
+        //   1. Let current video kind equal the value from video kinds for this
+        //   iteration of the loop.
+        //   2. Let new video track be a new VideoTrack object.
+        //   3. Generate a unique ID and assign it to the id property on new
+        //   video track.
+        //   4. Assign video language to the language property on new video
+        //   track.
+        //   5. Assign video label to the label property on new video track.
+        //   6. Assign current video kind to the kind property on new video
+        //   track.
+        //   7. If videoTracks.length equals 0, then run the following steps:
+        //     1. Set the selected property on new video track to true.
+        //     2. Set active track flag to true.
+        activeTrack = true;
+        //   8. Add new video track to the videoTracks attribute on this
+        //   SourceBuffer object.
+        //   9. Queue a task to fire a trusted event named addtrack, that does
+        //   not bubble and is not cancelable, and that uses the TrackEvent
+        //   interface, at the VideoTrackList object referenced by the
+        //   videoTracks attribute on this SourceBuffer object.
+        //   10. Add new video track to the videoTracks attribute on the
+        //   HTMLMediaElement.
+        //   11. Queue a task to fire a trusted event named addtrack, that does
+        //   not bubble and is not cancelable, and that uses the TrackEvent
+        //   interface, at the VideoTrackList object referenced by the
+        //   videoTracks attribute on the HTMLMediaElement.
+        mVideoTracks.mBuffers.AppendElement(TrackBuffer());
+        // 10. Add the track description for this track to the track buffer.
+        mVideoTracks.mInfo = new TrackInfoSharedPtr(info.mVideo, streamID);
+        mVideoTracks.mLastInfo = mVideoTracks.mInfo;
+      }
+      // 4. For each text track in the initialization segment, run following
+      // steps:
+      // 5. If active track flag equals true, then run the following steps:
+      // This is handled by SourceBuffer once the promise is resolved.
+      if (activeTrack) {
+        mActiveTrack = true;
+      }
+
+      // 6. Set first initialization segment received flag to true.
+      mFirstInitializationSegmentReceived = true;
+    } else {
+      MSE_DEBUG("Get new init data");
+      mAudioTracks.mLastInfo = new TrackInfoSharedPtr(info.mAudio, streamID);
+      mVideoTracks.mLastInfo = new TrackInfoSharedPtr(info.mVideo, streamID);
+    }
+
+    UniquePtr<EncryptionInfo> crypto = mInputDemuxer->GetCrypto();
+    if (crypto && crypto->IsEncrypted()) {
+      // Try and dispatch 'encrypted'. Won't go if ready state still
+      // HAVE_NOTHING.
+      for (uint32_t i = 0; i < crypto->mInitDatas.Length(); i++) {
+        nsCOMPtr<nsIRunnable> r = new DispatchKeyNeededEvent(
+            mParentDecoder, crypto->mInitDatas[i].mInitData,
+            crypto->mInitDatas[i].mType);
+        mAbstractMainThread->Dispatch(r.forget());
+      }
+      info.mCrypto = *crypto;
+      // We clear our crypto init data array, so the MediaFormatReader will
+      // not emit an encrypted event for the same init data again.
+      info.mCrypto.mInitDatas.Clear();
+    }
+
+    {
+      MutexAutoLock mut(mMutex);
+      mInfo = info;
+    }
+  }
+  // We now have a valid init data ; we can store it for later use.
+  mInitData = mParser->InitData();
+
+  // We have now completed the changeType operation.
+  mChangeTypeReceived = false;
+
+  // 3. Remove the initialization segment bytes from the beginning of the input
+  // buffer. This step has already been done in InitializationSegmentReceived
+  // when we transferred the content into mCurrentInputBuffer.
+  mCurrentInputBuffer->EvictAll();
+  mInputDemuxer->NotifyDataRemoved();
+  RecreateParser(true);
+
+  // 4. Set append state to WAITING_FOR_SEGMENT.
+  SetAppendState(AppendState::WAITING_FOR_SEGMENT);
+  // 5. Jump to the loop top step above.
+  ScheduleSegmentParserLoop();
+
+  if (aResult != NS_OK && mParentDecoder) {
+    RefPtr<TrackBuffersManager> self = this;
+    mAbstractMainThread->Dispatch(NS_NewRunnableFunction(
+        "TrackBuffersManager::OnDemuxerInitDone", [self, aResult]() {
+          if (self->mParentDecoder && self->mParentDecoder->GetOwner()) {
+            self->mParentDecoder->GetOwner()->DecodeWarning(aResult);
+          }
+        }));
+  }
+}
+
+void TrackBuffersManager::OnDemuxerInitFailed(const MediaResult& aError) {
+  mTaskQueueCapability->AssertOnCurrentThread();
+  MSE_DEBUG("");
+  MOZ_ASSERT(aError != NS_ERROR_DOM_MEDIA_WAITING_FOR_DATA);
+  mDemuxerInitRequest.Complete();
+
+  RejectAppend(aError, __func__);
+}
+
+RefPtr<TrackBuffersManager::CodedFrameProcessingPromise>
+TrackBuffersManager::CodedFrameProcessing() {
+  MOZ_ASSERT(OnTaskQueue());
+  MOZ_ASSERT(mProcessingPromise.IsEmpty());
+  AUTO_PROFILER_LABEL("TrackBuffersManager::CodedFrameProcessing",
+                      MEDIA_PLAYBACK);
+
+  MediaByteRange mediaRange = mParser->MediaSegmentRange();
+  if (mediaRange.IsEmpty()) {
+    AppendDataToCurrentInputBuffer(*mInputBuffer);
+    mInputBuffer.reset();
+  } else {
+    MOZ_ASSERT(mProcessedInput >= mInputBuffer->Length());
+    if (int64_t(mProcessedInput - mInputBuffer->Length()) > mediaRange.mEnd) {
+      // Something is not quite right with the data appended. Refuse it.
+      // This would typically happen if the previous media segment was partial
+      // yet a new complete media segment was added.
+      return CodedFrameProcessingPromise::CreateAndReject(NS_ERROR_FAILURE,
+                                                          __func__);
+    }
+    // The mediaRange is offset by the init segment position previously added.
+    uint32_t length =
+        mediaRange.mEnd - (mProcessedInput - mInputBuffer->Length());
+    if (!length) {
+      // We've completed our earlier media segment and no new data is to be
+      // processed. This happens with some containers that can't detect that a
+      // media segment is ending until a new one starts.
+      RefPtr<CodedFrameProcessingPromise> p =
+          mProcessingPromise.Ensure(__func__);
+      CompleteCodedFrameProcessing();
+      return p;
+    }
+    AppendDataToCurrentInputBuffer(mInputBuffer->To(length));
+    mInputBuffer->RemoveFront(length);
+  }
+
+  RefPtr<CodedFrameProcessingPromise> p = mProcessingPromise.Ensure(__func__);
+
+  DoDemuxVideo();
+
+  return p;
+}
+
+void TrackBuffersManager::OnDemuxFailed(TrackType aTrack,
+                                        const MediaResult& aError) {
+  MOZ_ASSERT(OnTaskQueue());
+  MSE_DEBUG("Failed to demux %s, failure:%s",
+            aTrack == TrackType::kVideoTrack ? "video" : "audio",
+            aError.ErrorName().get());
+  switch (aError.Code()) {
+    case NS_ERROR_DOM_MEDIA_END_OF_STREAM:
+    case NS_ERROR_DOM_MEDIA_WAITING_FOR_DATA:
+      if (aTrack == TrackType::kVideoTrack) {
+        DoDemuxAudio();
+      } else {
+        CompleteCodedFrameProcessing();
+      }
+      break;
+    default:
+      RejectProcessing(aError, __func__);
+      break;
+  }
+}
+
+void TrackBuffersManager::DoDemuxVideo() {
+  MOZ_ASSERT(OnTaskQueue());
+  if (!HasVideo()) {
+    DoDemuxAudio();
+    return;
+  }
+  mVideoTracks.mDemuxer->GetSamples(-1)
+      ->Then(TaskQueueFromTaskQueue(), __func__, this,
+             &TrackBuffersManager::OnVideoDemuxCompleted,
+             &TrackBuffersManager::OnVideoDemuxFailed)
+      ->Track(mVideoTracks.mDemuxRequest);
+}
+
+void TrackBuffersManager::MaybeDispatchEncryptedEvent(
+    const nsTArray<RefPtr<MediaRawData>>& aSamples) {
+  // Try and dispatch 'encrypted'. Won't go if ready state still HAVE_NOTHING.
+  for (const RefPtr<MediaRawData>& sample : aSamples) {
+    for (const nsTArray<uint8_t>& initData : sample->mCrypto.mInitDatas) {
+      nsCOMPtr<nsIRunnable> r = new DispatchKeyNeededEvent(
+          mParentDecoder, initData, sample->mCrypto.mInitDataType);
+      mAbstractMainThread->Dispatch(r.forget());
+    }
+  }
+}
+
+void TrackBuffersManager::OnVideoDemuxCompleted(
+    RefPtr<MediaTrackDemuxer::SamplesHolder> aSamples) {
+  mTaskQueueCapability->AssertOnCurrentThread();
+  MSE_DEBUG("%zu video samples demuxed", aSamples->GetSamples().Length());
+  mVideoTracks.mDemuxRequest.Complete();
+  mVideoTracks.mQueuedSamples.AppendElements(aSamples->GetSamples());
+
+  MaybeDispatchEncryptedEvent(aSamples->GetSamples());
+  DoDemuxAudio();
+}
+
+void TrackBuffersManager::DoDemuxAudio() {
+  MOZ_ASSERT(OnTaskQueue());
+  if (!HasAudio()) {
+    CompleteCodedFrameProcessing();
+    return;
+  }
+  mAudioTracks.mDemuxer->GetSamples(-1)
+      ->Then(TaskQueueFromTaskQueue(), __func__, this,
+             &TrackBuffersManager::OnAudioDemuxCompleted,
+             &TrackBuffersManager::OnAudioDemuxFailed)
+      ->Track(mAudioTracks.mDemuxRequest);
+}
+
+void TrackBuffersManager::OnAudioDemuxCompleted(
+    RefPtr<MediaTrackDemuxer::SamplesHolder> aSamples) {
+  mTaskQueueCapability->AssertOnCurrentThread();
+  MSE_DEBUG("%zu audio samples demuxed", aSamples->GetSamples().Length());
+  mAudioTracks.mDemuxRequest.Complete();
+  mAudioTracks.mQueuedSamples.AppendElements(aSamples->GetSamples());
+  CompleteCodedFrameProcessing();
+
+  MaybeDispatchEncryptedEvent(aSamples->GetSamples());
+}
+
+void TrackBuffersManager::CompleteCodedFrameProcessing() {
+  MOZ_ASSERT(OnTaskQueue());
+  AUTO_PROFILER_LABEL("TrackBuffersManager::CompleteCodedFrameProcessing",
+                      MEDIA_PLAYBACK);
+
+  // 1. For each coded frame in the media segment run the following steps:
+  // Coded Frame Processing steps 1.1 to 1.21.
+
+  if (mSourceBufferAttributes->GetAppendMode() ==
+          SourceBufferAppendMode::Sequence &&
+      mVideoTracks.mQueuedSamples.Length() &&
+      mAudioTracks.mQueuedSamples.Length()) {
+    // When we are in sequence mode, the order in which we process the frames is
+    // important as it determines the future value of timestampOffset.
+    // So we process the earliest sample first. See bug 1293576.
+    TimeInterval videoInterval =
+        PresentationInterval(mVideoTracks.mQueuedSamples);
+    TimeInterval audioInterval =
+        PresentationInterval(mAudioTracks.mQueuedSamples);
+    if (audioInterval.mStart < videoInterval.mStart) {
+      ProcessFrames(mAudioTracks.mQueuedSamples, mAudioTracks);
+      ProcessFrames(mVideoTracks.mQueuedSamples, mVideoTracks);
+    } else {
+      ProcessFrames(mVideoTracks.mQueuedSamples, mVideoTracks);
+      ProcessFrames(mAudioTracks.mQueuedSamples, mAudioTracks);
+    }
+  } else {
+    ProcessFrames(mVideoTracks.mQueuedSamples, mVideoTracks);
+    ProcessFrames(mAudioTracks.mQueuedSamples, mAudioTracks);
+  }
+
+#if defined(DEBUG)
+  if (HasVideo()) {
+    const auto& track = mVideoTracks.GetTrackBuffer();
+    MOZ_ASSERT(track.IsEmpty() || track[0]->mKeyframe);
+    for (uint32_t i = 1; i < track.Length(); i++) {
+      MOZ_ASSERT(
+          (track[i - 1]->mTrackInfo->GetID() == track[i]->mTrackInfo->GetID() &&
+           track[i - 1]->mTimecode <= track[i]->mTimecode) ||
+          track[i]->mKeyframe);
+    }
+  }
+  if (HasAudio()) {
+    const auto& track = mAudioTracks.GetTrackBuffer();
+    MOZ_ASSERT(track.IsEmpty() || track[0]->mKeyframe);
+    for (uint32_t i = 1; i < track.Length(); i++) {
+      MOZ_ASSERT(
+          (track[i - 1]->mTrackInfo->GetID() == track[i]->mTrackInfo->GetID() &&
+           track[i - 1]->mTimecode <= track[i]->mTimecode) ||
+          track[i]->mKeyframe);
+    }
+  }
+#endif
+
+  mVideoTracks.mQueuedSamples.Clear();
+  mAudioTracks.mQueuedSamples.Clear();
+
+  UpdateBufferedRanges();
+
+  // Update our reported total size.
+  mSizeSourceBuffer = mVideoTracks.mSizeBuffer + mAudioTracks.mSizeBuffer;
+
+  // Return to step 6.4 of Segment Parser Loop algorithm
+  // 4. If this SourceBuffer is full and cannot accept more media data, then set
+  // the buffer full flag to true.
+  if (mSizeSourceBuffer >= EvictionThreshold()) {
+    mBufferFull = true;
+  }
+
+  // 5. If the input buffer does not contain a complete media segment, then jump
+  // to the need more data step below.
+  if (mParser->MediaSegmentRange().IsEmpty()) {
+    ResolveProcessing(true, __func__);
+    return;
+  }
+
+  mLastParsedEndTime = Some(std::max(mAudioTracks.mLastParsedEndTime,
+                                     mVideoTracks.mLastParsedEndTime));
+
+  // 6. Remove the media segment bytes from the beginning of the input buffer.
+  // Clear our demuxer from any already processed data.
+  int64_t safeToEvict =
+      std::min(HasVideo() ? mVideoTracks.mDemuxer->GetEvictionOffset(
+                                mVideoTracks.mLastParsedEndTime)
+                          : INT64_MAX,
+               HasAudio() ? mAudioTracks.mDemuxer->GetEvictionOffset(
+                                mAudioTracks.mLastParsedEndTime)
+                          : INT64_MAX);
+  mCurrentInputBuffer->EvictBefore(safeToEvict);
+
+  mInputDemuxer->NotifyDataRemoved();
+  RecreateParser(true);
+
+  // 7. Set append state to WAITING_FOR_SEGMENT.
+  SetAppendState(AppendState::WAITING_FOR_SEGMENT);
+
+  // 8. Jump to the loop top step above.
+  ResolveProcessing(false, __func__);
+}
+
+void TrackBuffersManager::RejectProcessing(const MediaResult& aRejectValue,
+                                           const char* aName) {
+  mProcessingPromise.RejectIfExists(aRejectValue, __func__);
+}
+
+void TrackBuffersManager::ResolveProcessing(bool aResolveValue,
+                                            const char* aName) {
+  mProcessingPromise.ResolveIfExists(aResolveValue, __func__);
+}
+
+void TrackBuffersManager::CheckSequenceDiscontinuity(
+    const TimeUnit& aPresentationTime) {
+  if (mSourceBufferAttributes->GetAppendMode() ==
+          SourceBufferAppendMode::Sequence &&
+      mSourceBufferAttributes->HaveGroupStartTimestamp()) {
+    mSourceBufferAttributes->SetTimestampOffset(
+        mSourceBufferAttributes->GetGroupStartTimestamp() - aPresentationTime);
+    mSourceBufferAttributes->SetGroupEndTimestamp(
+        mSourceBufferAttributes->GetGroupStartTimestamp());
+    mVideoTracks.mNeedRandomAccessPoint = true;
+    mAudioTracks.mNeedRandomAccessPoint = true;
+    mSourceBufferAttributes->ResetGroupStartTimestamp();
+  }
+}
+
+TimeInterval TrackBuffersManager::PresentationInterval(
+    const TrackBuffer& aSamples) const {
+  TimeInterval presentationInterval =
+      TimeInterval(aSamples[0]->mTime, aSamples[0]->GetEndTime());
+
+  for (uint32_t i = 1; i < aSamples.Length(); i++) {
+    auto& sample = aSamples[i];
+    presentationInterval = presentationInterval.Span(
+        TimeInterval(sample->mTime, sample->GetEndTime()));
+  }
+  return presentationInterval;
+}
+
+void TrackBuffersManager::ProcessFrames(TrackBuffer& aSamples,
+                                        TrackData& aTrackData) {
+  AUTO_PROFILER_LABEL("TrackBuffersManager::ProcessFrames", MEDIA_PLAYBACK);
+  if (!aSamples.Length()) {
+    return;
+  }
+
+  // 1. If generate timestamps flag equals true
+  // Let presentation timestamp equal 0.
+  // Otherwise
+  // Let presentation timestamp be a double precision floating point
+  // representation of the coded frame's presentation timestamp in seconds.
+  TimeUnit presentationTimestamp = mSourceBufferAttributes->mGenerateTimestamps
+                                       ? TimeUnit::Zero()
+                                       : aSamples[0]->mTime;
+
+  // 3. If mode equals "sequence" and group start timestamp is set, then run the
+  // following steps:
+  CheckSequenceDiscontinuity(presentationTimestamp);
+
+  // 5. Let track buffer equal the track buffer that the coded frame will be
+  // added to.
+  auto& trackBuffer = aTrackData;
+
+  TimeIntervals samplesRange;
+  uint32_t sizeNewSamples = 0;
+  TrackBuffer samples;  // array that will contain the frames to be added
+                        // to our track buffer.
+
+  // We assume that no frames are contiguous within a media segment and as such
+  // don't need to check for discontinuity except for the first frame and should
+  // a frame be ignored due to the target window.
+  bool needDiscontinuityCheck = true;
+
+  // Highest presentation time seen in samples block.
+  TimeUnit highestSampleTime;
+
+  if (aSamples.Length()) {
+    aTrackData.mLastParsedEndTime = TimeUnit();
+  }
+
+  auto addToSamples = [&](MediaRawData* aSample,
+                          const TimeInterval& aInterval) {
+    aSample->mTime = aInterval.mStart;
+    aSample->mDuration = aInterval.Length();
+    aSample->mTrackInfo = trackBuffer.mLastInfo;
+    MOZ_DIAGNOSTIC_ASSERT(aSample->HasValidTime());
+    samplesRange += aInterval;
+    sizeNewSamples += aSample->ComputedSizeOfIncludingThis();
+    samples.AppendElement(aSample);
+  };
+
+  // Will be set to the last frame dropped due to being outside mAppendWindow.
+  // It will be added prior the first following frame which can be added to the
+  // track buffer.
+  // This sample will be set with a duration of only 1us which will cause it to
+  // be dropped once returned by the decoder.
+  // This sample is required to "prime" the decoder so that the following frame
+  // can be fully decoded.
+  RefPtr<MediaRawData> previouslyDroppedSample;
+  for (auto& sample : aSamples) {
+    const TimeUnit sampleEndTime = sample->GetEndTime();
+    if (sampleEndTime > aTrackData.mLastParsedEndTime) {
+      aTrackData.mLastParsedEndTime = sampleEndTime;
+    }
+
+    // We perform step 10 right away as we can't do anything should a keyframe
+    // be needed until we have one.
+
+    // 10. If the need random access point flag on track buffer equals true,
+    // then run the following steps:
+    if (trackBuffer.mNeedRandomAccessPoint) {
+      // 1. If the coded frame is not a random access point, then drop the coded
+      // frame and jump to the top of the loop to start processing the next
+      // coded frame.
+      if (!sample->mKeyframe) {
+        previouslyDroppedSample = nullptr;
+        continue;
+      }
+      // 2. Set the need random access point flag on track buffer to false.
+      trackBuffer.mNeedRandomAccessPoint = false;
+    }
+
+    // We perform step 1,2 and 4 at once:
+    // 1. If generate timestamps flag equals true:
+    //   Let presentation timestamp equal 0.
+    //   Let decode timestamp equal 0.
+    // Otherwise:
+    //   Let presentation timestamp be a double precision floating point
+    //   representation of the coded frame's presentation timestamp in seconds.
+    //   Let decode timestamp be a double precision floating point
+    //   representation of the coded frame's decode timestamp in seconds.
+
+    // 2. Let frame duration be a double precision floating point representation
+    // of the coded frame's duration in seconds. Step 3 is performed earlier or
+    // when a discontinuity has been detected.
+    // 4. If timestampOffset is not 0, then run the following steps:
+
+    TimeUnit sampleTime = sample->mTime;
+    TimeUnit sampleTimecode = sample->mTimecode;
+    TimeUnit sampleDuration = sample->mDuration;
+    TimeUnit timestampOffset = mSourceBufferAttributes->GetTimestampOffset();
+
+    TimeInterval sampleInterval =
+        mSourceBufferAttributes->mGenerateTimestamps
+            ? TimeInterval(timestampOffset, timestampOffset + sampleDuration)
+            : TimeInterval(timestampOffset + sampleTime,
+                           timestampOffset + sampleTime + sampleDuration);
+    TimeUnit decodeTimestamp = mSourceBufferAttributes->mGenerateTimestamps
+                                   ? timestampOffset
+                                   : timestampOffset + sampleTimecode;
+
+    SAMPLE_DEBUG(
+        "Processing %s frame [%" PRId64 ",%" PRId64 "] (adjusted:[%" PRId64
+        ",%" PRId64 "]), dts:%" PRId64 ", duration:%" PRId64 ", kf:%d)",
+        aTrackData.mInfo->mMimeType.get(), sample->mTime.ToMicroseconds(),
+        sample->GetEndTime().ToMicroseconds(),
+        sampleInterval.mStart.ToMicroseconds(),
+        sampleInterval.mEnd.ToMicroseconds(),
+        sample->mTimecode.ToMicroseconds(), sample->mDuration.ToMicroseconds(),
+        sample->mKeyframe);
+
+    // 6. If last decode timestamp for track buffer is set and decode timestamp
+    // is less than last decode timestamp: OR If last decode timestamp for track
+    // buffer is set and the difference between decode timestamp and last decode
+    // timestamp is greater than 2 times last frame duration:
+
+    if (needDiscontinuityCheck && trackBuffer.mLastDecodeTimestamp.isSome() &&
+        (decodeTimestamp < trackBuffer.mLastDecodeTimestamp.ref() ||
+         (decodeTimestamp - trackBuffer.mLastDecodeTimestamp.ref() >
+          trackBuffer.mLongestFrameDuration * 2))) {
+      MSE_DEBUG("Discontinuity detected.");
+      SourceBufferAppendMode appendMode =
+          mSourceBufferAttributes->GetAppendMode();
+
+      // 1a. If mode equals "segments":
+      if (appendMode == SourceBufferAppendMode::Segments) {
+        // Set group end timestamp to presentation timestamp.
+        mSourceBufferAttributes->SetGroupEndTimestamp(sampleInterval.mStart);
+      }
+      // 1b. If mode equals "sequence":
+      if (appendMode == SourceBufferAppendMode::Sequence) {
+        // Set group start timestamp equal to the group end timestamp.
+        mSourceBufferAttributes->SetGroupStartTimestamp(
+            mSourceBufferAttributes->GetGroupEndTimestamp());
+      }
+      for (auto& track : GetTracksList()) {
+        // 2. Unset the last decode timestamp on all track buffers.
+        // 3. Unset the last frame duration on all track buffers.
+        // 4. Unset the highest end timestamp on all track buffers.
+        // 5. Set the need random access point flag on all track buffers to
+        // true.
+        track->ResetAppendState();
+      }
+      // 6. Jump to the Loop Top step above to restart processing of the current
+      // coded frame. Rather that restarting the process for the frame, we run
+      // the first steps again instead.
+      // 3. If mode equals "sequence" and group start timestamp is set, then run
+      // the following steps:
+      TimeUnit presentationTimestamp =
+          mSourceBufferAttributes->mGenerateTimestamps ? TimeUnit()
+                                                       : sampleTime;
+      CheckSequenceDiscontinuity(presentationTimestamp);
+
+      if (!sample->mKeyframe) {
+        previouslyDroppedSample = nullptr;
+        continue;
+      }
+      if (appendMode == SourceBufferAppendMode::Sequence) {
+        // mSourceBufferAttributes->GetTimestampOffset() was modified during
+        // CheckSequenceDiscontinuity. We need to update our variables.
+        timestampOffset = mSourceBufferAttributes->GetTimestampOffset();
+        sampleInterval =
+            mSourceBufferAttributes->mGenerateTimestamps
+                ? TimeInterval(timestampOffset,
+                               timestampOffset + sampleDuration)
+                : TimeInterval(timestampOffset + sampleTime,
+                               timestampOffset + sampleTime + sampleDuration);
+        decodeTimestamp = mSourceBufferAttributes->mGenerateTimestamps
+                              ? timestampOffset
+                              : timestampOffset + sampleTimecode;
+      }
+      trackBuffer.mNeedRandomAccessPoint = false;
+      needDiscontinuityCheck = false;
+    }
+
+    // 7. Let frame end timestamp equal the sum of presentation timestamp and
+    // frame duration. This is sampleInterval.mEnd
+
+    // 8. If presentation timestamp is less than appendWindowStart, then set the
+    // need random access point flag to true, drop the coded frame, and jump to
+    // the top of the loop to start processing the next coded frame.
+    // 9. If frame end timestamp is greater than appendWindowEnd, then set the
+    // need random access point flag to true, drop the coded frame, and jump to
+    // the top of the loop to start processing the next coded frame.
+    if (!mAppendWindow.ContainsStrict(sampleInterval)) {
+      if (mAppendWindow.IntersectsStrict(sampleInterval)) {
+        // 8. Note: Some implementations MAY choose to collect some of these
+        //    coded frames with presentation timestamp less than
+        //    appendWindowStart and use them to generate a splice at the first
+        //    coded frame that has a presentation timestamp greater than or
+        //    equal to appendWindowStart even if that frame is not a random
+        //    access point. Supporting this requires multiple decoders or faster
+        //    than real-time decoding so for now this behavior will not be a
+        //    normative requirement.
+        // 9. Note: Some implementations MAY choose to collect coded frames with
+        //    presentation timestamp less than appendWindowEnd and frame end
+        //    timestamp greater than appendWindowEnd and use them to generate a
+        //    splice across the portion of the collected coded frames within the
+        //    append window at time of collection, and the beginning portion of
+        //    later processed frames which only partially overlap the end of the
+        //    collected coded frames. Supporting this requires multiple decoders
+        //    or faster than real-time decoding so for now this behavior will
+        //    not be a normative requirement. In conjunction with collecting
+        //    coded frames that span appendWindowStart, implementations MAY thus
+        //    support gapless audio splicing.
+        TimeInterval intersection = mAppendWindow.Intersection(sampleInterval);
+        sample->mOriginalPresentationWindow = Some(sampleInterval);
+        MSE_DEBUGV("will truncate frame from [%" PRId64 ",%" PRId64
+                   "] to [%" PRId64 ",%" PRId64 "]",
+                   sampleInterval.mStart.ToMicroseconds(),
+                   sampleInterval.mEnd.ToMicroseconds(),
+                   intersection.mStart.ToMicroseconds(),
+                   intersection.mEnd.ToMicroseconds());
+        sampleInterval = intersection;
+      } else {
+        sample->mOriginalPresentationWindow = Some(sampleInterval);
+        sample->mTimecode = decodeTimestamp;
+        previouslyDroppedSample = sample;
+        MSE_DEBUGV("frame [%" PRId64 ",%" PRId64
+                   "] outside appendWindow [%" PRId64 ",%" PRId64 "] dropping",
+                   sampleInterval.mStart.ToMicroseconds(),
+                   sampleInterval.mEnd.ToMicroseconds(),
+                   mAppendWindow.mStart.ToMicroseconds(),
+                   mAppendWindow.mEnd.ToMicroseconds());
+        if (samples.Length()) {
+          // We are creating a discontinuity in the samples.
+          // Insert the samples processed so far.
+          InsertFrames(samples, samplesRange, trackBuffer);
+          samples.Clear();
+          samplesRange = TimeIntervals();
+          trackBuffer.mSizeBuffer += sizeNewSamples;
+          sizeNewSamples = 0;
+          UpdateHighestTimestamp(trackBuffer, highestSampleTime);
+        }
+        trackBuffer.mNeedRandomAccessPoint = true;
+        needDiscontinuityCheck = true;
+        continue;
+      }
+    }
+    if (previouslyDroppedSample) {
+      MSE_DEBUGV("Adding silent frame");
+      // This "silent" sample will be added so that it starts exactly before the
+      // first usable one. The duration of the actual sample will be adjusted so
+      // that the total duration staty the same.
+      // Setting a dummy presentation window of 1us will cause this sample to be
+      // dropped after decoding by the AudioTrimmer (if audio).
+      TimeInterval previouslyDroppedSampleInterval =
+          TimeInterval(sampleInterval.mStart,
+                       sampleInterval.mStart + TimeUnit::FromMicroseconds(1));
+      addToSamples(previouslyDroppedSample, previouslyDroppedSampleInterval);
+      previouslyDroppedSample = nullptr;
+      sampleInterval.mStart += previouslyDroppedSampleInterval.Length();
+    }
+
+    sample->mTimecode = decodeTimestamp;
+    addToSamples(sample, sampleInterval);
+
+    // Steps 11,12,13,14, 15 and 16 will be done in one block in InsertFrames.
+
+    trackBuffer.mLongestFrameDuration =
+        trackBuffer.mLastFrameDuration.isSome()
+            ? sample->mKeyframe
+                  ? sampleDuration
+                  : std::max(sampleDuration, trackBuffer.mLongestFrameDuration)
+            : sampleDuration;
+
+    // 17. Set last decode timestamp for track buffer to decode timestamp.
+    trackBuffer.mLastDecodeTimestamp = Some(decodeTimestamp);
+    // 18. Set last frame duration for track buffer to frame duration.
+    trackBuffer.mLastFrameDuration = Some(sampleDuration);
+
+    // 19. If highest end timestamp for track buffer is unset or frame end
+    // timestamp is greater than highest end timestamp, then set highest end
+    // timestamp for track buffer to frame end timestamp.
+    if (trackBuffer.mHighestEndTimestamp.isNothing() ||
+        sampleInterval.mEnd > trackBuffer.mHighestEndTimestamp.ref()) {
+      trackBuffer.mHighestEndTimestamp = Some(sampleInterval.mEnd);
+    }
+    if (sampleInterval.mStart > highestSampleTime) {
+      highestSampleTime = sampleInterval.mStart;
+    }
+    // 20. If frame end timestamp is greater than group end timestamp, then set
+    // group end timestamp equal to frame end timestamp.
+    if (sampleInterval.mEnd > mSourceBufferAttributes->GetGroupEndTimestamp()) {
+      mSourceBufferAttributes->SetGroupEndTimestamp(sampleInterval.mEnd);
+    }
+    // 21. If generate timestamps flag equals true, then set timestampOffset
+    // equal to frame end timestamp.
+    if (mSourceBufferAttributes->mGenerateTimestamps) {
+      mSourceBufferAttributes->SetTimestampOffset(sampleInterval.mEnd);
+    }
+  }
+
+  if (samples.Length()) {
+    InsertFrames(samples, samplesRange, trackBuffer);
+    trackBuffer.mSizeBuffer += sizeNewSamples;
+    UpdateHighestTimestamp(trackBuffer, highestSampleTime);
+  }
+}
+
+bool TrackBuffersManager::CheckNextInsertionIndex(TrackData& aTrackData,
+                                                  const TimeUnit& aSampleTime) {
+  if (aTrackData.mNextInsertionIndex.isSome()) {
+    return true;
+  }
+
+  const TrackBuffer& data = aTrackData.GetTrackBuffer();
+
+  if (data.IsEmpty() || aSampleTime < aTrackData.mBufferedRanges.GetStart()) {
+    aTrackData.mNextInsertionIndex = Some(0u);
+    return true;
+  }
+
+  // Find which discontinuity we should insert the frame before.
+  TimeInterval target;
+  for (const auto& interval : aTrackData.mBufferedRanges) {
+    if (aSampleTime < interval.mStart) {
+      target = interval;
+      break;
+    }
+  }
+  if (target.IsEmpty()) {
+    // No target found, it will be added at the end of the track buffer.
+    aTrackData.mNextInsertionIndex = Some(uint32_t(data.Length()));
+    return true;
+  }
+  // We now need to find the first frame of the searched interval.
+  // We will insert our new frames right before.
+  for (uint32_t i = 0; i < data.Length(); i++) {
+    const RefPtr<MediaRawData>& sample = data[i];
+    if (sample->mTime >= target.mStart ||
+        sample->GetEndTime() > target.mStart) {
+      aTrackData.mNextInsertionIndex = Some(i);
+      return true;
+    }
+  }
+  NS_ASSERTION(false, "Insertion Index Not Found");
+  return false;
+}
+
+void TrackBuffersManager::InsertFrames(TrackBuffer& aSamples,
+                                       const TimeIntervals& aIntervals,
+                                       TrackData& aTrackData) {
+  AUTO_PROFILER_LABEL("TrackBuffersManager::InsertFrames", MEDIA_PLAYBACK);
+  // 5. Let track buffer equal the track buffer that the coded frame will be
+  // added to.
+  auto& trackBuffer = aTrackData;
+
+  MSE_DEBUGV("Processing %zu %s frames(start:%" PRId64 " end:%" PRId64 ")",
+             aSamples.Length(), aTrackData.mInfo->mMimeType.get(),
+             aIntervals.GetStart().ToMicroseconds(),
+             aIntervals.GetEnd().ToMicroseconds());
+  if (profiler_thread_is_being_profiled_for_markers()) {
+    nsPrintfCString markerString(
+        "Processing %zu %s frames(start:%" PRId64 " end:%" PRId64 ")",
+        aSamples.Length(), aTrackData.mInfo->mMimeType.get(),
+        aIntervals.GetStart().ToMicroseconds(),
+        aIntervals.GetEnd().ToMicroseconds());
+    PROFILER_MARKER_TEXT("InsertFrames", MEDIA_PLAYBACK, {}, markerString);
+  }
+
+  // 11. Let spliced audio frame be an unset variable for holding audio splice
+  // information
+  // 12. Let spliced timed text frame be an unset variable for holding timed
+  // text splice information
+
+  // 13. If last decode timestamp for track buffer is unset and presentation
+  // timestamp falls within the presentation interval of a coded frame in track
+  // buffer,then run the following steps: For now we only handle replacing
+  // existing frames with the new ones. So we skip this step.
+
+  // 14. Remove existing coded frames in track buffer:
+  //   a) If highest end timestamp for track buffer is not set:
+  //      Remove all coded frames from track buffer that have a presentation
+  //      timestamp greater than or equal to presentation timestamp and less
+  //      than frame end timestamp.
+  //   b) If highest end timestamp for track buffer is set and less than or
+  //   equal to presentation timestamp:
+  //      Remove all coded frames from track buffer that have a presentation
+  //      timestamp greater than or equal to highest end timestamp and less than
+  //      frame end timestamp
+
+  // There is an ambiguity on how to remove frames, which was lodged with:
+  // https://www.w3.org/Bugs/Public/show_bug.cgi?id=28710, implementing as per
+  // bug description.
+
+  // 15. Remove decoding dependencies of the coded frames removed in the
+  // previous step: Remove all coded frames between the coded frames removed in
+  // the previous step and the next random access point after those removed
+  // frames.
+
+  if (trackBuffer.mBufferedRanges.IntersectsStrict(aIntervals)) {
+    if (aSamples[0]->mKeyframe &&
+        (mType.Type() == MEDIAMIMETYPE("video/webm") ||
+         mType.Type() == MEDIAMIMETYPE("audio/webm"))) {
+      // We are starting a new GOP, we do not have to worry about breaking an
+      // existing current coded frame group. Reset the next insertion index
+      // so the search for when to start our frames removal can be exhaustive.
+      // This is a workaround for bug 1276184 and only until either bug 1277733
+      // or bug 1209386 is fixed.
+      // With the webm container, we can't always properly determine the
+      // duration of the last frame, which may cause the last frame of a cluster
+      // to overlap the following frame.
+      trackBuffer.mNextInsertionIndex.reset();
+    }
+    uint32_t index = RemoveFrames(aIntervals, trackBuffer,
+                                  trackBuffer.mNextInsertionIndex.refOr(0),
+                                  RemovalMode::kTruncateFrame);
+    if (index) {
+      trackBuffer.mNextInsertionIndex = Some(index);
+    }
+  }
+
+  // 16. Add the coded frame with the presentation timestamp, decode timestamp,
+  // and frame duration to the track buffer.
+  if (!CheckNextInsertionIndex(aTrackData, aSamples[0]->mTime)) {
+    RejectProcessing(NS_ERROR_FAILURE, __func__);
+    return;
+  }
+
+  // Adjust our demuxing index if necessary.
+  if (trackBuffer.mNextGetSampleIndex.isSome()) {
+    if (trackBuffer.mNextInsertionIndex.ref() ==
+            trackBuffer.mNextGetSampleIndex.ref() &&
+        aIntervals.GetEnd() >= trackBuffer.mNextSampleTime) {
+      MSE_DEBUG("Next sample to be played got overwritten");
+      trackBuffer.mNextGetSampleIndex.reset();
+      ResetEvictionIndex(trackBuffer);
+    } else if (trackBuffer.mNextInsertionIndex.ref() <=
+               trackBuffer.mNextGetSampleIndex.ref()) {
+      trackBuffer.mNextGetSampleIndex.ref() += aSamples.Length();
+      // We could adjust the eviction index so that the new data gets added to
+      // the evictable amount (as it is prior currentTime). However, considering
+      // new data is being added prior the current playback, it's likely that
+      // this data will be played next, and as such we probably don't want to
+      // have it evicted too early. So instead reset the eviction index instead.
+      ResetEvictionIndex(trackBuffer);
+    }
+  }
+
+  TrackBuffer& data = trackBuffer.GetTrackBuffer();
+  data.InsertElementsAt(trackBuffer.mNextInsertionIndex.ref(), aSamples);
+  trackBuffer.mNextInsertionIndex.ref() += aSamples.Length();
+
+  // Update our buffered range with new sample interval.
+  trackBuffer.mBufferedRanges += aIntervals;
+  // We allow a fuzz factor in our interval of half a frame length,
+  // as fuzz is +/- value, giving an effective leeway of a full frame
+  // length.
+  if (!aIntervals.IsEmpty()) {
+    TimeIntervals range(aIntervals);
+    range.SetFuzz(trackBuffer.mLongestFrameDuration / 2);
+    trackBuffer.mSanitizedBufferedRanges += range;
+  }
+}
+
+void TrackBuffersManager::UpdateHighestTimestamp(
+    TrackData& aTrackData, const media::TimeUnit& aHighestTime) {
+  if (aHighestTime > aTrackData.mHighestStartTimestamp) {
+    MutexAutoLock mut(mMutex);
+    aTrackData.mHighestStartTimestamp = aHighestTime;
+  }
+}
+
+uint32_t TrackBuffersManager::RemoveFrames(const TimeIntervals& aIntervals,
+                                           TrackData& aTrackData,
+                                           uint32_t aStartIndex,
+                                           RemovalMode aMode) {
+  AUTO_PROFILER_LABEL("TrackBuffersManager::RemoveFrames", MEDIA_PLAYBACK);
+  TrackBuffer& data = aTrackData.GetTrackBuffer();
+  Maybe<uint32_t> firstRemovedIndex;
+  uint32_t lastRemovedIndex = 0;
+
+  // We loop from aStartIndex to avoid removing frames that we inserted earlier
+  // and part of the current coded frame group. This is allows to handle step
+  // 14 of the coded frame processing algorithm without having to check the
+  // value of highest end timestamp: "Remove existing coded frames in track
+  // buffer:
+  //  If highest end timestamp for track buffer is not set:
+  //   Remove all coded frames from track buffer that have a presentation
+  //   timestamp greater than or equal to presentation timestamp and less than
+  //   frame end timestamp.
+  //  If highest end timestamp for track buffer is set and less than or equal to
+  //  presentation timestamp:
+  //   Remove all coded frames from track buffer that have a presentation
+  //   timestamp greater than or equal to highest end timestamp and less than
+  //   frame end timestamp"
+  TimeUnit intervalsEnd = aIntervals.GetEnd();
+  for (uint32_t i = aStartIndex; i < data.Length(); i++) {
+    RefPtr<MediaRawData>& sample = data[i];
+    if (aIntervals.ContainsStrict(sample->mTime)) {
+      // The start of this existing frame will be overwritten, we drop that
+      // entire frame.
+      MSE_DEBUGV("overridding start of frame [%" PRId64 ",%" PRId64
+                 "] with [%" PRId64 ",%" PRId64 "] dropping",
+                 sample->mTime.ToMicroseconds(),
+                 sample->GetEndTime().ToMicroseconds(),
+                 aIntervals.GetStart().ToMicroseconds(),
+                 aIntervals.GetEnd().ToMicroseconds());
+      if (firstRemovedIndex.isNothing()) {
+        firstRemovedIndex = Some(i);
+      }
+      lastRemovedIndex = i;
+      continue;
+    }
+    TimeInterval sampleInterval(sample->mTime, sample->GetEndTime());
+    if (aMode == RemovalMode::kTruncateFrame &&
+        aIntervals.IntersectsStrict(sampleInterval)) {
+      // The sample to be overwritten is only partially covered.
+      TimeIntervals intersection =
+          Intersection(aIntervals, TimeIntervals(sampleInterval));
+      bool found = false;
+      TimeUnit startTime = intersection.GetStart(&found);
+      MOZ_DIAGNOSTIC_ASSERT(found, "Must intersect with added coded frames");
+      Unused << found;
+      // Signal that this frame should be truncated when decoded.
+      if (!sample->mOriginalPresentationWindow) {
+        sample->mOriginalPresentationWindow = Some(sampleInterval);
+      }
+      MOZ_ASSERT(startTime > sample->mTime);
+      sample->mDuration = startTime - sample->mTime;
+      MOZ_DIAGNOSTIC_ASSERT(sample->mDuration.IsValid());
+      MSE_DEBUGV("partial overwrite of frame [%" PRId64 ",%" PRId64
+                 "] with [%" PRId64 ",%" PRId64
+                 "] trim to "
+                 "[%" PRId64 ",%" PRId64 "]",
+                 sampleInterval.mStart.ToMicroseconds(),
+                 sampleInterval.mEnd.ToMicroseconds(),
+                 aIntervals.GetStart().ToMicroseconds(),
+                 aIntervals.GetEnd().ToMicroseconds(),
+                 sample->mTime.ToMicroseconds(),
+                 sample->GetEndTime().ToMicroseconds());
+      continue;
+    }
+
+    if (sample->mTime >= intervalsEnd) {
+      // We can break the loop now. All frames up to the next keyframe will be
+      // removed during the next step.
+      break;
+    }
+  }
+
+  if (firstRemovedIndex.isNothing()) {
+    return 0;
+  }
+
+  // Remove decoding dependencies of the coded frames removed in the previous
+  // step: Remove all coded frames between the coded frames removed in the
+  // previous step and the next random access point after those removed frames.
+  for (uint32_t i = lastRemovedIndex + 1; i < data.Length(); i++) {
+    const RefPtr<MediaRawData>& sample = data[i];
+    if (sample->mKeyframe) {
+      break;
+    }
+    lastRemovedIndex = i;
+  }
+
+  TimeUnit maxSampleDuration;
+  uint32_t sizeRemoved = 0;
+  TimeIntervals removedIntervals;
+  for (uint32_t i = firstRemovedIndex.ref(); i <= lastRemovedIndex; i++) {
+    const RefPtr<MediaRawData> sample = data[i];
+    TimeInterval sampleInterval =
+        TimeInterval(sample->mTime, sample->GetEndTime());
+    removedIntervals += sampleInterval;
+    if (sample->mDuration > maxSampleDuration) {
+      maxSampleDuration = sample->mDuration;
+    }
+    sizeRemoved += sample->ComputedSizeOfIncludingThis();
+  }
+  aTrackData.mSizeBuffer -= sizeRemoved;
+
+  MSE_DEBUG("Removing frames from:%u (frames:%u) ([%f, %f))",
+            firstRemovedIndex.ref(),
+            lastRemovedIndex - firstRemovedIndex.ref() + 1,
+            removedIntervals.GetStart().ToSeconds(),
+            removedIntervals.GetEnd().ToSeconds());
+  if (profiler_thread_is_being_profiled_for_markers()) {
+    nsPrintfCString markerString(
+        "Removing frames from:%u (frames:%u) ([%f, %f))",
+        firstRemovedIndex.ref(), lastRemovedIndex - firstRemovedIndex.ref() + 1,
+        removedIntervals.GetStart().ToSeconds(),
+        removedIntervals.GetEnd().ToSeconds());
+    PROFILER_MARKER_TEXT("RemoveFrames", MEDIA_PLAYBACK, {}, markerString);
+  }
+
+  if (aTrackData.mNextGetSampleIndex.isSome()) {
+    if (aTrackData.mNextGetSampleIndex.ref() >= firstRemovedIndex.ref() &&
+        aTrackData.mNextGetSampleIndex.ref() <= lastRemovedIndex) {
+      MSE_DEBUG("Next sample to be played got evicted");
+      aTrackData.mNextGetSampleIndex.reset();
+      ResetEvictionIndex(aTrackData);
+    } else if (aTrackData.mNextGetSampleIndex.ref() > lastRemovedIndex) {
+      uint32_t samplesRemoved = lastRemovedIndex - firstRemovedIndex.ref() + 1;
+      aTrackData.mNextGetSampleIndex.ref() -= samplesRemoved;
+      if (aTrackData.mEvictionIndex.mLastIndex > lastRemovedIndex) {
+        MOZ_DIAGNOSTIC_ASSERT(
+            aTrackData.mEvictionIndex.mLastIndex >= samplesRemoved &&
+                aTrackData.mEvictionIndex.mEvictable >= sizeRemoved,
+            "Invalid eviction index");
+        MutexAutoLock mut(mMutex);
+        aTrackData.mEvictionIndex.mLastIndex -= samplesRemoved;
+        aTrackData.mEvictionIndex.mEvictable -= sizeRemoved;
+      } else {
+        ResetEvictionIndex(aTrackData);
+      }
+    }
+  }
+
+  if (aTrackData.mNextInsertionIndex.isSome()) {
+    if (aTrackData.mNextInsertionIndex.ref() > firstRemovedIndex.ref() &&
+        aTrackData.mNextInsertionIndex.ref() <= lastRemovedIndex + 1) {
+      aTrackData.ResetAppendState();
+      MSE_DEBUG("NextInsertionIndex got reset.");
+    } else if (aTrackData.mNextInsertionIndex.ref() > lastRemovedIndex + 1) {
+      aTrackData.mNextInsertionIndex.ref() -=
+          lastRemovedIndex - firstRemovedIndex.ref() + 1;
+    }
+  }
+
+  // Update our buffered range to exclude the range just removed.
+  aTrackData.mBufferedRanges -= removedIntervals;
+
+  // Recalculate sanitized buffered ranges.
+  aTrackData.mSanitizedBufferedRanges = aTrackData.mBufferedRanges;
+  aTrackData.mSanitizedBufferedRanges.SetFuzz(maxSampleDuration / 2);
+
+  data.RemoveElementsAt(firstRemovedIndex.ref(),
+                        lastRemovedIndex - firstRemovedIndex.ref() + 1);
+
+  if (removedIntervals.GetEnd() >= aTrackData.mHighestStartTimestamp &&
+      removedIntervals.GetStart() <= aTrackData.mHighestStartTimestamp) {
+    // The sample with the highest presentation time got removed.
+    // Rescan the trackbuffer to determine the new one.
+    TimeUnit highestStartTime;
+    for (const auto& sample : data) {
+      if (sample->mTime > highestStartTime) {
+        highestStartTime = sample->mTime;
+      }
+    }
+    MutexAutoLock mut(mMutex);
+    aTrackData.mHighestStartTimestamp = highestStartTime;
+  }
+
+  return firstRemovedIndex.ref();
+}
+
+void TrackBuffersManager::RecreateParser(bool aReuseInitData) {
+  MOZ_ASSERT(OnTaskQueue());
+  // Recreate our parser for only the data remaining. This is required
+  // as it has parsed the entire InputBuffer provided.
+  // Once the old TrackBuffer/MediaSource implementation is removed
+  // we can optimize this part. TODO
+  if (mParser) {
+    DDUNLINKCHILD(mParser.get());
+  }
+  mParser = ContainerParser::CreateForMIMEType(mType);
+  DDLINKCHILD("parser", mParser.get());
+  if (aReuseInitData && mInitData) {
+    int64_t start, end;
+    mParser->ParseStartAndEndTimestamps(MediaSpan(mInitData), start, end);
+    mProcessedInput = mInitData->Length();
+  } else {
+    mProcessedInput = 0;
+  }
+}
+
+nsTArray<TrackBuffersManager::TrackData*> TrackBuffersManager::GetTracksList() {
+  nsTArray<TrackData*> tracks;
+  if (HasVideo()) {
+    tracks.AppendElement(&mVideoTracks);
+  }
+  if (HasAudio()) {
+    tracks.AppendElement(&mAudioTracks);
+  }
+  return tracks;
+}
+
+nsTArray<const TrackBuffersManager::TrackData*>
+TrackBuffersManager::GetTracksList() const {
+  nsTArray<const TrackData*> tracks;
+  if (HasVideo()) {
+    tracks.AppendElement(&mVideoTracks);
+  }
+  if (HasAudio()) {
+    tracks.AppendElement(&mAudioTracks);
+  }
+  return tracks;
+}
+
+void TrackBuffersManager::SetAppendState(AppendState aAppendState) {
+  MSE_DEBUG("AppendState changed from %s to %s",
+            AppendStateToStr(mSourceBufferAttributes->GetAppendState()),
+            AppendStateToStr(aAppendState));
+  mSourceBufferAttributes->SetAppendState(aAppendState);
+}
+
+MediaInfo TrackBuffersManager::GetMetadata() const {
+  MutexAutoLock mut(mMutex);
+  return mInfo;
+}
+
+const TimeIntervals& TrackBuffersManager::Buffered(
+    TrackInfo::TrackType aTrack) const {
+  MOZ_ASSERT(OnTaskQueue());
+  return GetTracksData(aTrack).mBufferedRanges;
+}
+
+const media::TimeUnit& TrackBuffersManager::HighestStartTime(
+    TrackInfo::TrackType aTrack) const {
+  MOZ_ASSERT(OnTaskQueue());
+  return GetTracksData(aTrack).mHighestStartTimestamp;
+}
+
+TimeIntervals TrackBuffersManager::SafeBuffered(
+    TrackInfo::TrackType aTrack) const {
+  MutexAutoLock mut(mMutex);
+  return aTrack == TrackInfo::kVideoTrack ? mVideoBufferedRanges
+                                          : mAudioBufferedRanges;
+}
+
+TimeUnit TrackBuffersManager::HighestStartTime() const {
+  MutexAutoLock mut(mMutex);
+  TimeUnit highestStartTime;
+  for (auto& track : GetTracksList()) {
+    highestStartTime =
+        std::max(track->mHighestStartTimestamp, highestStartTime);
+  }
+  return highestStartTime;
+}
+
+TimeUnit TrackBuffersManager::HighestEndTime() const {
+  MutexAutoLock mut(mMutex);
+
+  nsTArray<const TimeIntervals*> tracks;
+  if (HasVideo()) {
+    tracks.AppendElement(&mVideoBufferedRanges);
+  }
+  if (HasAudio()) {
+    tracks.AppendElement(&mAudioBufferedRanges);
+  }
+  return HighestEndTime(tracks);
+}
+
+TimeUnit TrackBuffersManager::HighestEndTime(
+    nsTArray<const TimeIntervals*>& aTracks) const {
+  mMutex.AssertCurrentThreadOwns();
+
+  TimeUnit highestEndTime;
+
+  for (const auto& trackRanges : aTracks) {
+    highestEndTime = std::max(trackRanges->GetEnd(), highestEndTime);
+  }
+  return highestEndTime;
+}
+
+void TrackBuffersManager::ResetEvictionIndex(TrackData& aTrackData) {
+  MutexAutoLock mut(mMutex);
+  aTrackData.mEvictionIndex.Reset();
+}
+
+void TrackBuffersManager::UpdateEvictionIndex(TrackData& aTrackData,
+                                              uint32_t currentIndex) {
+  uint32_t evictable = 0;
+  TrackBuffer& data = aTrackData.GetTrackBuffer();
+  MOZ_DIAGNOSTIC_ASSERT(currentIndex >= aTrackData.mEvictionIndex.mLastIndex,
+                        "Invalid call");
+  MOZ_DIAGNOSTIC_ASSERT(
+      currentIndex == data.Length() || data[currentIndex]->mKeyframe,
+      "Must stop at keyframe");
+
+  for (uint32_t i = aTrackData.mEvictionIndex.mLastIndex; i < currentIndex;
+       i++) {
+    evictable += data[i]->ComputedSizeOfIncludingThis();
+  }
+  aTrackData.mEvictionIndex.mLastIndex = currentIndex;
+  MutexAutoLock mut(mMutex);
+  aTrackData.mEvictionIndex.mEvictable += evictable;
+}
+
+const TrackBuffersManager::TrackBuffer& TrackBuffersManager::GetTrackBuffer(
+    TrackInfo::TrackType aTrack) const {
+  MOZ_ASSERT(OnTaskQueue());
+  return GetTracksData(aTrack).GetTrackBuffer();
+}
+
+uint32_t TrackBuffersManager::FindSampleIndex(const TrackBuffer& aTrackBuffer,
+                                              const TimeInterval& aInterval) {
+  TimeUnit target = aInterval.mStart - aInterval.mFuzz;
+
+  for (uint32_t i = 0; i < aTrackBuffer.Length(); i++) {
+    const RefPtr<MediaRawData>& sample = aTrackBuffer[i];
+    if (sample->mTime >= target || sample->GetEndTime() > target) {
+      return i;
+    }
+  }
+  NS_ASSERTION(false, "FindSampleIndex called with invalid arguments");
+
+  return 0;
+}
+
+TimeUnit TrackBuffersManager::Seek(TrackInfo::TrackType aTrack,
+                                   const TimeUnit& aTime,
+                                   const TimeUnit& aFuzz) {
+  MOZ_ASSERT(OnTaskQueue());
+  AUTO_PROFILER_LABEL("TrackBuffersManager::Seek", MEDIA_PLAYBACK);
+  auto& trackBuffer = GetTracksData(aTrack);
+  const TrackBuffersManager::TrackBuffer& track = GetTrackBuffer(aTrack);
+
+  if (!track.Length()) {
+    // This a reset. It will be followed by another valid seek.
+    trackBuffer.mNextGetSampleIndex = Some(uint32_t(0));
+    trackBuffer.mNextSampleTimecode = TimeUnit();
+    trackBuffer.mNextSampleTime = TimeUnit();
+    ResetEvictionIndex(trackBuffer);
+    return TimeUnit();
+  }
+
+  uint32_t i = 0;
+
+  if (aTime != TimeUnit()) {
+    // Determine the interval of samples we're attempting to seek to.
+    TimeIntervals buffered = trackBuffer.mBufferedRanges;
+    // Fuzz factor is +/- aFuzz; as we want to only eliminate gaps
+    // that are less than aFuzz wide, we set a fuzz factor aFuzz/2.
+    buffered.SetFuzz(aFuzz / 2);
+    TimeIntervals::IndexType index = buffered.Find(aTime);
+    MOZ_ASSERT(index != TimeIntervals::NoIndex,
+               "We shouldn't be called if aTime isn't buffered");
+    TimeInterval target = buffered[index];
+    target.mFuzz = aFuzz;
+    i = FindSampleIndex(track, target);
+  }
+
+  Maybe<TimeUnit> lastKeyFrameTime;
+  TimeUnit lastKeyFrameTimecode;
+  uint32_t lastKeyFrameIndex = 0;
+  for (; i < track.Length(); i++) {
+    const RefPtr<MediaRawData>& sample = track[i];
+    TimeUnit sampleTime = sample->mTime;
+    if (sampleTime > aTime && lastKeyFrameTime.isSome()) {
+      break;
+    }
+    if (sample->mKeyframe) {
+      lastKeyFrameTimecode = sample->mTimecode;
+      lastKeyFrameTime = Some(sampleTime);
+      lastKeyFrameIndex = i;
+    }
+    if (sampleTime == aTime ||
+        (sampleTime > aTime && lastKeyFrameTime.isSome())) {
+      break;
+    }
+  }
+  MSE_DEBUG("Keyframe %s found at %" PRId64 " @ %u",
+            lastKeyFrameTime.isSome() ? "" : "not",
+            lastKeyFrameTime.refOr(TimeUnit()).ToMicroseconds(),
+            lastKeyFrameIndex);
+
+  trackBuffer.mNextGetSampleIndex = Some(lastKeyFrameIndex);
+  trackBuffer.mNextSampleTimecode = lastKeyFrameTimecode;
+  trackBuffer.mNextSampleTime = lastKeyFrameTime.refOr(TimeUnit());
+  ResetEvictionIndex(trackBuffer);
+  UpdateEvictionIndex(trackBuffer, lastKeyFrameIndex);
+
+  return lastKeyFrameTime.refOr(TimeUnit());
+}
+
+uint32_t TrackBuffersManager::SkipToNextRandomAccessPoint(
+    TrackInfo::TrackType aTrack, const TimeUnit& aTimeThreadshold,
+    const media::TimeUnit& aFuzz, bool& aFound) {
+  mTaskQueueCapability->AssertOnCurrentThread();
+  AUTO_PROFILER_LABEL("TrackBuffersManager::SkipToNextRandomAccessPoint",
+                      MEDIA_PLAYBACK);
+  uint32_t parsed = 0;
+  auto& trackData = GetTracksData(aTrack);
+  const TrackBuffer& track = GetTrackBuffer(aTrack);
+  aFound = false;
+
+  // SkipToNextRandomAccessPoint can only be called if aTimeThreadshold is known
+  // to be buffered.
+
+  if (NS_FAILED(SetNextGetSampleIndexIfNeeded(aTrack, aFuzz))) {
+    return 0;
+  }
+
+  TimeUnit nextSampleTimecode = trackData.mNextSampleTimecode;
+  TimeUnit nextSampleTime = trackData.mNextSampleTime;
+  uint32_t i = trackData.mNextGetSampleIndex.ref();
+  int32_t originalPos = i;
+
+  for (; i < track.Length(); i++) {
+    const MediaRawData* sample =
+        GetSample(aTrack, i, nextSampleTimecode, nextSampleTime, aFuzz);
+    if (!sample) {
+      break;
+    }
+    if (sample->mKeyframe && sample->mTime >= aTimeThreadshold) {
+      aFound = true;
+      break;
+    }
+    nextSampleTimecode = sample->GetEndTimecode();
+    nextSampleTime = sample->GetEndTime();
+    parsed++;
+  }
+
+  // Adjust the next demux time and index so that the next call to
+  // SkipToNextRandomAccessPoint will not count again the parsed sample as
+  // skipped.
+  if (aFound) {
+    trackData.mNextSampleTimecode = track[i]->mTimecode;
+    trackData.mNextSampleTime = track[i]->mTime;
+    trackData.mNextGetSampleIndex = Some(i);
+  } else if (i > 0) {
+    // Go back to the previous keyframe or the original position so the next
+    // demux can succeed and be decoded.
+    for (int j = i - 1; j >= originalPos; j--) {
+      const RefPtr<MediaRawData>& sample = track[j];
+      if (sample->mKeyframe) {
+        trackData.mNextSampleTimecode = sample->mTimecode;
+        trackData.mNextSampleTime = sample->mTime;
+        trackData.mNextGetSampleIndex = Some(uint32_t(j));
+        // We are unable to skip to a keyframe past aTimeThreshold, however
+        // we are speeding up decoding by dropping the unplayable frames.
+        // So we can mark aFound as true.
+        aFound = true;
+        break;
+      }
+      parsed--;
+    }
+  }
+
+  if (aFound) {
+    UpdateEvictionIndex(trackData, trackData.mNextGetSampleIndex.ref());
+  }
+
+  return parsed;
+}
+
+const MediaRawData* TrackBuffersManager::GetSample(TrackInfo::TrackType aTrack,
+                                                   uint32_t aIndex,
+                                                   const TimeUnit& aExpectedDts,
+                                                   const TimeUnit& aExpectedPts,
+                                                   const TimeUnit& aFuzz) {
+  MOZ_ASSERT(OnTaskQueue());
+  const TrackBuffer& track = GetTrackBuffer(aTrack);
+
+  if (aIndex >= track.Length()) {
+    // reached the end.
+    return nullptr;
+  }
+
+  if (!(aExpectedDts + aFuzz).IsValid() || !(aExpectedPts + aFuzz).IsValid()) {
+    // Time overflow, it seems like we also reached the end.
+    return nullptr;
+  }
+
+  const RefPtr<MediaRawData>& sample = track[aIndex];
+  if (!aIndex || sample->mTimecode <= aExpectedDts + aFuzz ||
+      sample->mTime <= aExpectedPts + aFuzz) {
+    MOZ_DIAGNOSTIC_ASSERT(sample->HasValidTime());
+    return sample;
+  }
+
+  // Gap is too big. End of Stream or Waiting for Data.
+  // TODO, check that we have continuous data based on the sanitized buffered
+  // range instead.
+  return nullptr;
+}
+
+already_AddRefed<MediaRawData> TrackBuffersManager::GetSample(
+    TrackInfo::TrackType aTrack, const TimeUnit& aFuzz, MediaResult& aResult) {
+  mTaskQueueCapability->AssertOnCurrentThread();
+  AUTO_PROFILER_LABEL("TrackBuffersManager::GetSample", MEDIA_PLAYBACK);
+  auto& trackData = GetTracksData(aTrack);
+  const TrackBuffer& track = GetTrackBuffer(aTrack);
+
+  aResult = NS_ERROR_DOM_MEDIA_WAITING_FOR_DATA;
+
+  if (trackData.mNextGetSampleIndex.isSome()) {
+    if (trackData.mNextGetSampleIndex.ref() >= track.Length()) {
+      aResult = NS_ERROR_DOM_MEDIA_END_OF_STREAM;
+      return nullptr;
+    }
+    const MediaRawData* sample = GetSample(
+        aTrack, trackData.mNextGetSampleIndex.ref(),
+        trackData.mNextSampleTimecode, trackData.mNextSampleTime, aFuzz);
+    if (!sample) {
+      return nullptr;
+    }
+
+    RefPtr<MediaRawData> p = sample->Clone();
+    if (!p) {
+      aResult = MediaResult(NS_ERROR_OUT_OF_MEMORY, __func__);
+      return nullptr;
+    }
+    if (p->mKeyframe) {
+      UpdateEvictionIndex(trackData, trackData.mNextGetSampleIndex.ref());
+    }
+    trackData.mNextGetSampleIndex.ref()++;
+    // Estimate decode timestamp and timestamp of the next sample.
+    TimeUnit nextSampleTimecode = sample->GetEndTimecode();
+    TimeUnit nextSampleTime = sample->GetEndTime();
+    const MediaRawData* nextSample =
+        GetSample(aTrack, trackData.mNextGetSampleIndex.ref(),
+                  nextSampleTimecode, nextSampleTime, aFuzz);
+    if (nextSample) {
+      // We have a valid next sample, can use exact values.
+      trackData.mNextSampleTimecode = nextSample->mTimecode;
+      trackData.mNextSampleTime = nextSample->mTime;
+    } else {
+      // Next sample isn't available yet. Use estimates.
+      trackData.mNextSampleTimecode = nextSampleTimecode;
+      trackData.mNextSampleTime = nextSampleTime;
+    }
+    aResult = NS_OK;
+    return p.forget();
+  }
+
+  aResult = SetNextGetSampleIndexIfNeeded(aTrack, aFuzz);
+
+  if (NS_FAILED(aResult)) {
+    return nullptr;
+  }
+
+  MOZ_RELEASE_ASSERT(trackData.mNextGetSampleIndex.isSome() &&
+                     trackData.mNextGetSampleIndex.ref() < track.Length());
+  const RefPtr<MediaRawData>& sample =
+      track[trackData.mNextGetSampleIndex.ref()];
+  RefPtr<MediaRawData> p = sample->Clone();
+  if (!p) {
+    // OOM
+    aResult = MediaResult(NS_ERROR_OUT_OF_MEMORY, __func__);
+    return nullptr;
+  }
+  MOZ_DIAGNOSTIC_ASSERT(p->HasValidTime());
+
+  // Find the previous keyframe to calculate the evictable amount.
+  uint32_t i = trackData.mNextGetSampleIndex.ref();
+  for (; !track[i]->mKeyframe; i--) {
+  }
+  UpdateEvictionIndex(trackData, i);
+
+  trackData.mNextGetSampleIndex.ref()++;
+  trackData.mNextSampleTimecode = sample->GetEndTimecode();
+  trackData.mNextSampleTime = sample->GetEndTime();
+  return p.forget();
+}
+
+int32_t TrackBuffersManager::FindCurrentPosition(TrackInfo::TrackType aTrack,
+                                                 const TimeUnit& aFuzz) const {
+  MOZ_ASSERT(OnTaskQueue());
+  auto& trackData = GetTracksData(aTrack);
+  const TrackBuffer& track = GetTrackBuffer(aTrack);
+
+  // Perform an exact search first.
+  for (uint32_t i = 0; i < track.Length(); i++) {
+    const RefPtr<MediaRawData>& sample = track[i];
+    TimeInterval sampleInterval{sample->mTimecode, sample->GetEndTimecode()};
+
+    if (sampleInterval.ContainsStrict(trackData.mNextSampleTimecode)) {
+      return i;
+    }
+    if (sampleInterval.mStart > trackData.mNextSampleTimecode) {
+      // Samples are ordered by timecode. There's no need to search
+      // any further.
+      break;
+    }
+  }
+
+  for (uint32_t i = 0; i < track.Length(); i++) {
+    const RefPtr<MediaRawData>& sample = track[i];
+    TimeInterval sampleInterval{sample->mTimecode, sample->GetEndTimecode(),
+                                aFuzz};
+
+    if (sampleInterval.ContainsWithStrictEnd(trackData.mNextSampleTimecode)) {
+      return i;
+    }
+    if (sampleInterval.mStart - aFuzz > trackData.mNextSampleTimecode) {
+      // Samples are ordered by timecode. There's no need to search
+      // any further.
+      break;
+    }
+  }
+
+  // We couldn't find our sample by decode timestamp. Attempt to find it using
+  // presentation timestamp. There will likely be small jerkiness.
+  for (uint32_t i = 0; i < track.Length(); i++) {
+    const RefPtr<MediaRawData>& sample = track[i];
+    TimeInterval sampleInterval{sample->mTime, sample->GetEndTime(), aFuzz};
+
+    if (sampleInterval.ContainsWithStrictEnd(trackData.mNextSampleTimecode)) {
+      return i;
+    }
+  }
+
+  // Still not found.
+  return -1;
+}
+
+uint32_t TrackBuffersManager::Evictable(TrackInfo::TrackType aTrack) const {
+  MutexAutoLock mut(mMutex);
+  return GetTracksData(aTrack).mEvictionIndex.mEvictable;
+}
+
+TimeUnit TrackBuffersManager::GetNextRandomAccessPoint(
+    TrackInfo::TrackType aTrack, const TimeUnit& aFuzz) {
+  mTaskQueueCapability->AssertOnCurrentThread();
+
+  // So first determine the current position in the track buffer if necessary.
+  if (NS_FAILED(SetNextGetSampleIndexIfNeeded(aTrack, aFuzz))) {
+    return TimeUnit::FromInfinity();
+  }
+
+  auto& trackData = GetTracksData(aTrack);
+  const TrackBuffersManager::TrackBuffer& track = GetTrackBuffer(aTrack);
+
+  uint32_t i = trackData.mNextGetSampleIndex.ref();
+  TimeUnit nextSampleTimecode = trackData.mNextSampleTimecode;
+  TimeUnit nextSampleTime = trackData.mNextSampleTime;
+
+  for (; i < track.Length(); i++) {
+    const MediaRawData* sample =
+        GetSample(aTrack, i, nextSampleTimecode, nextSampleTime, aFuzz);
+    if (!sample) {
+      break;
+    }
+    if (sample->mKeyframe) {
+      return sample->mTime;
+    }
+    nextSampleTimecode = sample->GetEndTimecode();
+    nextSampleTime = sample->GetEndTime();
+  }
+  return TimeUnit::FromInfinity();
+}
+
+nsresult TrackBuffersManager::SetNextGetSampleIndexIfNeeded(
+    TrackInfo::TrackType aTrack, const TimeUnit& aFuzz) {
+  MOZ_ASSERT(OnTaskQueue());
+  auto& trackData = GetTracksData(aTrack);
+  const TrackBuffer& track = GetTrackBuffer(aTrack);
+
+  if (trackData.mNextGetSampleIndex.isSome()) {
+    // We already know the next GetSample index.
+    return NS_OK;
+  }
+
+  if (!track.Length()) {
+    // There's nothing to find yet.
+    return NS_ERROR_DOM_MEDIA_END_OF_STREAM;
+  }
+
+  if (trackData.mNextSampleTimecode == TimeUnit()) {
+    // First demux, get first sample.
+    trackData.mNextGetSampleIndex = Some(0u);
+    return NS_OK;
+  }
+
+  if (trackData.mNextSampleTimecode > track.LastElement()->GetEndTimecode()) {
+    // The next element is past our last sample. We're done.
+    trackData.mNextGetSampleIndex = Some(uint32_t(track.Length()));
+    return NS_ERROR_DOM_MEDIA_END_OF_STREAM;
+  }
+
+  int32_t pos = FindCurrentPosition(aTrack, aFuzz);
+  if (pos < 0) {
+    // Not found, must wait for more data.
+    MSE_DEBUG("Couldn't find sample (pts:%" PRId64 " dts:%" PRId64 ")",
+              trackData.mNextSampleTime.ToMicroseconds(),
+              trackData.mNextSampleTimecode.ToMicroseconds());
+    return NS_ERROR_DOM_MEDIA_WAITING_FOR_DATA;
+  }
+  trackData.mNextGetSampleIndex = Some(uint32_t(pos));
+  return NS_OK;
+}
+
+void TrackBuffersManager::TrackData::AddSizeOfResources(
+    MediaSourceDecoder::ResourceSizes* aSizes) const {
+  for (const TrackBuffer& buffer : mBuffers) {
+    for (const MediaRawData* data : buffer) {
+      aSizes->mByteSize += data->SizeOfIncludingThis(aSizes->mMallocSizeOf);
+    }
+  }
+}
+
+RefPtr<GenericPromise> TrackBuffersManager::RequestDebugInfo(
+    dom::TrackBuffersManagerDebugInfo& aInfo) const {
+  const RefPtr<TaskQueue> taskQueue = GetTaskQueueSafe();
+  if (!taskQueue) {
+    return GenericPromise::CreateAndResolve(true, __func__);
+  }
+  if (!taskQueue->IsCurrentThreadIn()) {
+    // Run the request on the task queue if it's not already.
+    return InvokeAsync(taskQueue.get(), __func__,
+                       [this, self = RefPtr{this}, &aInfo] {
+                         return RequestDebugInfo(aInfo);
+                       });
+  }
+  mTaskQueueCapability->AssertOnCurrentThread();
+  GetDebugInfo(aInfo);
+  return GenericPromise::CreateAndResolve(true, __func__);
+}
+
+void TrackBuffersManager::GetDebugInfo(
+    dom::TrackBuffersManagerDebugInfo& aInfo) const {
+  MOZ_ASSERT(OnTaskQueue(),
+             "This shouldn't be called off the task queue because we're about "
+             "to touch a lot of data that is used on the task queue");
+  CopyUTF8toUTF16(mType.Type().AsString(), aInfo.mType);
+
+  if (HasAudio()) {
+    aInfo.mNextSampleTime = mAudioTracks.mNextSampleTime.ToSeconds();
+    aInfo.mNumSamples = mAudioTracks.mBuffers[0].Length();
+    aInfo.mBufferSize = mAudioTracks.mSizeBuffer;
+    aInfo.mEvictable = Evictable(TrackInfo::kAudioTrack);
+    aInfo.mNextGetSampleIndex = mAudioTracks.mNextGetSampleIndex.valueOr(-1);
+    aInfo.mNextInsertionIndex = mAudioTracks.mNextInsertionIndex.valueOr(-1);
+    media::TimeIntervals ranges = SafeBuffered(TrackInfo::kAudioTrack);
+    dom::Sequence<dom::BufferRange> items;
+    for (uint32_t i = 0; i < ranges.Length(); ++i) {
+      // dom::Sequence is a FallibleTArray
+      dom::BufferRange* range = items.AppendElement(fallible);
+      if (!range) {
+        break;
+      }
+      range->mStart = ranges.Start(i).ToSeconds();
+      range->mEnd = ranges.End(i).ToSeconds();
+    }
+    aInfo.mRanges = std::move(items);
+  } else if (HasVideo()) {
+    aInfo.mNextSampleTime = mVideoTracks.mNextSampleTime.ToSeconds();
+    aInfo.mNumSamples = mVideoTracks.mBuffers[0].Length();
+    aInfo.mBufferSize = mVideoTracks.mSizeBuffer;
+    aInfo.mEvictable = Evictable(TrackInfo::kVideoTrack);
+    aInfo.mNextGetSampleIndex = mVideoTracks.mNextGetSampleIndex.valueOr(-1);
+    aInfo.mNextInsertionIndex = mVideoTracks.mNextInsertionIndex.valueOr(-1);
+    media::TimeIntervals ranges = SafeBuffered(TrackInfo::kVideoTrack);
+    dom::Sequence<dom::BufferRange> items;
+    for (uint32_t i = 0; i < ranges.Length(); ++i) {
+      // dom::Sequence is a FallibleTArray
+      dom::BufferRange* range = items.AppendElement(fallible);
+      if (!range) {
+        break;
+      }
+      range->mStart = ranges.Start(i).ToSeconds();
+      range->mEnd = ranges.End(i).ToSeconds();
+    }
+    aInfo.mRanges = std::move(items);
+  }
+}
+
+void TrackBuffersManager::AddSizeOfResources(
+    MediaSourceDecoder::ResourceSizes* aSizes) const {
+  mTaskQueueCapability->AssertOnCurrentThread();
+
+  if (mInputBuffer.isSome() && mInputBuffer->Buffer()) {
+    // mInputBuffer should be the sole owner of the underlying buffer, so this
+    // won't double count.
+    aSizes->mByteSize += mInputBuffer->Buffer()->ShallowSizeOfIncludingThis(
+        aSizes->mMallocSizeOf);
+  }
+  if (mInitData) {
+    aSizes->mByteSize +=
+        mInitData->ShallowSizeOfIncludingThis(aSizes->mMallocSizeOf);
+  }
+  if (mPendingInputBuffer.isSome() && mPendingInputBuffer->Buffer()) {
+    // mPendingInputBuffer should be the sole owner of the underlying buffer, so
+    // this won't double count.
+    aSizes->mByteSize +=
+        mPendingInputBuffer->Buffer()->ShallowSizeOfIncludingThis(
+            aSizes->mMallocSizeOf);
+  }
+
+  mVideoTracks.AddSizeOfResources(aSizes);
+  mAudioTracks.AddSizeOfResources(aSizes);
+}
+
+}  // namespace mozilla
+#undef MSE_DEBUG
+#undef MSE_DEBUGV
+#undef SAMPLE_DEBUG
diff --git a/dom/media/mediasource/TrackBuffersManager.h b/dom/media/mediasource/TrackBuffersManager.h
new file mode 100644
index 0000000000..0b3b64b8fe
--- /dev/null
+++ b/dom/media/mediasource/TrackBuffersManager.h
@@ -0,0 +1,568 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_TRACKBUFFERSMANAGER_H_
+#define MOZILLA_TRACKBUFFERSMANAGER_H_
+
+#include "mozilla/Atomics.h"
+#include "mozilla/EventTargetCapability.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/NotNull.h"
+#include "mozilla/TaskQueue.h"
+#include "mozilla/dom/MediaDebugInfoBinding.h"
+
+#include "MediaContainerType.h"
+#include "MediaData.h"
+#include "MediaDataDemuxer.h"
+#include "MediaResult.h"
+#include "MediaSourceDecoder.h"
+#include "MediaSpan.h"
+#include "SourceBufferTask.h"
+#include "TimeUnits.h"
+#include "nsTArray.h"
+
+namespace mozilla {
+
+class AbstractThread;
+class ContainerParser;
+class MediaByteBuffer;
+class MediaRawData;
+class MediaSourceDemuxer;
+class SourceBufferResource;
+
+class SourceBufferTaskQueue {
+ public:
+  SourceBufferTaskQueue() = default;
+
+  ~SourceBufferTaskQueue() {
+    MOZ_ASSERT(mQueue.IsEmpty(), "All tasks must have been processed");
+  }
+
+  void Push(SourceBufferTask* aTask) { mQueue.AppendElement(aTask); }
+
+  already_AddRefed<SourceBufferTask> Pop() {
+    if (!mQueue.Length()) {
+      return nullptr;
+    }
+    RefPtr<SourceBufferTask> task = std::move(mQueue[0]);
+    mQueue.RemoveElementAt(0);
+    return task.forget();
+  }
+
+  nsTArray<RefPtr<SourceBufferTask>>::size_type Length() const {
+    return mQueue.Length();
+  }
+
+ private:
+  nsTArray<RefPtr<SourceBufferTask>> mQueue;
+};
+
+DDLoggedTypeDeclName(TrackBuffersManager);
+
+class TrackBuffersManager final
+    : public DecoderDoctorLifeLogger<TrackBuffersManager> {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(TrackBuffersManager);
+
+  enum class EvictDataResult : int8_t {
+    NO_DATA_EVICTED,
+    CANT_EVICT,
+    BUFFER_FULL,
+  };
+
+  typedef TrackInfo::TrackType TrackType;
+  typedef MediaData::Type MediaType;
+  typedef nsTArray<RefPtr<MediaRawData>> TrackBuffer;
+  typedef SourceBufferTask::AppendPromise AppendPromise;
+  typedef SourceBufferTask::RangeRemovalPromise RangeRemovalPromise;
+
+  // Interface for SourceBuffer
+  TrackBuffersManager(MediaSourceDecoder* aParentDecoder,
+                      const MediaContainerType& aType);
+
+  // Queue a task to add data to the end of the input buffer and run the MSE
+  // Buffer Append Algorithm
+  // 3.5.5 Buffer Append Algorithm.
+  // http://w3c.github.io/media-source/index.html#sourcebuffer-buffer-append
+  RefPtr<AppendPromise> AppendData(already_AddRefed<MediaByteBuffer> aData,
+                                   const SourceBufferAttributes& aAttributes);
+
+  // Queue a task to abort any pending AppendData.
+  // Does nothing at this stage.
+  void AbortAppendData();
+
+  // Queue a task to run MSE Reset Parser State Algorithm.
+  // 3.5.2 Reset Parser State
+  void ResetParserState(SourceBufferAttributes& aAttributes);
+
+  // Queue a task to run the MSE range removal algorithm.
+  // http://w3c.github.io/media-source/#sourcebuffer-coded-frame-removal
+  RefPtr<RangeRemovalPromise> RangeRemoval(media::TimeUnit aStart,
+                                           media::TimeUnit aEnd);
+
+  // Schedule data eviction if necessary as the next call to AppendData will
+  // add aSize bytes.
+  // Eviction is done in two steps, first remove data up to aPlaybackTime
+  // and if still more space is needed remove from the end.
+  EvictDataResult EvictData(const media::TimeUnit& aPlaybackTime,
+                            int64_t aSize);
+
+  // Queue a task to run ChangeType
+  void ChangeType(const MediaContainerType& aType);
+
+  // Returns the buffered range currently managed.
+  // This may be called on any thread.
+  // Buffered must conform to
+  // http://w3c.github.io/media-source/index.html#widl-SourceBuffer-buffered
+  media::TimeIntervals Buffered() const;
+  media::TimeUnit HighestStartTime() const;
+  media::TimeUnit HighestEndTime() const;
+
+  // Return the size of the data managed by this SourceBufferContentManager.
+  int64_t GetSize() const;
+
+  // Indicate that the MediaSource parent object got into "ended" state.
+  void Ended();
+
+  // The parent SourceBuffer is about to be destroyed.
+  void Detach();
+
+  int64_t EvictionThreshold() const;
+
+  // Interface for MediaSourceDemuxer
+  MediaInfo GetMetadata() const;
+  const TrackBuffer& GetTrackBuffer(TrackInfo::TrackType aTrack) const;
+  const media::TimeIntervals& Buffered(TrackInfo::TrackType) const;
+  const media::TimeUnit& HighestStartTime(TrackInfo::TrackType) const;
+  media::TimeIntervals SafeBuffered(TrackInfo::TrackType) const;
+  bool IsEnded() const { return mEnded; }
+  uint32_t Evictable(TrackInfo::TrackType aTrack) const;
+  media::TimeUnit Seek(TrackInfo::TrackType aTrack,
+                       const media::TimeUnit& aTime,
+                       const media::TimeUnit& aFuzz);
+  uint32_t SkipToNextRandomAccessPoint(TrackInfo::TrackType aTrack,
+                                       const media::TimeUnit& aTimeThreadshold,
+                                       const media::TimeUnit& aFuzz,
+                                       bool& aFound);
+
+  already_AddRefed<MediaRawData> GetSample(TrackInfo::TrackType aTrack,
+                                           const media::TimeUnit& aFuzz,
+                                           MediaResult& aResult);
+  int32_t FindCurrentPosition(TrackInfo::TrackType aTrack,
+                              const media::TimeUnit& aFuzz) const
+      MOZ_REQUIRES(mTaskQueueCapability);
+
+  // Will set the next GetSample index if needed. This information is determined
+  // through the value of mNextSampleTimecode. Return false if the index
+  // couldn't be determined or if there's nothing more that could be demuxed.
+  // This occurs if either the track buffer doesn't contain the required
+  // timecode or is empty.
+  nsresult SetNextGetSampleIndexIfNeeded(TrackInfo::TrackType aTrack,
+                                         const media::TimeUnit& aFuzz)
+      MOZ_REQUIRES(mTaskQueueCapability);
+
+  media::TimeUnit GetNextRandomAccessPoint(TrackInfo::TrackType aTrack,
+                                           const media::TimeUnit& aFuzz);
+
+  // Requests that the TrackBuffersManager populates aInfo with debug
+  // information. This may be done asynchronously, and aInfo should *not* be
+  // accessed by the caller until the returned promise is resolved or rejected.
+  RefPtr<GenericPromise> RequestDebugInfo(
+      dom::TrackBuffersManagerDebugInfo& aInfo) const;
+  void AddSizeOfResources(MediaSourceDecoder::ResourceSizes* aSizes) const;
+
+ private:
+  typedef MozPromise<bool, MediaResult, /* IsExclusive = */ true>
+      CodedFrameProcessingPromise;
+
+  ~TrackBuffersManager();
+  // All following functions run on the taskqueue.
+  RefPtr<AppendPromise> DoAppendData(already_AddRefed<MediaByteBuffer> aData,
+                                     const SourceBufferAttributes& aAttributes);
+  void ScheduleSegmentParserLoop() MOZ_REQUIRES(mTaskQueueCapability);
+  void SegmentParserLoop() MOZ_REQUIRES(mTaskQueueCapability);
+  void InitializationSegmentReceived() MOZ_REQUIRES(mTaskQueueCapability);
+  void ShutdownDemuxers() MOZ_REQUIRES(mTaskQueueCapability);
+  void CreateDemuxerforMIMEType() MOZ_REQUIRES(mTaskQueueCapability);
+  void ResetDemuxingState() MOZ_REQUIRES(mTaskQueueCapability);
+  void NeedMoreData() MOZ_REQUIRES(mTaskQueueCapability);
+  void RejectAppend(const MediaResult& aRejectValue, const char* aName)
+      MOZ_REQUIRES(mTaskQueueCapability);
+  // Will return a promise that will be resolved once all frames of the current
+  // media segment have been processed.
+  RefPtr<CodedFrameProcessingPromise> CodedFrameProcessing()
+      MOZ_REQUIRES(mTaskQueueCapability);
+  void CompleteCodedFrameProcessing() MOZ_REQUIRES(mTaskQueueCapability);
+  // Called by ResetParserState.
+  void CompleteResetParserState() MOZ_REQUIRES(mTaskQueueCapability);
+  RefPtr<RangeRemovalPromise> CodedFrameRemovalWithPromise(
+      media::TimeInterval aInterval) MOZ_REQUIRES(mTaskQueueCapability);
+  bool CodedFrameRemoval(media::TimeInterval aInterval)
+      MOZ_REQUIRES(mTaskQueueCapability);
+  // Removes all coded frames -- this is not to spec and should be used as a
+  // last resort to clear buffers only if other methods cannot.
+  void RemoveAllCodedFrames() MOZ_REQUIRES(mTaskQueueCapability);
+  void SetAppendState(SourceBufferAttributes::AppendState aAppendState)
+      MOZ_REQUIRES(mTaskQueueCapability);
+
+  bool HasVideo() const { return mVideoTracks.mNumTracks > 0; }
+  bool HasAudio() const { return mAudioTracks.mNumTracks > 0; }
+
+  // The input buffer as per
+  // http://w3c.github.io/media-source/index.html#sourcebuffer-input-buffer
+  Maybe<MediaSpan> mInputBuffer MOZ_GUARDED_BY(mTaskQueueCapability);
+  // Buffer full flag as per
+  // https://w3c.github.io/media-source/#sourcebuffer-buffer-full-flag. Accessed
+  // on both the main thread and the task queue.
+  Atomic<bool> mBufferFull;
+  bool mFirstInitializationSegmentReceived MOZ_GUARDED_BY(mTaskQueueCapability);
+  bool mChangeTypeReceived MOZ_GUARDED_BY(mTaskQueueCapability);
+  // Set to true once a new segment is started.
+  bool mNewMediaSegmentStarted MOZ_GUARDED_BY(mTaskQueueCapability);
+  bool mActiveTrack MOZ_GUARDED_BY(mTaskQueueCapability);
+  MediaContainerType mType MOZ_GUARDED_BY(mTaskQueueCapability);
+
+  // ContainerParser objects and methods.
+  // Those are used to parse the incoming input buffer.
+
+  // Recreate the ContainerParser and if aReuseInitData is true then
+  // feed it with the previous init segment found.
+  void RecreateParser(bool aReuseInitData) MOZ_REQUIRES(mTaskQueueCapability);
+  UniquePtr<ContainerParser> mParser;
+
+  // Demuxer objects and methods.
+  void AppendDataToCurrentInputBuffer(const MediaSpan& aData)
+      MOZ_REQUIRES(mTaskQueueCapability);
+
+  RefPtr<MediaByteBuffer> mInitData MOZ_GUARDED_BY(mTaskQueueCapability);
+
+  // Checks if a new set of init data is a repeat of the last set of init data
+  // received. Because streams may retransmit the same init data (or
+  // functionally equivalent init data) we do not want to perform costly
+  // operations each time we receive init data, only when it's actually
+  // different data.
+  bool IsRepeatInitData(const MediaInfo& aNewMediaInfo) const
+      MOZ_REQUIRES(mTaskQueueCapability);
+
+  // Temporary input buffer to handle partial media segment header.
+  // We store the current input buffer content into it should we need to
+  // reinitialize the demuxer once we have some samples and a discontinuity is
+  // detected.
+  Maybe<MediaSpan> mPendingInputBuffer MOZ_GUARDED_BY(mTaskQueueCapability);
+  RefPtr<SourceBufferResource> mCurrentInputBuffer
+      MOZ_GUARDED_BY(mTaskQueueCapability);
+  RefPtr<MediaDataDemuxer> mInputDemuxer MOZ_GUARDED_BY(mTaskQueueCapability);
+  // Length already processed in current media segment.
+  uint64_t mProcessedInput MOZ_GUARDED_BY(mTaskQueueCapability);
+  Maybe<media::TimeUnit> mLastParsedEndTime
+      MOZ_GUARDED_BY(mTaskQueueCapability);
+
+  void OnDemuxerInitDone(const MediaResult& aResult);
+  void OnDemuxerInitFailed(const MediaResult& aFailure);
+  void OnDemuxerResetDone(const MediaResult& aResult)
+      MOZ_REQUIRES(mTaskQueueCapability);
+  MozPromiseRequestHolder<MediaDataDemuxer::InitPromise> mDemuxerInitRequest;
+
+  void OnDemuxFailed(TrackType aTrack, const MediaResult& aError)
+      MOZ_REQUIRES(mTaskQueueCapability);
+  void DoDemuxVideo() MOZ_REQUIRES(mTaskQueueCapability);
+  void OnVideoDemuxCompleted(RefPtr<MediaTrackDemuxer::SamplesHolder> aSamples);
+  void OnVideoDemuxFailed(const MediaResult& aError) {
+    mVideoTracks.mDemuxRequest.Complete();
+    mTaskQueueCapability->AssertOnCurrentThread();
+    OnDemuxFailed(TrackType::kVideoTrack, aError);
+  }
+  void DoDemuxAudio() MOZ_REQUIRES(mTaskQueueCapability);
+  void OnAudioDemuxCompleted(RefPtr<MediaTrackDemuxer::SamplesHolder> aSamples);
+  void OnAudioDemuxFailed(const MediaResult& aError) {
+    mAudioTracks.mDemuxRequest.Complete();
+    mTaskQueueCapability->AssertOnCurrentThread();
+    OnDemuxFailed(TrackType::kAudioTrack, aError);
+  }
+
+  // Dispatches an "encrypted" event is any sample in array has initData
+  // present.
+  void MaybeDispatchEncryptedEvent(
+      const nsTArray<RefPtr<MediaRawData>>& aSamples);
+
+  void DoEvictData(const media::TimeUnit& aPlaybackTime, int64_t aSizeToEvict)
+      MOZ_REQUIRES(mTaskQueueCapability);
+
+  void GetDebugInfo(dom::TrackBuffersManagerDebugInfo& aInfo) const
+      MOZ_REQUIRES(mTaskQueueCapability);
+
+  struct TrackData {
+    TrackData() : mNumTracks(0), mNeedRandomAccessPoint(true), mSizeBuffer(0) {}
+    Atomic<uint32_t> mNumTracks;
+    // Definition of variables:
+    // https://w3c.github.io/media-source/#track-buffers
+    // Last decode timestamp variable that stores the decode timestamp of the
+    // last coded frame appended in the current coded frame group.
+    // The variable is initially unset to indicate that no coded frames have
+    // been appended yet.
+    Maybe<media::TimeUnit> mLastDecodeTimestamp;
+    // Last frame duration variable that stores the coded frame duration of the
+    // last coded frame appended in the current coded frame group.
+    // The variable is initially unset to indicate that no coded frames have
+    // been appended yet.
+    Maybe<media::TimeUnit> mLastFrameDuration;
+    // Highest end timestamp variable that stores the highest coded frame end
+    // timestamp across all coded frames in the current coded frame group that
+    // were appended to this track buffer.
+    // The variable is initially unset to indicate that no coded frames have
+    // been appended yet.
+    Maybe<media::TimeUnit> mHighestEndTimestamp;
+    // Highest presentation timestamp in track buffer.
+    // Protected by global monitor, except when reading on the task queue as it
+    // is only written there.
+    media::TimeUnit mHighestStartTimestamp;
+    // Longest frame duration seen since last random access point.
+    // Only ever accessed when mLastDecodeTimestamp and mLastFrameDuration are
+    // set.
+    media::TimeUnit mLongestFrameDuration;
+    // Need random access point flag variable that keeps track of whether the
+    // track buffer is waiting for a random access point coded frame.
+    // The variable is initially set to true to indicate that random access
+    // point coded frame is needed before anything can be added to the track
+    // buffer.
+    bool mNeedRandomAccessPoint;
+    RefPtr<MediaTrackDemuxer> mDemuxer;
+    MozPromiseRequestHolder<MediaTrackDemuxer::SamplesPromise> mDemuxRequest;
+    // Highest end timestamp of the last media segment demuxed.
+    media::TimeUnit mLastParsedEndTime;
+
+    // If set, position where the next contiguous frame will be inserted.
+    // If a discontinuity is detected, it will be unset and recalculated upon
+    // the next insertion.
+    Maybe<uint32_t> mNextInsertionIndex;
+    // Samples just demuxed, but not yet parsed.
+    TrackBuffer mQueuedSamples;
+    const TrackBuffer& GetTrackBuffer() const {
+      MOZ_RELEASE_ASSERT(mBuffers.Length(),
+                         "TrackBuffer must have been created");
+      return mBuffers.LastElement();
+    }
+    TrackBuffer& GetTrackBuffer() {
+      MOZ_RELEASE_ASSERT(mBuffers.Length(),
+                         "TrackBuffer must have been created");
+      return mBuffers.LastElement();
+    }
+    // We only manage a single track of each type at this time.
+    nsTArray<TrackBuffer> mBuffers;
+    // Track buffer ranges variable that represents the presentation time ranges
+    // occupied by the coded frames currently stored in the track buffer.
+    media::TimeIntervals mBufferedRanges;
+    // Sanitized mBufferedRanges with a fuzz of half a sample's duration applied
+    // This buffered ranges is the basis of what is exposed to the JS.
+    media::TimeIntervals mSanitizedBufferedRanges;
+    // Byte size of all samples contained in this track buffer.
+    uint32_t mSizeBuffer;
+    // TrackInfo of the first metadata received.
+    RefPtr<TrackInfoSharedPtr> mInfo;
+    // TrackInfo of the last metadata parsed (updated with each init segment.
+    RefPtr<TrackInfoSharedPtr> mLastInfo;
+
+    // If set, position of the next sample to be retrieved by GetSample().
+    // If the position is equal to the TrackBuffer's length, it indicates that
+    // we've reached EOS.
+    Maybe<uint32_t> mNextGetSampleIndex;
+    // Approximation of the next sample's decode timestamp.
+    media::TimeUnit mNextSampleTimecode;
+    // Approximation of the next sample's presentation timestamp.
+    media::TimeUnit mNextSampleTime;
+
+    struct EvictionIndex {
+      EvictionIndex() { Reset(); }
+      void Reset() {
+        mEvictable = 0;
+        mLastIndex = 0;
+      }
+      uint32_t mEvictable;
+      uint32_t mLastIndex;
+    };
+    // Size of data that can be safely evicted during the next eviction
+    // cycle.
+    // We consider as evictable all frames up to the last keyframe prior to
+    // mNextGetSampleIndex. If mNextGetSampleIndex isn't set, then we assume
+    // that we can't yet evict data.
+    // Protected by global monitor, except when reading on the task queue as it
+    // is only written there.
+    EvictionIndex mEvictionIndex;
+
+    void ResetAppendState() {
+      mLastDecodeTimestamp.reset();
+      mLastFrameDuration.reset();
+      mHighestEndTimestamp.reset();
+      mNeedRandomAccessPoint = true;
+      mNextInsertionIndex.reset();
+    }
+
+    void Reset() {
+      ResetAppendState();
+      mEvictionIndex.Reset();
+      for (auto& buffer : mBuffers) {
+        buffer.Clear();
+      }
+      mSizeBuffer = 0;
+      mNextGetSampleIndex.reset();
+      mBufferedRanges.Clear();
+      mSanitizedBufferedRanges.Clear();
+    }
+
+    void AddSizeOfResources(MediaSourceDecoder::ResourceSizes* aSizes) const;
+  };
+
+  void CheckSequenceDiscontinuity(const media::TimeUnit& aPresentationTime)
+      MOZ_REQUIRES(mTaskQueueCapability);
+  void ProcessFrames(TrackBuffer& aSamples, TrackData& aTrackData)
+      MOZ_REQUIRES(mTaskQueueCapability);
+  media::TimeInterval PresentationInterval(const TrackBuffer& aSamples) const
+      MOZ_REQUIRES(mTaskQueueCapability);
+  bool CheckNextInsertionIndex(TrackData& aTrackData,
+                               const media::TimeUnit& aSampleTime)
+      MOZ_REQUIRES(mTaskQueueCapability);
+  void InsertFrames(TrackBuffer& aSamples,
+                    const media::TimeIntervals& aIntervals,
+                    TrackData& aTrackData) MOZ_REQUIRES(mTaskQueueCapability);
+  void UpdateHighestTimestamp(TrackData& aTrackData,
+                              const media::TimeUnit& aHighestTime)
+      MOZ_REQUIRES(mTaskQueueCapability);
+  // Remove all frames and their dependencies contained in aIntervals.
+  // Return the index at which frames were first removed or 0 if no frames
+  // removed.
+  enum class RemovalMode {
+    kRemoveFrame,
+    kTruncateFrame,
+  };
+  uint32_t RemoveFrames(const media::TimeIntervals& aIntervals,
+                        TrackData& aTrackData, uint32_t aStartIndex,
+                        RemovalMode aMode);
+  // Recalculate track's evictable amount.
+  void ResetEvictionIndex(TrackData& aTrackData);
+  void UpdateEvictionIndex(TrackData& aTrackData, uint32_t aCurrentIndex);
+  // Find index of sample. Return a negative value if not found.
+  uint32_t FindSampleIndex(const TrackBuffer& aTrackBuffer,
+                           const media::TimeInterval& aInterval);
+  const MediaRawData* GetSample(TrackInfo::TrackType aTrack, uint32_t aIndex,
+                                const media::TimeUnit& aExpectedDts,
+                                const media::TimeUnit& aExpectedPts,
+                                const media::TimeUnit& aFuzz);
+  void UpdateBufferedRanges();
+  void RejectProcessing(const MediaResult& aRejectValue, const char* aName);
+  void ResolveProcessing(bool aResolveValue, const char* aName);
+  MozPromiseRequestHolder<CodedFrameProcessingPromise> mProcessingRequest;
+  MozPromiseHolder<CodedFrameProcessingPromise> mProcessingPromise;
+
+  // Trackbuffers definition.
+  nsTArray<const TrackData*> GetTracksList() const;
+  nsTArray<TrackData*> GetTracksList();
+  TrackData& GetTracksData(TrackType aTrack) {
+    switch (aTrack) {
+      case TrackType::kVideoTrack:
+        return mVideoTracks;
+      case TrackType::kAudioTrack:
+      default:
+        return mAudioTracks;
+    }
+  }
+  const TrackData& GetTracksData(TrackType aTrack) const {
+    switch (aTrack) {
+      case TrackType::kVideoTrack:
+        return mVideoTracks;
+      case TrackType::kAudioTrack:
+      default:
+        return mAudioTracks;
+    }
+  }
+  TrackData mVideoTracks;
+  TrackData mAudioTracks;
+
+  // TaskQueue methods and objects.
+  RefPtr<TaskQueue> GetTaskQueueSafe() const {
+    MutexAutoLock mut(mMutex);
+    return mTaskQueue;
+  }
+  NotNull<AbstractThread*> TaskQueueFromTaskQueue() const {
+#ifdef DEBUG
+    RefPtr<TaskQueue> taskQueue = GetTaskQueueSafe();
+    MOZ_ASSERT(taskQueue && taskQueue->IsCurrentThreadIn());
+#endif
+    return WrapNotNull(mTaskQueue.get());
+  }
+  bool OnTaskQueue() const {
+    auto taskQueue = TaskQueueFromTaskQueue();
+    return taskQueue->IsCurrentThreadIn();
+  }
+  void ResetTaskQueue() {
+    MutexAutoLock mut(mMutex);
+    mTaskQueue = nullptr;
+  }
+
+  // SourceBuffer Queues and running context.
+  SourceBufferTaskQueue mQueue;
+  void QueueTask(SourceBufferTask* aTask);
+  void ProcessTasks();
+  // Set if the TrackBuffersManager is currently processing a task.
+  // At this stage, this task is always a AppendBufferTask.
+  RefPtr<SourceBufferTask> mCurrentTask MOZ_GUARDED_BY(mTaskQueueCapability);
+  // Current SourceBuffer state for ongoing task.
+  // Its content is returned to the SourceBuffer once the AppendBufferTask has
+  // completed.
+  UniquePtr<SourceBufferAttributes> mSourceBufferAttributes
+      MOZ_GUARDED_BY(mTaskQueueCapability);
+  // The current sourcebuffer append window. It's content is equivalent to
+  // mSourceBufferAttributes.mAppendWindowStart/End
+  media::TimeInterval mAppendWindow MOZ_GUARDED_BY(mTaskQueueCapability);
+
+  // Strong references to external objects.
+  nsMainThreadPtrHandle<MediaSourceDecoder> mParentDecoder;
+
+  const RefPtr<AbstractThread> mAbstractMainThread;
+
+  // Return public highest end time across all aTracks.
+  // Monitor must be held.
+  media::TimeUnit HighestEndTime(
+      nsTArray<const media::TimeIntervals*>& aTracks) const;
+
+  // Set to true if mediasource state changed to ended.
+  Atomic<bool> mEnded;
+
+  // Global size of this source buffer content.
+  Atomic<int64_t> mSizeSourceBuffer;
+  const int64_t mVideoEvictionThreshold;
+  const int64_t mAudioEvictionThreshold;
+  enum class EvictionState {
+    NO_EVICTION_NEEDED,
+    EVICTION_NEEDED,
+    EVICTION_COMPLETED,
+  };
+  Atomic<EvictionState> mEvictionState;
+
+  // Monitor to protect following objects accessed across multiple threads.
+  mutable Mutex mMutex MOZ_UNANNOTATED;
+  // mTaskQueue is only ever written after construction on the task queue.
+  // As such, it can be accessed while on task queue without the need for the
+  // mutex.
+  RefPtr<TaskQueue> mTaskQueue;
+  // Stable audio and video track time ranges.
+  media::TimeIntervals mVideoBufferedRanges;
+  media::TimeIntervals mAudioBufferedRanges;
+  // MediaInfo of the first init segment read.
+  MediaInfo mInfo;
+  // End mutex protected members.
+
+  // EventTargetCapability used to ensure we're running on the task queue
+  // as expected for various accesses.
+  // TODO: we could store only this and dispatch to it, rather than also having
+  // mTaskQueue. However, there's special locking around mTaskQueue, so we keep
+  // both for now.
+  Maybe<EventTargetCapability<TaskQueue>> mTaskQueueCapability;
+};
+
+}  // namespace mozilla
+
+#endif /* MOZILLA_TRACKBUFFERSMANAGER_H_ */
diff --git a/dom/media/mediasource/gtest/TestContainerParser.cpp b/dom/media/mediasource/gtest/TestContainerParser.cpp
new file mode 100644
index 0000000000..f3bb6d7eda
--- /dev/null
+++ b/dom/media/mediasource/gtest/TestContainerParser.cpp
@@ -0,0 +1,147 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <gtest/gtest.h>
+#include <stdint.h>
+
+#include "ContainerParser.h"
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/gtest/MozAssertions.h"
+
+using namespace mozilla;
+
+TEST(ContainerParser, MIMETypes)
+{
+  const char* containerTypes[] = {"video/webm", "audio/webm", "video/mp4",
+                                  "audio/mp4", "audio/aac"};
+  UniquePtr<ContainerParser> parser;
+  for (size_t i = 0; i < ArrayLength(containerTypes); ++i) {
+    Maybe<MediaContainerType> containerType =
+        MakeMediaContainerType(containerTypes[i]);
+    ASSERT_TRUE(containerType.isSome());
+    parser = ContainerParser::CreateForMIMEType(*containerType);
+    ASSERT_NE(parser, nullptr);
+  }
+}
+
+already_AddRefed<MediaByteBuffer> make_adts_header() {
+  const uint8_t test[] = {0xff, 0xf1, 0x50, 0x80, 0x03, 0x1f, 0xfc};
+  RefPtr<MediaByteBuffer> buffer(new MediaByteBuffer);
+  buffer->AppendElements(test, ArrayLength(test));
+  return buffer.forget();
+}
+
+TEST(ContainerParser, ADTSHeader)
+{
+  UniquePtr<ContainerParser> parser;
+  parser = ContainerParser::CreateForMIMEType(
+      MediaContainerType(MEDIAMIMETYPE("audio/aac")));
+  ASSERT_NE(parser, nullptr);
+
+  // Audio data should have no gaps.
+  EXPECT_EQ(parser->GetRoundingError(), 0);
+
+  // Test a valid header.
+  RefPtr<MediaByteBuffer> header = make_adts_header();
+  EXPECT_NS_SUCCEEDED(parser->IsInitSegmentPresent(MediaSpan(header)));
+
+  // Test variations.
+  uint8_t save = header->ElementAt(1);
+  for (uint8_t i = 1; i < 3; ++i) {
+    // Set non-zero layer.
+    header->ReplaceElementAt(1, (header->ElementAt(1) & 0xf9) | (i << 1));
+    EXPECT_FALSE(NS_SUCCEEDED(parser->IsInitSegmentPresent(MediaSpan(header))))
+        << "Accepted non-zero layer in header.";
+  }
+  header->ReplaceElementAt(1, save);
+  save = header->ElementAt(2);
+  header->ReplaceElementAt(2, (header->ElementAt(2) & 0x3b) | (15 << 2));
+  EXPECT_FALSE(NS_SUCCEEDED(parser->IsInitSegmentPresent(MediaSpan(header))))
+      << "Accepted explicit frequency in header.";
+  header->ReplaceElementAt(2, save);
+
+  // Test a short header.
+  header->SetLength(6);
+  EXPECT_FALSE(NS_SUCCEEDED(parser->IsInitSegmentPresent(MediaSpan(header))))
+      << "Accepted too-short header.";
+  EXPECT_FALSE(NS_SUCCEEDED(parser->IsMediaSegmentPresent(MediaSpan(header))))
+      << "Found media segment when there was just a partial header.";
+
+  // Test a header with short data.
+  header = make_adts_header();
+  header->AppendElements(1);
+  EXPECT_TRUE(NS_SUCCEEDED(parser->IsInitSegmentPresent(MediaSpan(header))))
+      << "Rejected a valid header.";
+  EXPECT_TRUE(NS_SUCCEEDED(parser->IsMediaSegmentPresent(MediaSpan(header))))
+      << "Rejected a one-byte media segment.";
+
+  // Test parse results.
+  header = make_adts_header();
+  EXPECT_FALSE(NS_SUCCEEDED(parser->IsMediaSegmentPresent(MediaSpan(header))))
+      << "Found media segment when there was just a header.";
+  int64_t start = 0;
+  int64_t end = 0;
+  EXPECT_TRUE(NS_FAILED(
+      parser->ParseStartAndEndTimestamps(MediaSpan(header), start, end)));
+
+  EXPECT_TRUE(parser->HasInitData());
+  EXPECT_TRUE(parser->HasCompleteInitData());
+  MediaByteBuffer* init = parser->InitData();
+  ASSERT_NE(init, nullptr);
+  EXPECT_EQ(init->Length(), header->Length());
+
+  EXPECT_EQ(parser->InitSegmentRange(),
+            MediaByteRange(0, int64_t(header->Length())));
+  // Media segment range should be empty here.
+  EXPECT_EQ(parser->MediaHeaderRange(), MediaByteRange());
+  EXPECT_EQ(parser->MediaSegmentRange(), MediaByteRange());
+}
+
+TEST(ContainerParser, ADTSBlankMedia)
+{
+  UniquePtr<ContainerParser> parser;
+  parser = ContainerParser::CreateForMIMEType(
+      MediaContainerType(MEDIAMIMETYPE("audio/aac")));
+  ASSERT_NE(parser, nullptr);
+
+  // Audio data should have no gaps.
+  EXPECT_EQ(parser->GetRoundingError(), 0);
+
+  // Test the header only.
+  RefPtr<MediaByteBuffer> header = make_adts_header();
+  EXPECT_NS_SUCCEEDED(parser->IsInitSegmentPresent(MediaSpan(header)));
+
+  // Test with the correct length of (invalid) frame data.
+  size_t header_length = header->Length();
+  size_t data_length = 24;
+  size_t frame_length = header_length + data_length;
+  header->AppendElements(data_length);
+  EXPECT_TRUE(NS_SUCCEEDED(parser->IsInitSegmentPresent(MediaSpan(header))))
+      << "Rejected a valid header.";
+  EXPECT_TRUE(NS_SUCCEEDED(parser->IsMediaSegmentPresent(MediaSpan(header))))
+      << "Rejected a full (but zeroed) media segment.";
+  int64_t start = 0;
+  int64_t end = 0;
+  // We don't report timestamps from ADTS.
+  EXPECT_TRUE(NS_FAILED(
+      parser->ParseStartAndEndTimestamps(MediaSpan(header), start, end)));
+  EXPECT_EQ(start, 0);
+  EXPECT_EQ(end, 0);
+
+  // Verify the parser calculated header and packet data boundaries.
+  EXPECT_TRUE(parser->HasInitData());
+  EXPECT_TRUE(parser->HasCompleteInitData());
+  MediaByteBuffer* init = parser->InitData();
+  ASSERT_NE(init, nullptr);
+  EXPECT_EQ(init->Length(), header_length)
+      << "Found incorrect init segment length.";
+  EXPECT_EQ(parser->InitSegmentRange(),
+            MediaByteRange(0, int64_t(header_length)));
+  // In ADTS the Media Header is the same as the Media Segment.
+  MediaByteRange expected_media =
+      MediaByteRange(int64_t(header_length), int64_t(frame_length));
+  EXPECT_EQ(parser->MediaHeaderRange(), expected_media);
+  EXPECT_EQ(parser->MediaSegmentRange(), expected_media);
+}
diff --git a/dom/media/mediasource/gtest/TestExtractAV1CodecDetails.cpp b/dom/media/mediasource/gtest/TestExtractAV1CodecDetails.cpp
new file mode 100644
index 0000000000..8683023204
--- /dev/null
+++ b/dom/media/mediasource/gtest/TestExtractAV1CodecDetails.cpp
@@ -0,0 +1,290 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <gtest/gtest.h>
+#include <stdint.h>
+
+#include "AOMDecoder.h"
+#include "VideoUtils.h"
+
+namespace mozilla {
+void PrintTo(const AOMDecoder::AV1SequenceInfo& aInfo, std::ostream* aStream) {
+  nsAutoCString formatted = nsAutoCString();
+  formatted.AppendPrintf(
+      "av01.%01u.%02u%c.%02u.%01u.%01u%01u%01u.%02u.%02u.%02u.%01u (res: "
+      "%ux%u) operating points: [",
+      aInfo.mProfile, aInfo.mOperatingPoints[0].mLevel,
+      aInfo.mOperatingPoints[0].mTier == 1 ? 'H' : 'M', aInfo.mBitDepth,
+      aInfo.mMonochrome, aInfo.mSubsamplingX, aInfo.mSubsamplingY,
+      static_cast<uint8_t>(aInfo.mChromaSamplePosition),
+      static_cast<uint8_t>(aInfo.mColorSpace.mPrimaries),
+      static_cast<uint8_t>(aInfo.mColorSpace.mTransfer),
+      static_cast<uint8_t>(aInfo.mColorSpace.mMatrix),
+      static_cast<uint8_t>(aInfo.mColorSpace.mRange), aInfo.mImage.Width(),
+      aInfo.mImage.Height());
+  size_t opCount = aInfo.mOperatingPoints.Length();
+  for (size_t i = 0; i < opCount; i++) {
+    const auto& op = aInfo.mOperatingPoints[i];
+    formatted.AppendPrintf("{ layers: %x, level: %u, tier: %u }", op.mLayers,
+                           op.mLevel, op.mTier);
+    if (i != opCount - 1) {
+      formatted.Append(", ");
+    }
+  }
+  formatted.Append("]");
+  *aStream << formatted;
+}
+}  // namespace mozilla
+
+using namespace mozilla;
+
+struct AV1TestData {
+  const char* mCodecParameterString;
+  const bool mExpectedValue;
+  const char* mComment;
+};
+
+TEST(ExtractAV1CodecDetails, TestInputData)
+{
+  AV1TestData tests[] = {
+      // Format is:
+      // av01.N.NN[MH].NN.B.BBN.NN.NN.NN.B
+      // where
+      //   N = decimal digit
+      //   [] = single character
+      //   B = binary digit
+      // Field order:
+      // <sample entry 4CC>.<profile>.<level><tier>.<bitDepth>
+      // [.<monochrome>.<chromaSubsampling>
+      // .<colorPrimaries>.<transferCharacteristics>.<matrixCoefficients>
+      // .<videoFullRangeFlag>]
+
+      // Format checks
+      {"av01.0.10M.08", true, "Minimum length"},
+      {"av1.0.10M.08", false, "Invalid 4CC"},
+      {"av01..10M.08", false, "Blank field"},
+      {"av01.-1.10M.08", false, "Negative field"},
+      {"av01.0.10M.8", false, "Missing leading zeros"},
+
+      // Field counts
+      {"av01", false, "0 of 4 required fields"},
+      {"av01.0", false, "1 of 4 required fields"},
+      {"av01.0.10", false, "2 of 4 required fields"},
+      {"av01.0.10M", false, "3 of 4 required fields"},
+      {"av01.0.10M.08.0", false, "5 fields, AV1 requires 4 or 10"},
+      {"av01.0.10M.08.0.110.01.01.01", false, "9 fields, AV1 requires 4 or 10"},
+      {"av01.0.10M.08.0.110.01.01.01.0", true, "Maximum fields"},
+      {"av01.0.10M.08.0.110.01.01.01.0.0", false, "Too many fields"},
+
+      // "Comments" are allowed (unknown characters at the end of fields)
+      {"av01.0.10M.08this is ignored", true, "Minimum length with comment"},
+      {"av01.0.10Mbad comment", false, "Comment before required field"},
+      {"av01.0.10M.08.0.110.01.01.01.0also ignored", true,
+       "Maximum length with comment"},
+
+      // Begin field checks
+
+      // -- Profile --
+      // Main Profile (0) tested above
+
+      // High Profile requires 4:4:4 chroma subsampling without monochrome
+      {"av01.1.10M.08", false, "High Profile (1) without parameters"},
+      {"av01.1.10M.08.0.000.01.01.01.0", true, "High Profile (1)"},
+
+      // Professional requires either of:
+      // - 8bit or 10bit at 4:2:2
+      // - 12bit at any subsampling
+      {"av01.2.10M.10.0.100.01.01.01.0", true,
+       "Professional Profile (2) 10-bit 4:2:2"},
+      {"av01.2.10M.12.0.110.01.01.01.0", true,
+       "Professional Profile (2) 12-bit 4:2:0"},
+
+      {"av01.3.10M.12.0.000.01.01.01.0", false, "Invalid Profile 3"},
+
+      // -- Level --
+      {"av01.0.00M.08", true, "Level 0 (2.1)"},
+      // Level 4.2 (10) tested above
+      {"av01.0.14M.08", true, "Level 14 (5.2)"},
+      {"av01.0.23M.08", true, "Level 23 (7.3)"},
+      {"av01.0.24M.08", false, "Level 24 (Reserved)"},
+
+      // -- Tier --
+      // Main tier tested above
+      {"av01.0.10H.08", true, "High tier"},
+
+      // -- Bit depth --
+      // 8-bit tested above with Main and High Profiles
+      {"av01.0.10M.10", true, "Main 10-bit"},
+      {"av01.1.10M.10.0.000.01.01.01.0", true, "High 10-bit"},
+      {"av01.1.10M.12.0.000.01.01.01.0", false, "High 12-bit (Invalid)"},
+      // Valid 12-bit tested for Professional Profile
+
+      // -- Monochrome --
+      // Monochrome off tested above
+      {"av01.0.10M.08.1.110.01.01.01.0", true, "Main 8-bit monochrome"},
+      {"av01.1.10M.10.1.000.01.01.01.0", false,
+       "4:4:4 is incompatible with monochrome"},
+      {"av01.2.10M.10.1.100.01.01.01.0", false,
+       "4:2:0 is incompatible with monochrome"},
+      {"av01.2.10M.12.1.110.01.01.01.0", true,
+       "Professional 12-bit monochrome"},
+
+      // -- Chroma subsampling --
+      // Field is parsed by digits <x><y><position>
+      // where positions are [unknown, vertical, colocated]
+      {"av01.0.10M.08.0.112.01.01.01.0", true, "Chroma colocated"},
+      // Main Profile, 4:2:0 tested above
+      {"av01.0.10M.08.0.100.01.01.01.0", false,
+       "4:2:2 not allowed on Main Profile"},
+      // High Profile, 4:4:4 tested above
+      {"av01.1.10M.08.0.110.01.01.01.0", false,
+       "4:4:4 required on High Profile"},
+      {"av01.2.10M.08.0.110.01.01.01.0", false,
+       "4:2:0 not allowed on 8-bit Professional"},
+      // Professional Profile, 8-bit 4:2:2 tested above
+      // Professional Profile, 12-bit 4:2:0 tested above
+      {"av01.2.10M.12.0.100.01.01.01.0", true, "12-bit 4:2:2"},
+      {"av01.2.10M.12.0.000.01.01.01.0", true, "12-bit 4:4:4"},
+
+      {"av01.2.10M.08.0.101.01.01.01.0", false, "Chroma position with 4:2:2"},
+      {"av01.1.10M.08.0.001.01.01.01.0", false, "Chroma position with 4:4:4"},
+      {"av01.0.10M.08.0.113.01.01.01.0", false, "Chroma position 3 (Reserved)"},
+
+      // -- Color primaries --
+      // 0, 3, [13-21], >23 are reserved
+      // 1 (BT709) is tested above
+      {"av01.0.10M.10.0.110.09.16.09.0", true,
+       "Color space: BT2020/SMPTE2084/BT2020NCL"},
+      {"av01.0.10M.10.0.110.00.16.09.0", false, "Primaries 0: Reserved"},
+      {"av01.0.10M.10.0.110.03.16.09.0", false, "Primaries 3: Reserved"},
+      {"av01.0.10M.10.0.110.13.16.09.0", false, "Primaries 13: Reserved"},
+      {"av01.0.10M.10.0.110.21.16.09.0", false, "Primaries 21: Reserved"},
+      {"av01.0.10M.10.0.110.22.16.09.0", true, "Primaries 22: EBU3213"},
+      {"av01.0.10M.10.0.110.23.16.09.0", false, "Primaries 23: Reserved"},
+
+      // -- Transfer characteristics --
+      // 0, 3, >19 are all reserved
+      // 1 (BT709) is tested above
+      // 16 (SMPTE2084) is tested above
+      {"av01.0.10M.10.0.110.09.14.09.0", true,
+       "Color space: BT2020/BT2020 10-bit/BT2020NCL"},
+      {"av01.0.10M.10.0.110.09.00.09.0", false, "Transfer 0: Reserved"},
+      {"av01.0.10M.10.0.110.09.03.09.0", false, "Transfer 3: Reserved"},
+      {"av01.0.10M.10.0.110.09.20.09.0", false, "Transfer 20: Reserved"},
+
+      // -- Matrix coefficients --
+      // 3, >15 are all reserved
+      // 1 (BT709) is tested above
+      // 9 (BT2020NCL) is tested above
+      {"av01.1.10M.10.0.000.01.13.00.1", true, "4:4:4 10-bit sRGB"},
+      {"av01.1.10M.10.0.000.01.13.00.0", false, "sRGB requires full range"},
+      {"av01.2.10M.10.0.100.01.13.00.1", false,
+       "Subsampling incompatible with sRGB"},
+      {"av01.2.10M.12.0.000.01.13.00.1", true, "4:4:4 12-bit sRGB"},
+      {"av01.2.10M.12.0.000.01.01.15.1", false, "Matrix 15: Reserved"},
+
+      // -- Color range --
+      // Full range and limited range tested above
+      {"av01.0.10M.12.0.002.01.13.00.2", false, "Color range 2 invalid"},
+  };
+
+  for (const auto& data : tests) {
+    auto info = AOMDecoder::CreateSequenceInfoFromCodecs(
+        NS_ConvertUTF8toUTF16(data.mCodecParameterString));
+    nsAutoCString desc = nsAutoCString(data.mCodecParameterString,
+                                       strlen(data.mCodecParameterString));
+    desc.AppendLiteral(" (");
+    desc.Append(data.mComment, strlen(data.mComment));
+    desc.AppendLiteral(")");
+    EXPECT_EQ(info.isSome(), data.mExpectedValue) << desc;
+
+    if (info.isSome()) {
+      AOMDecoder::AV1SequenceInfo inputInfo = info.value();
+      inputInfo.mImage = gfx::IntSize(1920, 1080);
+      RefPtr<MediaByteBuffer> buffer = new MediaByteBuffer();
+      bool wroteSequenceHeader;
+      AOMDecoder::WriteAV1CBox(inputInfo, buffer, wroteSequenceHeader);
+      EXPECT_EQ(wroteSequenceHeader, data.mExpectedValue) << desc;
+      // Read equality test will fail also, don't clutter.
+      if (!wroteSequenceHeader) {
+        continue;
+      }
+      AOMDecoder::AV1SequenceInfo parsedInfo;
+      bool readSequenceHeader;
+      AOMDecoder::ReadAV1CBox(buffer, parsedInfo, readSequenceHeader);
+      EXPECT_EQ(wroteSequenceHeader, readSequenceHeader) << desc;
+      EXPECT_EQ(inputInfo, parsedInfo) << desc;
+    }
+  }
+}
+
+TEST(ExtractAV1CodecDetails, TestParsingOutput)
+{
+  auto info = AOMDecoder::CreateSequenceInfoFromCodecs(
+      nsString(u"av01.0.14M.08.0.112.01.01.01.0"));
+  EXPECT_TRUE(info.isSome());
+
+  if (info.isSome()) {
+    EXPECT_EQ(info->mProfile, 0u);
+    EXPECT_EQ(info->mOperatingPoints.Length(), 1u);
+    EXPECT_EQ(info->mOperatingPoints[0].mLayers, 0u);
+    EXPECT_EQ(info->mOperatingPoints[0].mLevel, 14u);
+    EXPECT_EQ(info->mOperatingPoints[0].mTier, 0u);
+    EXPECT_EQ(info->mBitDepth, 8u);
+    EXPECT_EQ(info->mMonochrome, false);
+    EXPECT_EQ(info->mSubsamplingX, true);
+    EXPECT_EQ(info->mSubsamplingY, true);
+    EXPECT_EQ(info->mChromaSamplePosition,
+              AOMDecoder::ChromaSamplePosition::Colocated);
+    EXPECT_EQ(info->mColorSpace.mPrimaries, gfx::CICP::CP_BT709);
+    EXPECT_EQ(info->mColorSpace.mTransfer, gfx::CICP::TC_BT709);
+    EXPECT_EQ(info->mColorSpace.mMatrix, gfx::CICP::MC_BT709);
+    EXPECT_EQ(info->mColorSpace.mRange, gfx::ColorRange::LIMITED);
+  }
+
+  info = AOMDecoder::CreateSequenceInfoFromCodecs(
+      nsString(u"av01.1.11H.10.0.000.07.07.07.1"));
+  EXPECT_TRUE(info.isSome());
+
+  if (info.isSome()) {
+    EXPECT_EQ(info->mProfile, 1u);
+    EXPECT_EQ(info->mOperatingPoints.Length(), 1u);
+    EXPECT_EQ(info->mOperatingPoints[0].mLayers, 0u);
+    EXPECT_EQ(info->mOperatingPoints[0].mLevel, 11u);
+    EXPECT_EQ(info->mOperatingPoints[0].mTier, 1u);
+    EXPECT_EQ(info->mBitDepth, 10u);
+    EXPECT_EQ(info->mMonochrome, false);
+    EXPECT_EQ(info->mSubsamplingX, false);
+    EXPECT_EQ(info->mSubsamplingY, false);
+    EXPECT_EQ(info->mChromaSamplePosition,
+              AOMDecoder::ChromaSamplePosition::Unknown);
+    EXPECT_EQ(info->mColorSpace.mPrimaries, gfx::CICP::CP_SMPTE240);
+    EXPECT_EQ(info->mColorSpace.mTransfer, gfx::CICP::TC_SMPTE240);
+    EXPECT_EQ(info->mColorSpace.mMatrix, gfx::CICP::MC_SMPTE240);
+    EXPECT_EQ(info->mColorSpace.mRange, gfx::ColorRange::FULL);
+  }
+
+  info = AOMDecoder::CreateSequenceInfoFromCodecs(
+      nsString(u"av01.2.22H.12.1.110.10.08.04.1"));
+  EXPECT_TRUE(info.isSome());
+
+  if (info.isSome()) {
+    EXPECT_EQ(info->mProfile, 2u);
+    EXPECT_EQ(info->mOperatingPoints.Length(), 1u);
+    EXPECT_EQ(info->mOperatingPoints[0].mLayers, 0u);
+    EXPECT_EQ(info->mOperatingPoints[0].mLevel, 22u);
+    EXPECT_EQ(info->mOperatingPoints[0].mTier, 1u);
+    EXPECT_EQ(info->mBitDepth, 12u);
+    EXPECT_EQ(info->mMonochrome, true);
+    EXPECT_EQ(info->mSubsamplingX, true);
+    EXPECT_EQ(info->mSubsamplingY, true);
+    EXPECT_EQ(info->mChromaSamplePosition,
+              AOMDecoder::ChromaSamplePosition::Unknown);
+    EXPECT_EQ(info->mColorSpace.mPrimaries, gfx::CICP::CP_XYZ);
+    EXPECT_EQ(info->mColorSpace.mTransfer, gfx::CICP::TC_LINEAR);
+    EXPECT_EQ(info->mColorSpace.mMatrix, gfx::CICP::MC_FCC);
+    EXPECT_EQ(info->mColorSpace.mRange, gfx::ColorRange::FULL);
+  }
+}
diff --git a/dom/media/mediasource/gtest/TestExtractVPXCodecDetails.cpp b/dom/media/mediasource/gtest/TestExtractVPXCodecDetails.cpp
new file mode 100644
index 0000000000..7e255e2dc7
--- /dev/null
+++ b/dom/media/mediasource/gtest/TestExtractVPXCodecDetails.cpp
@@ -0,0 +1,141 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <gtest/gtest.h>
+#include <stdint.h>
+
+#include "VideoUtils.h"
+
+using namespace mozilla;
+
+struct TestData {
+  const char16_t* const mCodecParameterString;
+  const bool mExpectedValue;
+  const char* const mComment;
+};
+
+TEST(ExtractVPXCodecDetails, TestInputData)
+{
+  TestData tests[] = {
+      // <sample entry 4CC>.<profile>.<level>.<bitDepth>.<chromaSubsampling>.
+      // <colourPrimaries>.<transferCharacteristics>.<matrixCoefficients>.
+      // <videoFullRangeFlag>
+
+      // Format checks
+      {u"vp09.0.10.8", true, "Valid minimum length"},
+      {u"vp9.00.10.08", false, "Invalid 4CC"},
+      {u"vp09.00..08", false, "Blank field"},
+      {u"vp09", false, "0 of 3 required fields"},
+      {u"vp09.00", false, "1 of 3 required fields"},
+      {u"vp09.00.10", false, "2 of 3 required fields"},
+
+      // Profiles
+      {u"vp09.00.10.08", true, "Profile 0"},
+      {u"vp09.01.10.08", true, "Profile 1"},
+      {u"vp09.02.10.10", true, "Profile 2"},
+      {u"vp09.03.10.10", true, "Profile 3"},
+      {u"vp09.-1.10.08", false, "Invalid profile < 0"},
+      {u"vp09.04.10.08", false, "Invalid profile > 3"},
+
+      // Levels
+      {u"vp09.00.11.08", true, "Level 1.1"},
+      {u"vp09.00.12.08", false, "Invalid level 1.2"},
+      {u"vp09.00.52.08", true, "Level 5.2"},
+      {u"vp09.00.64.08", false, "Level greater than max"},
+
+      // Bit depths
+      // - 8-bit tested in Profiles section
+      // - 10-bit tested in Profiles section
+      {u"vp09.02.10.12", true, "12-bit"},
+      {u"vp09.00.10.07", false, "Invalid, 7-bit"},
+      {u"vp09.02.10.11", false, "Invalid, 11-bit"},
+      {u"vp09.02.10.13", false, "Invalid, 13-bit"},
+
+      // Chroma subsampling
+      {u"vp09.00.10.08.00", true, "4:2:0 vertical"},
+      {u"vp09.00.10.08.01", true, "4:2:0 colocated"},
+      {u"vp09.00.10.08.02", true, "4:2:2"},
+      {u"vp09.00.10.08.03", true, "4:4:4"},
+      {u"vp09.00.10.08.04", false, "Invalid chroma"},
+
+      // Color primaries
+      {u"vp09.00.10.08.01.00", false, "CP 0: Reserved"},
+      {u"vp09.00.10.08.01.01", true, "CP 1: BT.709"},
+      {u"vp09.00.10.08.01.03", false, "CP 3: Reserved"},
+      {u"vp09.00.10.08.01.09", true, "CP 9: BT.2020"},
+      {u"vp09.00.10.08.01.21", false, "CP 21: Reserved"},
+      {u"vp09.00.10.08.01.22", true, "CP 22: EBU Tech 3213"},
+      {u"vp09.00.10.08.01.23", false, "CP 23: Out of range"},
+
+      // Transfer characteristics
+      {u"vp09.00.10.08.01.01.00", false, "TC 0: Reserved"},
+      {u"vp09.00.10.08.01.01.01", true, "TC 1: BT.709"},
+      {u"vp09.00.10.08.01.01.03", false, "TC 3: Reserved"},
+      {u"vp09.00.10.08.01.09.16", true, "TC 16: ST 2084"},
+      {u"vp09.00.10.08.01.09.19", false, "TC 19: Out of range"},
+
+      // Matrix coefficients
+      {u"vp09.00.10.08.03.09.16.00", true, "MC 0: Identity"},
+      {u"vp09.00.10.08.01.09.16.00", false, "MC 0: Identity without 4:4:4"},
+      {u"vp09.00.10.08.01.09.16.01", true, "MC 1: BT.709"},
+      {u"vp09.00.10.08.01.09.16.03", false, "MC 3: Reserved"},
+      {u"vp09.00.10.08.01.09.16.09", true, "MC 9: BT.2020"},
+      {u"vp09.00.10.08.01.09.16.15", false, "MC 15: Out of range"},
+
+      // Color range
+      {u"vp09.00.10.08.01.09.16.09.00", true, "Limited range"},
+      {u"vp09.00.10.08.01.09.16.09.01", true, "Full range"},
+      {u"vp09.00.10.08.01.09.16.09.02", false, "Invalid range value"},
+
+      {u"vp09.00.10.08.01.09.16.09.00.", false, "Extra ."},
+      {u"vp09.00.10.08.01.09.16.09.00.00", false, "More than 9 fields"},
+  };
+
+  for (const auto& data : tests) {
+    uint8_t profile = 0;
+    uint8_t level = 0;
+    uint8_t bitDepth = 0;
+    bool result = ExtractVPXCodecDetails(nsString(data.mCodecParameterString),
+                                         profile, level, bitDepth);
+    EXPECT_EQ(result, data.mExpectedValue)
+        << NS_ConvertUTF16toUTF8(data.mCodecParameterString).get() << " ("
+        << data.mComment << ")";
+  }
+}
+
+TEST(ExtractVPXCodecDetails, TestParsingOutput)
+{
+  uint8_t profile = 0;
+  uint8_t level = 0;
+  uint8_t bitDepth = 0;
+  uint8_t chromaSubsampling = 0;
+  VideoColorSpace colorSpace;
+  auto data = u"vp09.01.11.08";
+  bool result = ExtractVPXCodecDetails(nsString(data), profile, level, bitDepth,
+                                       chromaSubsampling, colorSpace);
+  EXPECT_EQ(result, true);
+  EXPECT_EQ(profile, 1);
+  EXPECT_EQ(level, 11);
+  EXPECT_EQ(bitDepth, 8);
+  // Should keep spec defined default value.
+  EXPECT_EQ(chromaSubsampling, 1);
+  EXPECT_EQ(colorSpace.mPrimaries, gfx::CICP::CP_BT709);
+  EXPECT_EQ(colorSpace.mTransfer, gfx::CICP::TC_BT709);
+  EXPECT_EQ(colorSpace.mMatrix, gfx::CICP::MC_BT709);
+  EXPECT_EQ(colorSpace.mRange, gfx::ColorRange::LIMITED);
+
+  data = u"vp09.02.10.10.01.09.16.09.01";
+  result = ExtractVPXCodecDetails(nsString(data), profile, level, bitDepth,
+                                  chromaSubsampling, colorSpace);
+  EXPECT_EQ(result, true);
+  EXPECT_EQ(profile, 2);
+  EXPECT_EQ(level, 10);
+  EXPECT_EQ(bitDepth, 10);
+  EXPECT_EQ(chromaSubsampling, 1);
+  EXPECT_EQ(colorSpace.mPrimaries, gfx::CICP::CP_BT2020);
+  EXPECT_EQ(colorSpace.mTransfer, gfx::CICP::TC_SMPTE2084);
+  EXPECT_EQ(colorSpace.mMatrix, gfx::CICP::MC_BT2020_NCL);
+  EXPECT_EQ(colorSpace.mRange, gfx::ColorRange::FULL);
+}
diff --git a/dom/media/mediasource/gtest/moz.build b/dom/media/mediasource/gtest/moz.build
new file mode 100644
index 0000000000..42ef6beb9b
--- /dev/null
+++ b/dom/media/mediasource/gtest/moz.build
@@ -0,0 +1,22 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+UNIFIED_SOURCES += [
+    "TestContainerParser.cpp",
+    "TestExtractVPXCodecDetails.cpp",
+]
+
+if CONFIG["MOZ_AV1"]:
+    UNIFIED_SOURCES += [
+        "TestExtractAV1CodecDetails.cpp",
+    ]
+
+LOCAL_INCLUDES += [
+    "/dom/media",
+    "/dom/media/mediasource",
+]
+
+FINAL_LIBRARY = "xul-gtest"
diff --git a/dom/media/mediasource/moz.build b/dom/media/mediasource/moz.build
new file mode 100644
index 0000000000..3fa98e42b7
--- /dev/null
+++ b/dom/media/mediasource/moz.build
@@ -0,0 +1,42 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+MOCHITEST_MANIFESTS += ["test/mochitest.ini"]
+
+EXPORTS += [
+    "AsyncEventRunner.h",
+    "MediaSourceDecoder.h",
+    "MediaSourceDemuxer.h",
+    "SourceBufferAttributes.h",
+    "SourceBufferTask.h",
+    "TrackBuffersManager.h",
+]
+
+EXPORTS.mozilla.dom += [
+    "MediaSource.h",
+    "SourceBuffer.h",
+    "SourceBufferList.h",
+]
+
+UNIFIED_SOURCES += [
+    "ContainerParser.cpp",
+    "MediaSource.cpp",
+    "MediaSourceDecoder.cpp",
+    "MediaSourceDemuxer.cpp",
+    "MediaSourceUtils.cpp",
+    "ResourceQueue.cpp",
+    "SourceBuffer.cpp",
+    "SourceBufferList.cpp",
+    "SourceBufferResource.cpp",
+    "TrackBuffersManager.cpp",
+]
+
+TEST_DIRS += [
+    "gtest",
+]
+
+include("/ipc/chromium/chromium-config.mozbuild")
+
+FINAL_LIBRARY = "xul"
diff --git a/dom/media/mediasource/test/.eslintrc.js b/dom/media/mediasource/test/.eslintrc.js
new file mode 100644
index 0000000000..e283e384ba
--- /dev/null
+++ b/dom/media/mediasource/test/.eslintrc.js
@@ -0,0 +1,28 @@
+"use strict";
+
+module.exports = {
+  // Globals from mediasource.js. We use false to indicate they should not
+  // be overwritten in scripts.
+  globals: {
+    addMSEPrefs: false,
+    fetchAndLoad: false,
+    fetchAndLoadAsync: false,
+    fetchWithXHR: false,
+    logEvents: false,
+    loadSegment: false,
+    must_not_reject: false,
+    must_not_throw: false,
+    must_reject: false,
+    must_throw: false,
+    once: false,
+    range: false,
+    runWithMSE: false,
+    wait: false,
+    waitUntilTime: false,
+  },
+  // Use const/let instead of var for tighter scoping, avoiding redeclaration
+  rules: {
+    "no-var": "error",
+    "prefer-const": "error",
+  },
+};
diff --git a/dom/media/mediasource/test/1516754.webm b/dom/media/mediasource/test/1516754.webm
new file mode 100644
index 0000000000..05a008d906
--- /dev/null
+++ b/dom/media/mediasource/test/1516754.webm
diff --git a/dom/media/mediasource/test/1516754.webm^headers^ b/dom/media/mediasource/test/1516754.webm^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/1516754.webm^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/aac20-48000-64000-1.m4s b/dom/media/mediasource/test/aac20-48000-64000-1.m4s
new file mode 100644
index 0000000000..56506e1f2d
--- /dev/null
+++ b/dom/media/mediasource/test/aac20-48000-64000-1.m4s
diff --git a/dom/media/mediasource/test/aac20-48000-64000-1.m4s^headers^ b/dom/media/mediasource/test/aac20-48000-64000-1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/aac20-48000-64000-1.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/aac20-48000-64000-2.m4s b/dom/media/mediasource/test/aac20-48000-64000-2.m4s
new file mode 100644
index 0000000000..3faff17ebf
--- /dev/null
+++ b/dom/media/mediasource/test/aac20-48000-64000-2.m4s
diff --git a/dom/media/mediasource/test/aac20-48000-64000-2.m4s^headers^ b/dom/media/mediasource/test/aac20-48000-64000-2.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/aac20-48000-64000-2.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/aac20-48000-64000-init.mp4 b/dom/media/mediasource/test/aac20-48000-64000-init.mp4
new file mode 100644
index 0000000000..b70e016512
--- /dev/null
+++ b/dom/media/mediasource/test/aac20-48000-64000-init.mp4
diff --git a/dom/media/mediasource/test/aac20-48000-64000-init.mp4^headers^ b/dom/media/mediasource/test/aac20-48000-64000-init.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/aac20-48000-64000-init.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/aac51-48000-128000-1.m4s b/dom/media/mediasource/test/aac51-48000-128000-1.m4s
new file mode 100644
index 0000000000..3424acfecc
--- /dev/null
+++ b/dom/media/mediasource/test/aac51-48000-128000-1.m4s
diff --git a/dom/media/mediasource/test/aac51-48000-128000-1.m4s^headers^ b/dom/media/mediasource/test/aac51-48000-128000-1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/aac51-48000-128000-1.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/aac51-48000-128000-2.m4s b/dom/media/mediasource/test/aac51-48000-128000-2.m4s
new file mode 100644
index 0000000000..b02bfd043d
--- /dev/null
+++ b/dom/media/mediasource/test/aac51-48000-128000-2.m4s
diff --git a/dom/media/mediasource/test/aac51-48000-128000-2.m4s^headers^ b/dom/media/mediasource/test/aac51-48000-128000-2.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/aac51-48000-128000-2.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/aac51-48000-128000-init.mp4 b/dom/media/mediasource/test/aac51-48000-128000-init.mp4
new file mode 100644
index 0000000000..7d62401f28
--- /dev/null
+++ b/dom/media/mediasource/test/aac51-48000-128000-init.mp4
diff --git a/dom/media/mediasource/test/aac51-48000-128000-init.mp4^headers^ b/dom/media/mediasource/test/aac51-48000-128000-init.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/aac51-48000-128000-init.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/avc3/init.mp4 b/dom/media/mediasource/test/avc3/init.mp4
new file mode 100644
index 0000000000..12fc38bd20
--- /dev/null
+++ b/dom/media/mediasource/test/avc3/init.mp4
diff --git a/dom/media/mediasource/test/avc3/init.mp4^headers^ b/dom/media/mediasource/test/avc3/init.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/avc3/init.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/avc3/segment1.m4s b/dom/media/mediasource/test/avc3/segment1.m4s
new file mode 100644
index 0000000000..d95a6adf02
--- /dev/null
+++ b/dom/media/mediasource/test/avc3/segment1.m4s
diff --git a/dom/media/mediasource/test/avc3/segment1.m4s^headers^ b/dom/media/mediasource/test/avc3/segment1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/avc3/segment1.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop1.m4s b/dom/media/mediasource/test/bipbop/bipbop1.m4s
new file mode 100644
index 0000000000..a237f2e91e
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop1.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop1.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop1.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop10.m4s b/dom/media/mediasource/test/bipbop/bipbop10.m4s
new file mode 100644
index 0000000000..d1f5e6a0b0
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop10.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop10.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop10.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop10.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop11.m4s b/dom/media/mediasource/test/bipbop/bipbop11.m4s
new file mode 100644
index 0000000000..57232fb359
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop11.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop11.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop11.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop11.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop12.m4s b/dom/media/mediasource/test/bipbop/bipbop12.m4s
new file mode 100644
index 0000000000..f9b18713ee
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop12.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop12.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop12.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop12.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop13.m4s b/dom/media/mediasource/test/bipbop/bipbop13.m4s
new file mode 100644
index 0000000000..f2a876946c
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop13.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop13.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop13.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop13.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop2.m4s b/dom/media/mediasource/test/bipbop/bipbop2.m4s
new file mode 100644
index 0000000000..baa0d8578c
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop2.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop2.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop2.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop2.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop2s.mp4 b/dom/media/mediasource/test/bipbop/bipbop2s.mp4
new file mode 100644
index 0000000000..4fd8b9cb6e
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop2s.mp4
diff --git a/dom/media/mediasource/test/bipbop/bipbop2s.mp4^headers^ b/dom/media/mediasource/test/bipbop/bipbop2s.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop2s.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop3.m4s b/dom/media/mediasource/test/bipbop/bipbop3.m4s
new file mode 100644
index 0000000000..ed313e668c
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop3.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop3.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop3.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop3.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop4.m4s b/dom/media/mediasource/test/bipbop/bipbop4.m4s
new file mode 100644
index 0000000000..7709ac08c5
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop4.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop4.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop4.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop4.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop5.m4s b/dom/media/mediasource/test/bipbop/bipbop5.m4s
new file mode 100644
index 0000000000..6d36788e44
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop5.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop5.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop5.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop5.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop6.m4s b/dom/media/mediasource/test/bipbop/bipbop6.m4s
new file mode 100644
index 0000000000..64f475c700
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop6.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop6.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop6.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop6.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop7.m4s b/dom/media/mediasource/test/bipbop/bipbop7.m4s
new file mode 100644
index 0000000000..c148918d6d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop7.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop7.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop7.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop7.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop8.m4s b/dom/media/mediasource/test/bipbop/bipbop8.m4s
new file mode 100644
index 0000000000..707dd48485
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop8.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop8.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop8.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop8.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop9.m4s b/dom/media/mediasource/test/bipbop/bipbop9.m4s
new file mode 100644
index 0000000000..538cf72a4d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop9.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop9.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop9.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop9.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_300-3s.webm b/dom/media/mediasource/test/bipbop/bipbop_300-3s.webm
new file mode 100644
index 0000000000..db578dc96c
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_300-3s.webm
diff --git a/dom/media/mediasource/test/bipbop/bipbop_300-3s.webm^headers^ b/dom/media/mediasource/test/bipbop/bipbop_300-3s.webm^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_300-3s.webm^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_480_624kbps-video1.m4s b/dom/media/mediasource/test/bipbop/bipbop_480_624kbps-video1.m4s
new file mode 100644
index 0000000000..3dad336e8e
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_480_624kbps-video1.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_480_624kbps-video1.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_480_624kbps-video1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_480_624kbps-video1.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_480_624kbps-video2.m4s b/dom/media/mediasource/test/bipbop/bipbop_480_624kbps-video2.m4s
new file mode 100644
index 0000000000..dd7491241f
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_480_624kbps-video2.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_480_624kbps-video2.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_480_624kbps-video2.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_480_624kbps-video2.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_480_624kbps-videoinit.mp4 b/dom/media/mediasource/test/bipbop/bipbop_480_624kbps-videoinit.mp4
new file mode 100644
index 0000000000..b1a2d44058
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_480_624kbps-videoinit.mp4
diff --git a/dom/media/mediasource/test/bipbop/bipbop_480_624kbps-videoinit.mp4^headers^ b/dom/media/mediasource/test/bipbop/bipbop_480_624kbps-videoinit.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_480_624kbps-videoinit.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio1.m4s b/dom/media/mediasource/test/bipbop/bipbop_audio1.m4s
new file mode 100644
index 0000000000..33da98b5a9
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio1.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio1.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_audio1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio1.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio10.m4s b/dom/media/mediasource/test/bipbop/bipbop_audio10.m4s
new file mode 100644
index 0000000000..36a98afd29
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio10.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio10.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_audio10.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio10.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio11.m4s b/dom/media/mediasource/test/bipbop/bipbop_audio11.m4s
new file mode 100644
index 0000000000..23d4aa8d86
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio11.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio11.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_audio11.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio11.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio2.m4s b/dom/media/mediasource/test/bipbop/bipbop_audio2.m4s
new file mode 100644
index 0000000000..96f4bcc344
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio2.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio2.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_audio2.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio2.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio3.m4s b/dom/media/mediasource/test/bipbop/bipbop_audio3.m4s
new file mode 100644
index 0000000000..7de4bd0ca1
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio3.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio3.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_audio3.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio3.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio4.m4s b/dom/media/mediasource/test/bipbop/bipbop_audio4.m4s
new file mode 100644
index 0000000000..494c71eb92
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio4.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio4.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_audio4.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio4.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio5.m4s b/dom/media/mediasource/test/bipbop/bipbop_audio5.m4s
new file mode 100644
index 0000000000..b50496b6ce
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio5.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio5.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_audio5.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio5.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio6.m4s b/dom/media/mediasource/test/bipbop/bipbop_audio6.m4s
new file mode 100644
index 0000000000..02cf4d363c
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio6.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio6.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_audio6.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio6.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio7.m4s b/dom/media/mediasource/test/bipbop/bipbop_audio7.m4s
new file mode 100644
index 0000000000..bb2252889f
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio7.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio7.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_audio7.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio7.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio8.m4s b/dom/media/mediasource/test/bipbop/bipbop_audio8.m4s
new file mode 100644
index 0000000000..04a6a7af91
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio8.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio8.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_audio8.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio8.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio9.m4s b/dom/media/mediasource/test/bipbop/bipbop_audio9.m4s
new file mode 100644
index 0000000000..cb94b529a7
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio9.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audio9.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_audio9.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audio9.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audioinit.mp4 b/dom/media/mediasource/test/bipbop/bipbop_audioinit.mp4
new file mode 100644
index 0000000000..bbf272197d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audioinit.mp4
diff --git a/dom/media/mediasource/test/bipbop/bipbop_audioinit.mp4^headers^ b/dom/media/mediasource/test/bipbop/bipbop_audioinit.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_audioinit.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_dash.mpd b/dom/media/mediasource/test/bipbop/bipbop_dash.mpd
new file mode 100644
index 0000000000..532cdc65d5
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_dash.mpd
@@ -0,0 +1,48 @@
+<?xml version="1.0"?>
+<MPD xmlns="urn:mpeg:dash:schema:mpd:2011" minBufferTime="PT1.500000S" type="static" mediaPresentationDuration="PT0H0M9.98S" profiles="urn:mpeg:dash:profile:full:2011">
+ <ProgramInformation moreInformationURL="http://gpac.sourceforge.net">
+  <Title>bipbop_dash.mpd handcrafted by JYA</Title>
+ </ProgramInformation>
+
+ <Period duration="PT0H0M9.98S">
+  <AdaptationSet segmentAlignment="true" maxWidth="400" maxHeight="300" maxFrameRate="90000" par="4:3" lang="und">
+   <Representation id="1" mimeType="video/mp4" codecs="avc1.4d4015" width="400" height="300" frameRate="90000" sar="1:1" startWithSAP="1" bandwidth="226425">
+    <SegmentList timescale="90000" duration="69043">
+     <Initialization sourceURL="bipbop_videoinit.mp4"/>
+     <SegmentURL media="bipbop_video1.m4s"/>
+     <SegmentURL media="bipbop_video2.m4s"/>
+     <SegmentURL media="bipbop_video3.m4s"/>
+     <SegmentURL media="bipbop_video4.m4s"/>
+     <SegmentURL media="bipbop_video5.m4s"/>
+     <SegmentURL media="bipbop_video6.m4s"/>
+     <SegmentURL media="bipbop_video7.m4s"/>
+     <SegmentURL media="bipbop_video8.m4s"/>
+     <SegmentURL media="bipbop_video9.m4s"/>
+     <SegmentURL media="bipbop_video10.m4s"/>
+     <SegmentURL media="bipbop_video11.m4s"/>
+     <SegmentURL media="bipbop_video12.m4s"/>
+     <SegmentURL media="bipbop_video13.m4s"/>
+    </SegmentList>
+   </Representation>
+  </AdaptationSet>
+  <AdaptationSet segmentAlignment="true" lang="und">
+   <Representation id="1" mimeType="audio/mp4" codecs="mp4a.40.2" audioSamplingRate="22050" startWithSAP="1" bandwidth="7206">
+    <AudioChannelConfiguration schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"/>
+    <SegmentList timescale="22050" duration="20101">
+     <Initialization sourceURL="bipbop_audioinit.mp4"/>
+     <SegmentURL media="bipbop_audio1.m4s"/>
+     <SegmentURL media="bipbop_audio2.m4s"/>
+     <SegmentURL media="bipbop_audio3.m4s"/>
+     <SegmentURL media="bipbop_audio4.m4s"/>
+     <SegmentURL media="bipbop_audio5.m4s"/>
+     <SegmentURL media="bipbop_audio6.m4s"/>
+     <SegmentURL media="bipbop_audio7.m4s"/>
+     <SegmentURL media="bipbop_audio8.m4s"/>
+     <SegmentURL media="bipbop_audio9.m4s"/>
+     <SegmentURL media="bipbop_audio10.m4s"/>
+     <SegmentURL media="bipbop_audio11.m4s"/>
+    </SegmentList>
+   </Representation>
+  </AdaptationSet>
+ </Period>
+</MPD>
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.0-1.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.0-1.m4s
new file mode 100644
index 0000000000..2b95d49de9
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.0-1.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.0-1.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.0-1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.0-1.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.0-2.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.0-2.m4s
new file mode 100644
index 0000000000..3d95e7e2bf
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.0-2.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.0-2.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.0-2.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.0-2.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.0-init.mp4 b/dom/media/mediasource/test/bipbop/bipbop_offset_0.0-init.mp4
new file mode 100644
index 0000000000..cc7a48b5ce
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.0-init.mp4
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.0-init.mp4^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.0-init.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.0-init.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.1-1.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.1-1.m4s
new file mode 100644
index 0000000000..d67c4ef4cc
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.1-1.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.1-1.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.1-1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.1-1.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.1-2.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.1-2.m4s
new file mode 100644
index 0000000000..be155dbb9c
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.1-2.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.1-2.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.1-2.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.1-2.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.1-init.mp4 b/dom/media/mediasource/test/bipbop/bipbop_offset_0.1-init.mp4
new file mode 100644
index 0000000000..b67beb9548
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.1-init.mp4
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.1-init.mp4^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.1-init.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.1-init.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.2-1.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.2-1.m4s
new file mode 100644
index 0000000000..2056aaec7f
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.2-1.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.2-1.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.2-1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.2-1.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.2-2.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.2-2.m4s
new file mode 100644
index 0000000000..ccdad15c39
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.2-2.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.2-2.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.2-2.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.2-2.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.2-init.mp4 b/dom/media/mediasource/test/bipbop/bipbop_offset_0.2-init.mp4
new file mode 100644
index 0000000000..5b618c64d8
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.2-init.mp4
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.2-init.mp4^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.2-init.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.2-init.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.3-1.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.3-1.m4s
new file mode 100644
index 0000000000..c834ea6ae8
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.3-1.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.3-1.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.3-1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.3-1.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.3-2.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.3-2.m4s
new file mode 100644
index 0000000000..aad6b355ae
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.3-2.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.3-2.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.3-2.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.3-2.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.3-init.mp4 b/dom/media/mediasource/test/bipbop/bipbop_offset_0.3-init.mp4
new file mode 100644
index 0000000000..1f878bc84b
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.3-init.mp4
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.3-init.mp4^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.3-init.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.3-init.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.4-1.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.4-1.m4s
new file mode 100644
index 0000000000..88f05ee8bb
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.4-1.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.4-1.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.4-1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.4-1.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.4-2.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.4-2.m4s
new file mode 100644
index 0000000000..23ecab42e2
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.4-2.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.4-2.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.4-2.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.4-2.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.4-init.mp4 b/dom/media/mediasource/test/bipbop/bipbop_offset_0.4-init.mp4
new file mode 100644
index 0000000000..3e5ad8ad3b
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.4-init.mp4
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.4-init.mp4^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.4-init.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.4-init.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.5-1.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.5-1.m4s
new file mode 100644
index 0000000000..df05700d87
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.5-1.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.5-1.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.5-1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.5-1.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.5-2.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.5-2.m4s
new file mode 100644
index 0000000000..14daa425c7
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.5-2.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.5-2.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.5-2.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.5-2.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.5-init.mp4 b/dom/media/mediasource/test/bipbop/bipbop_offset_0.5-init.mp4
new file mode 100644
index 0000000000..2101dd876c
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.5-init.mp4
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.5-init.mp4^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.5-init.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.5-init.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.6-1.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.6-1.m4s
new file mode 100644
index 0000000000..ef0a4614fc
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.6-1.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.6-1.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.6-1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.6-1.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.6-2.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.6-2.m4s
new file mode 100644
index 0000000000..8f7c819867
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.6-2.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.6-2.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.6-2.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.6-2.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.6-init.mp4 b/dom/media/mediasource/test/bipbop/bipbop_offset_0.6-init.mp4
new file mode 100644
index 0000000000..91f48ab6a1
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.6-init.mp4
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.6-init.mp4^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.6-init.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.6-init.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.7-1.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.7-1.m4s
new file mode 100644
index 0000000000..dded8a37af
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.7-1.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.7-1.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.7-1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.7-1.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.7-2.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.7-2.m4s
new file mode 100644
index 0000000000..2a3c10859c
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.7-2.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.7-2.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.7-2.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.7-2.m4s^headers^
@@ -0,0 +1 @@
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diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.7-init.mp4 b/dom/media/mediasource/test/bipbop/bipbop_offset_0.7-init.mp4
new file mode 100644
index 0000000000..cf45610f7b
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.7-init.mp4
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.7-init.mp4^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.7-init.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.7-init.mp4^headers^
@@ -0,0 +1 @@
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diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.8-1.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.8-1.m4s
new file mode 100644
index 0000000000..74f0addd4f
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.8-1.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.8-1.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.8-1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.8-1.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.8-2.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.8-2.m4s
new file mode 100644
index 0000000000..f062c85333
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.8-2.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.8-2.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.8-2.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.8-2.m4s^headers^
@@ -0,0 +1 @@
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diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.8-init.mp4 b/dom/media/mediasource/test/bipbop/bipbop_offset_0.8-init.mp4
new file mode 100644
index 0000000000..30a0ab0fed
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.8-init.mp4
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.8-init.mp4^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.8-init.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.8-init.mp4^headers^
@@ -0,0 +1 @@
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diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.9-1.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.9-1.m4s
new file mode 100644
index 0000000000..b74ebf1f64
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.9-1.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.9-1.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.9-1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.9-1.m4s^headers^
@@ -0,0 +1 @@
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diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.9-2.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_0.9-2.m4s
new file mode 100644
index 0000000000..eabd8a3411
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.9-2.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.9-2.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.9-2.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.9-2.m4s^headers^
@@ -0,0 +1 @@
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diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.9-init.mp4 b/dom/media/mediasource/test/bipbop/bipbop_offset_0.9-init.mp4
new file mode 100644
index 0000000000..449722b0fd
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.9-init.mp4
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_0.9-init.mp4^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.9-init.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_0.9-init.mp4^headers^
@@ -0,0 +1 @@
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diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_1.0-1.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_1.0-1.m4s
new file mode 100644
index 0000000000..e032afcc4f
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_1.0-1.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_1.0-1.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_1.0-1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_1.0-1.m4s^headers^
@@ -0,0 +1 @@
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diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_1.0-2.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_1.0-2.m4s
new file mode 100644
index 0000000000..6542c8d3d3
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_1.0-2.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_1.0-2.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_1.0-2.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_1.0-2.m4s^headers^
@@ -0,0 +1 @@
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diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_1.0-init.mp4 b/dom/media/mediasource/test/bipbop/bipbop_offset_1.0-init.mp4
new file mode 100644
index 0000000000..0a9da048f0
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_1.0-init.mp4
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_1.0-init.mp4^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_1.0-init.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_1.0-init.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_1.1-1.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_1.1-1.m4s
new file mode 100644
index 0000000000..1b8b22be4a
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_1.1-1.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_1.1-1.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_1.1-1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_1.1-1.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_1.1-2.m4s b/dom/media/mediasource/test/bipbop/bipbop_offset_1.1-2.m4s
new file mode 100644
index 0000000000..3de855982f
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_1.1-2.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_1.1-2.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_1.1-2.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_1.1-2.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_1.1-init.mp4 b/dom/media/mediasource/test/bipbop/bipbop_offset_1.1-init.mp4
new file mode 100644
index 0000000000..80b3814f7c
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_1.1-init.mp4
diff --git a/dom/media/mediasource/test/bipbop/bipbop_offset_1.1-init.mp4^headers^ b/dom/media/mediasource/test/bipbop/bipbop_offset_1.1-init.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_offset_1.1-init.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_trailing_skip_box_video1.m4s b/dom/media/mediasource/test/bipbop/bipbop_trailing_skip_box_video1.m4s
new file mode 100644
index 0000000000..fa5d454277
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_trailing_skip_box_video1.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_trailing_skip_box_video1.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_trailing_skip_box_video1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_trailing_skip_box_video1.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video1.m4s b/dom/media/mediasource/test/bipbop/bipbop_video1.m4s
new file mode 100644
index 0000000000..9291182516
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video1.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video1.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_video1.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video1.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video10.m4s b/dom/media/mediasource/test/bipbop/bipbop_video10.m4s
new file mode 100644
index 0000000000..72c7afaca7
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video10.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video10.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_video10.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video10.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video11.m4s b/dom/media/mediasource/test/bipbop/bipbop_video11.m4s
new file mode 100644
index 0000000000..e6109f5e71
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video11.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video11.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_video11.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video11.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video12.m4s b/dom/media/mediasource/test/bipbop/bipbop_video12.m4s
new file mode 100644
index 0000000000..5c54a510f7
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video12.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video12.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_video12.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video12.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video13.m4s b/dom/media/mediasource/test/bipbop/bipbop_video13.m4s
new file mode 100644
index 0000000000..c64f38a337
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video13.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video13.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_video13.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video13.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video2.m4s b/dom/media/mediasource/test/bipbop/bipbop_video2.m4s
new file mode 100644
index 0000000000..cd34fae561
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video2.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video2.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_video2.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video2.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video3.m4s b/dom/media/mediasource/test/bipbop/bipbop_video3.m4s
new file mode 100644
index 0000000000..5a13340043
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video3.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video3.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_video3.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video3.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video4.m4s b/dom/media/mediasource/test/bipbop/bipbop_video4.m4s
new file mode 100644
index 0000000000..e8d96b6ed1
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video4.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video4.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_video4.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video4.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video5.m4s b/dom/media/mediasource/test/bipbop/bipbop_video5.m4s
new file mode 100644
index 0000000000..ca6a820468
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video5.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video5.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_video5.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video5.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video6.m4s b/dom/media/mediasource/test/bipbop/bipbop_video6.m4s
new file mode 100644
index 0000000000..fe9824355b
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video6.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video6.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_video6.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video6.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video7.m4s b/dom/media/mediasource/test/bipbop/bipbop_video7.m4s
new file mode 100644
index 0000000000..3351fa6859
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video7.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video7.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_video7.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video7.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video8.m4s b/dom/media/mediasource/test/bipbop/bipbop_video8.m4s
new file mode 100644
index 0000000000..af26ae5f9e
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video8.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video8.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_video8.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video8.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video9.m4s b/dom/media/mediasource/test/bipbop/bipbop_video9.m4s
new file mode 100644
index 0000000000..25be672c15
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video9.m4s
diff --git a/dom/media/mediasource/test/bipbop/bipbop_video9.m4s^headers^ b/dom/media/mediasource/test/bipbop/bipbop_video9.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_video9.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbop_videoinit.mp4 b/dom/media/mediasource/test/bipbop/bipbop_videoinit.mp4
new file mode 100644
index 0000000000..7c9c533c36
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_videoinit.mp4
diff --git a/dom/media/mediasource/test/bipbop/bipbop_videoinit.mp4^headers^ b/dom/media/mediasource/test/bipbop/bipbop_videoinit.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbop_videoinit.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bipbop/bipbopinit.mp4 b/dom/media/mediasource/test/bipbop/bipbopinit.mp4
new file mode 100644
index 0000000000..39f0575a71
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbopinit.mp4
diff --git a/dom/media/mediasource/test/bipbop/bipbopinit.mp4^headers^ b/dom/media/mediasource/test/bipbop/bipbopinit.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/bipbop/bipbopinit.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/bug1718709_high_res.mp4 b/dom/media/mediasource/test/bug1718709_high_res.mp4
new file mode 100644
index 0000000000..3f211d2370
--- /dev/null
+++ b/dom/media/mediasource/test/bug1718709_high_res.mp4
diff --git a/dom/media/mediasource/test/bug1718709_low_res.mp4 b/dom/media/mediasource/test/bug1718709_low_res.mp4
new file mode 100644
index 0000000000..dc5cd6b7f1
--- /dev/null
+++ b/dom/media/mediasource/test/bug1718709_low_res.mp4
diff --git a/dom/media/mediasource/test/crashtests/1005366.html b/dom/media/mediasource/test/crashtests/1005366.html
new file mode 100644
index 0000000000..aa8b7f652e
--- /dev/null
+++ b/dom/media/mediasource/test/crashtests/1005366.html
@@ -0,0 +1,27 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="UTF-8">
+<script>
+
+/*
+user_pref("media.mediasource.enabled", true);
+*/
+
+function boom()
+{
+    var source = new window.MediaSource();
+    var videoElement = document.createElementNS('http://www.w3.org/1999/xhtml', 'video');
+    videoElement.src = URL.createObjectURL(source);
+
+    setTimeout(function() {
+        var buf = source.addSourceBuffer("video/webm");
+        buf.abort();
+        buf.appendBuffer(new Float32Array(203));
+    }, 0);
+}
+
+</script>
+</head>
+<body onload="boom();"></body>
+</html>
diff --git a/dom/media/mediasource/test/crashtests/1059035.html b/dom/media/mediasource/test/crashtests/1059035.html
new file mode 100644
index 0000000000..9dfda34b82
--- /dev/null
+++ b/dom/media/mediasource/test/crashtests/1059035.html
@@ -0,0 +1,26 @@
+<!DOCTYPE html>
+<html>
+<head>
+<script>
+
+/*
+user_pref("media.mediasource.enabled", true);
+*/
+
+function boom()
+{
+    var mediaSource = new MediaSource();
+    var htmlAudio = document.createElement("audio");
+    htmlAudio.src = URL.createObjectURL(mediaSource);
+
+    setTimeout(function() {
+        var sourceBuffer = mediaSource.addSourceBuffer("video/webm");
+        mediaSource.removeSourceBuffer(sourceBuffer);
+        sourceBuffer.remove(0, 0);
+    }, 0);
+}
+
+</script>
+</head>
+<body onload="boom();"></body>
+</html>
diff --git a/dom/media/mediasource/test/crashtests/926665.html b/dom/media/mediasource/test/crashtests/926665.html
new file mode 100644
index 0000000000..ccac5a7644
--- /dev/null
+++ b/dom/media/mediasource/test/crashtests/926665.html
@@ -0,0 +1,26 @@
+<html>

+<head>

+<meta charset="UTF-8">

+<script style="display: none;" id="fuzz1" type="text/javascript">

+

+function boom()

+{

+    var mediaSource = new window.MediaSource();

+    var mediaSourceURL = URL.createObjectURL(mediaSource);

+    var v1 = document.createElement('video');

+    v1.src = mediaSourceURL;

+    mediaSource.addEventListener("sourceopen", function (e) {

+        var v2 = document.createElement('video');

+        v2.src = mediaSourceURL;

+        setTimeout(function () {

+            v2.src = "data:text/plain,1";

+            v1.src = "data:text/plain,2";

+        }, 0);

+    });

+}

+

+</script>

+</head>

+

+<body onload="boom();"></body>

+</html>

diff --git a/dom/media/mediasource/test/crashtests/931388.html b/dom/media/mediasource/test/crashtests/931388.html
new file mode 100644
index 0000000000..cdb5bd9add
--- /dev/null
+++ b/dom/media/mediasource/test/crashtests/931388.html
@@ -0,0 +1,17 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="UTF-8">
+<script>
+
+function boom()
+{
+  var v = document.createElement('video');
+  v.src = URL.createObjectURL(new MediaSource());
+  v.play();
+}
+
+</script>
+</head>
+<body onload="boom();"></body>
+</html>
diff --git a/dom/media/mediasource/test/crashtests/crashtests.list b/dom/media/mediasource/test/crashtests/crashtests.list
new file mode 100644
index 0000000000..e16ec261d2
--- /dev/null
+++ b/dom/media/mediasource/test/crashtests/crashtests.list
@@ -0,0 +1,4 @@
+test-pref(media.mediasource.enabled,true) load 926665.html
+test-pref(media.mediasource.enabled,true) load 931388.html
+test-pref(media.mediasource.enabled,true) load 1005366.html
+test-pref(media.mediasource.enabled,true) load 1059035.html
diff --git a/dom/media/mediasource/test/flac/00001.m4s b/dom/media/mediasource/test/flac/00001.m4s
new file mode 100644
index 0000000000..02745ba2f8
--- /dev/null
+++ b/dom/media/mediasource/test/flac/00001.m4s
diff --git a/dom/media/mediasource/test/flac/00001.m4s^headers^ b/dom/media/mediasource/test/flac/00001.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/flac/00001.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/flac/00002.m4s b/dom/media/mediasource/test/flac/00002.m4s
new file mode 100644
index 0000000000..cd6b1f5949
--- /dev/null
+++ b/dom/media/mediasource/test/flac/00002.m4s
diff --git a/dom/media/mediasource/test/flac/00002.m4s^headers^ b/dom/media/mediasource/test/flac/00002.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/flac/00002.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/flac/00003.m4s b/dom/media/mediasource/test/flac/00003.m4s
new file mode 100644
index 0000000000..c5b78e1ce0
--- /dev/null
+++ b/dom/media/mediasource/test/flac/00003.m4s
diff --git a/dom/media/mediasource/test/flac/00003.m4s^headers^ b/dom/media/mediasource/test/flac/00003.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/flac/00003.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/flac/IS.mp4 b/dom/media/mediasource/test/flac/IS.mp4
new file mode 100644
index 0000000000..7f108602fd
--- /dev/null
+++ b/dom/media/mediasource/test/flac/IS.mp4
diff --git a/dom/media/mediasource/test/flac/IS.mp4^headers^ b/dom/media/mediasource/test/flac/IS.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/flac/IS.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/init-trackid2.mp4 b/dom/media/mediasource/test/init-trackid2.mp4
new file mode 100644
index 0000000000..c96da9d4df
--- /dev/null
+++ b/dom/media/mediasource/test/init-trackid2.mp4
diff --git a/dom/media/mediasource/test/init-trackid2.mp4^headers^ b/dom/media/mediasource/test/init-trackid2.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/init-trackid2.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/init-trackid3.mp4 b/dom/media/mediasource/test/init-trackid3.mp4
new file mode 100644
index 0000000000..e37d8ea098
--- /dev/null
+++ b/dom/media/mediasource/test/init-trackid3.mp4
diff --git a/dom/media/mediasource/test/init-trackid3.mp4^headers^ b/dom/media/mediasource/test/init-trackid3.mp4^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/init-trackid3.mp4^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/mediasource.js b/dom/media/mediasource/test/mediasource.js
new file mode 100644
index 0000000000..440b05009f
--- /dev/null
+++ b/dom/media/mediasource/test/mediasource.js
@@ -0,0 +1,233 @@
+// Helpers for Media Source Extensions tests
+
+let gMSETestPrefs = [
+  ["media.mediasource.enabled", true],
+  ["media.audio-max-decode-error", 0],
+  ["media.video-max-decode-error", 0],
+];
+
+// Called before runWithMSE() to set the prefs before running MSE tests.
+function addMSEPrefs(...prefs) {
+  gMSETestPrefs = gMSETestPrefs.concat(prefs);
+}
+
+async function runWithMSE(testFunction) {
+  await once(window, "load");
+  await SpecialPowers.pushPrefEnv({ set: gMSETestPrefs });
+
+  const ms = new MediaSource();
+
+  const el = document.createElement("video");
+  el.src = URL.createObjectURL(ms);
+  el.preload = "auto";
+
+  document.body.appendChild(el);
+  SimpleTest.registerCleanupFunction(() => {
+    el.remove();
+    el.removeAttribute("src");
+    el.load();
+  });
+  try {
+    await testFunction(ms, el);
+  } catch (e) {
+    ok(false, `${testFunction.name} failed with error ${e.name}`);
+    throw e;
+  }
+}
+
+async function fetchWithXHR(uri) {
+  return new Promise(resolve => {
+    const xhr = new XMLHttpRequest();
+    xhr.open("GET", uri, true);
+    xhr.responseType = "arraybuffer";
+    xhr.addEventListener("load", function() {
+      is(
+        xhr.status,
+        200,
+        "fetchWithXHR load uri='" + uri + "' status=" + xhr.status
+      );
+      resolve(xhr.response);
+    });
+    xhr.send();
+  });
+}
+
+function range(start, end) {
+  const rv = [];
+  for (let i = start; i < end; ++i) {
+    rv.push(i);
+  }
+  return rv;
+}
+
+function must_throw(f, msg, error = true) {
+  try {
+    f();
+    ok(!error, msg);
+  } catch (e) {
+    ok(error, msg);
+    if (error === true) {
+      ok(
+        false,
+        `Please provide name of expected error! Got ${e.name}: ${e.message}.`
+      );
+    } else if (e.name != error) {
+      throw e;
+    }
+  }
+}
+
+async function must_reject(f, msg, error = true) {
+  try {
+    await f();
+    ok(!error, msg);
+  } catch (e) {
+    ok(error, msg);
+    if (error === true) {
+      ok(
+        false,
+        `Please provide name of expected error! Got ${e.name}: ${e.message}.`
+      );
+    } else if (e.name != error) {
+      throw e;
+    }
+  }
+}
+
+const wait = ms => new Promise(resolve => setTimeout(resolve, ms));
+
+const must_not_throw = (f, msg) => must_throw(f, msg, false);
+const must_not_reject = (f, msg) => must_reject(f, msg, false);
+
+async function once(target, name) {
+  return new Promise(r => target.addEventListener(name, r, { once: true }));
+}
+
+function timeRangeToString(r) {
+  let str = "TimeRanges: ";
+  for (let i = 0; i < r.length; i++) {
+    str += "[" + r.start(i) + ", " + r.end(i) + ")";
+  }
+  return str;
+}
+
+async function loadSegment(sb, typedArrayOrArrayBuffer) {
+  const typedArray =
+    typedArrayOrArrayBuffer instanceof ArrayBuffer
+      ? new Uint8Array(typedArrayOrArrayBuffer)
+      : typedArrayOrArrayBuffer;
+  info(
+    `Loading buffer: [${typedArray.byteOffset}, ${typedArray.byteOffset +
+      typedArray.byteLength})`
+  );
+  const beforeBuffered = timeRangeToString(sb.buffered);
+  const p = once(sb, "update");
+  sb.appendBuffer(typedArray);
+  await p;
+  const afterBuffered = timeRangeToString(sb.buffered);
+  info(
+    `SourceBuffer buffered ranges grew from ${beforeBuffered} to ${afterBuffered}`
+  );
+}
+
+async function fetchAndLoad(sb, prefix, chunks, suffix) {
+  // Fetch the buffers in parallel.
+  const buffers = await Promise.all(
+    chunks.map(c => fetchWithXHR(prefix + c + suffix))
+  );
+
+  // Load them in series, as required per spec.
+  for (const buffer of buffers) {
+    await loadSegment(sb, buffer);
+  }
+}
+
+function loadSegmentAsync(sb, typedArrayOrArrayBuffer) {
+  const typedArray =
+    typedArrayOrArrayBuffer instanceof ArrayBuffer
+      ? new Uint8Array(typedArrayOrArrayBuffer)
+      : typedArrayOrArrayBuffer;
+  info(
+    `Loading buffer2: [${typedArray.byteOffset}, ${typedArray.byteOffset +
+      typedArray.byteLength})`
+  );
+  const beforeBuffered = timeRangeToString(sb.buffered);
+  return sb.appendBufferAsync(typedArray).then(() => {
+    const afterBuffered = timeRangeToString(sb.buffered);
+    info(
+      `SourceBuffer buffered ranges grew from ${beforeBuffered} to ${afterBuffered}`
+    );
+  });
+}
+
+function fetchAndLoadAsync(sb, prefix, chunks, suffix) {
+  // Fetch the buffers in parallel.
+  const buffers = {};
+  const fetches = [];
+  for (const chunk of chunks) {
+    fetches.push(
+      fetchWithXHR(prefix + chunk + suffix).then(
+        ((c, x) => (buffers[c] = x)).bind(null, chunk)
+      )
+    );
+  }
+
+  // Load them in series, as required per spec.
+  return Promise.all(fetches).then(function() {
+    let rv = Promise.resolve();
+    for (const chunk of chunks) {
+      rv = rv.then(loadSegmentAsync.bind(null, sb, buffers[chunk]));
+    }
+    return rv;
+  });
+}
+
+// Register timeout function to dump debugging logs.
+SimpleTest.registerTimeoutFunction(async function() {
+  for (const v of document.getElementsByTagName("video")) {
+    console.log(await SpecialPowers.wrap(v).mozRequestDebugInfo());
+  }
+  for (const a of document.getElementsByTagName("audio")) {
+    console.log(await SpecialPowers.wrap(a).mozRequestDebugInfo());
+  }
+});
+
+async function waitUntilTime(target, targetTime) {
+  await new Promise(resolve => {
+    target.addEventListener("waiting", function onwaiting() {
+      info("Got a waiting event at " + target.currentTime);
+      if (target.currentTime >= targetTime) {
+        target.removeEventListener("waiting", onwaiting);
+        resolve();
+      }
+    });
+  });
+  ok(true, "Reached target time of: " + targetTime);
+}
+
+// Log events for debugging.
+
+function logEvents(el) {
+  [
+    "suspend",
+    "play",
+    "canplay",
+    "canplaythrough",
+    "loadstart",
+    "loadedmetadata",
+    "loadeddata",
+    "playing",
+    "ended",
+    "error",
+    "stalled",
+    "emptied",
+    "abort",
+    "waiting",
+    "pause",
+    "durationchange",
+    "seeking",
+    "seeked",
+  ].forEach(type =>
+    el.addEventListener(type, e => info(`got ${e.type} event`))
+  );
+}
diff --git a/dom/media/mediasource/test/mochitest.ini b/dom/media/mediasource/test/mochitest.ini
new file mode 100644
index 0000000000..7e5c504559
--- /dev/null
+++ b/dom/media/mediasource/test/mochitest.ini
@@ -0,0 +1,211 @@
+[DEFAULT]
+subsuite = media
+support-files =
+  mediasource.js
+  seek.webm seek.webm^headers^
+  seek_lowres.webm seek_lowres.webm^headers^
+  bipbop/bipbop_300-3s.webm bipbop/bipbop_300-3s.webm^headers^
+  bipbop/bipbop2s.mp4 bipbop/bipbop2s.mp4^headers^
+  bipbop/bipbop_trailing_skip_box_video1.m4s
+  bipbop/bipbop_trailing_skip_box_video1.m4s^headers^
+  bipbop/bipbopinit.mp4 bipbop/bipbop_audioinit.mp4 bipbop/bipbop_videoinit.mp4
+  bipbop/bipbop1.m4s bipbop/bipbop_audio1.m4s bipbop/bipbop_video1.m4s
+  bipbop/bipbop2.m4s bipbop/bipbop_audio2.m4s bipbop/bipbop_video2.m4s
+  bipbop/bipbop3.m4s bipbop/bipbop_audio3.m4s bipbop/bipbop_video3.m4s
+  bipbop/bipbop4.m4s bipbop/bipbop_audio4.m4s bipbop/bipbop_video4.m4s
+  bipbop/bipbop5.m4s bipbop/bipbop_audio5.m4s bipbop/bipbop_video5.m4s
+  bipbop/bipbop6.m4s bipbop/bipbop_audio6.m4s bipbop/bipbop_video6.m4s
+  bipbop/bipbop7.m4s bipbop/bipbop_audio7.m4s bipbop/bipbop_video7.m4s
+  bipbop/bipbop8.m4s bipbop/bipbop_audio8.m4s bipbop/bipbop_video8.m4s
+  bipbop/bipbop9.m4s bipbop/bipbop_audio9.m4s bipbop/bipbop_video9.m4s
+  bipbop/bipbop10.m4s bipbop/bipbop_audio10.m4s bipbop/bipbop_video10.m4s
+  bipbop/bipbop11.m4s bipbop/bipbop_audio11.m4s bipbop/bipbop_video11.m4s
+  bipbop/bipbop12.m4s bipbop/bipbop_video12.m4s
+  bipbop/bipbop13.m4s bipbop/bipbop_video13.m4s
+  bipbop/bipbopinit.mp4^headers^ bipbop/bipbop_audioinit.mp4^headers^ bipbop/bipbop_videoinit.mp4^headers^
+  bipbop/bipbop1.m4s^headers^ bipbop/bipbop_audio1.m4s^headers^ bipbop/bipbop_video1.m4s^headers^
+  bipbop/bipbop2.m4s^headers^ bipbop/bipbop_audio2.m4s^headers^ bipbop/bipbop_video2.m4s^headers^
+  bipbop/bipbop3.m4s^headers^ bipbop/bipbop_audio3.m4s^headers^ bipbop/bipbop_video3.m4s^headers^
+  bipbop/bipbop4.m4s^headers^ bipbop/bipbop_audio4.m4s^headers^ bipbop/bipbop_video4.m4s^headers^
+  bipbop/bipbop5.m4s^headers^ bipbop/bipbop_audio5.m4s^headers^ bipbop/bipbop_video5.m4s^headers^
+  bipbop/bipbop6.m4s^headers^ bipbop/bipbop_audio6.m4s^headers^ bipbop/bipbop_video6.m4s^headers^
+  bipbop/bipbop7.m4s^headers^ bipbop/bipbop_audio7.m4s^headers^ bipbop/bipbop_video7.m4s^headers^
+  bipbop/bipbop8.m4s^headers^ bipbop/bipbop_audio8.m4s^headers^ bipbop/bipbop_video8.m4s^headers^
+  bipbop/bipbop9.m4s^headers^ bipbop/bipbop_audio9.m4s^headers^ bipbop/bipbop_video9.m4s^headers^
+  bipbop/bipbop10.m4s^headers^ bipbop/bipbop_audio10.m4s^headers^ bipbop/bipbop_video10.m4s^headers^
+  bipbop/bipbop11.m4s^headers^ bipbop/bipbop_audio11.m4s^headers^ bipbop/bipbop_video11.m4s^headers^
+  bipbop/bipbop12.m4s^headers^ bipbop/bipbop_video12.m4s^headers^
+  bipbop/bipbop13.m4s^headers^ bipbop/bipbop_video13.m4s^headers^
+  bipbop/bipbop_offset_0.0-1.m4s
+  bipbop/bipbop_offset_0.0-1.m4s^headers^
+  bipbop/bipbop_offset_0.0-2.m4s
+  bipbop/bipbop_offset_0.0-2.m4s^headers^
+  bipbop/bipbop_offset_0.0-init.mp4
+  bipbop/bipbop_offset_0.0-init.mp4^headers^
+  bipbop/bipbop_offset_0.1-1.m4s
+  bipbop/bipbop_offset_0.1-1.m4s^headers^
+  bipbop/bipbop_offset_0.1-2.m4s
+  bipbop/bipbop_offset_0.1-2.m4s^headers^
+  bipbop/bipbop_offset_0.1-init.mp4
+  bipbop/bipbop_offset_0.1-init.mp4^headers^
+  bipbop/bipbop_offset_0.2-1.m4s
+  bipbop/bipbop_offset_0.2-1.m4s^headers^
+  bipbop/bipbop_offset_0.2-2.m4s
+  bipbop/bipbop_offset_0.2-2.m4s^headers^
+  bipbop/bipbop_offset_0.2-init.mp4
+  bipbop/bipbop_offset_0.2-init.mp4^headers^
+  bipbop/bipbop_offset_0.3-1.m4s
+  bipbop/bipbop_offset_0.3-1.m4s^headers^
+  bipbop/bipbop_offset_0.3-2.m4s
+  bipbop/bipbop_offset_0.3-2.m4s^headers^
+  bipbop/bipbop_offset_0.3-init.mp4
+  bipbop/bipbop_offset_0.3-init.mp4^headers^
+  bipbop/bipbop_offset_0.4-1.m4s
+  bipbop/bipbop_offset_0.4-1.m4s^headers^
+  bipbop/bipbop_offset_0.4-2.m4s
+  bipbop/bipbop_offset_0.4-2.m4s^headers^
+  bipbop/bipbop_offset_0.4-init.mp4
+  bipbop/bipbop_offset_0.4-init.mp4^headers^
+  bipbop/bipbop_offset_0.5-1.m4s
+  bipbop/bipbop_offset_0.5-1.m4s^headers^
+  bipbop/bipbop_offset_0.5-2.m4s
+  bipbop/bipbop_offset_0.5-2.m4s^headers^
+  bipbop/bipbop_offset_0.5-init.mp4
+  bipbop/bipbop_offset_0.5-init.mp4^headers^
+  bipbop/bipbop_offset_0.6-1.m4s
+  bipbop/bipbop_offset_0.6-1.m4s^headers^
+  bipbop/bipbop_offset_0.6-2.m4s
+  bipbop/bipbop_offset_0.6-2.m4s^headers^
+  bipbop/bipbop_offset_0.6-init.mp4
+  bipbop/bipbop_offset_0.6-init.mp4^headers^
+  bipbop/bipbop_offset_0.7-1.m4s
+  bipbop/bipbop_offset_0.7-1.m4s^headers^
+  bipbop/bipbop_offset_0.7-2.m4s
+  bipbop/bipbop_offset_0.7-2.m4s^headers^
+  bipbop/bipbop_offset_0.7-init.mp4
+  bipbop/bipbop_offset_0.7-init.mp4^headers^
+  bipbop/bipbop_offset_0.8-1.m4s
+  bipbop/bipbop_offset_0.8-1.m4s^headers^
+  bipbop/bipbop_offset_0.8-2.m4s
+  bipbop/bipbop_offset_0.8-2.m4s^headers^
+  bipbop/bipbop_offset_0.8-init.mp4
+  bipbop/bipbop_offset_0.8-init.mp4^headers^
+  bipbop/bipbop_offset_0.9-1.m4s
+  bipbop/bipbop_offset_0.9-1.m4s^headers^
+  bipbop/bipbop_offset_0.9-2.m4s
+  bipbop/bipbop_offset_0.9-2.m4s^headers^
+  bipbop/bipbop_offset_0.9-init.mp4
+  bipbop/bipbop_offset_0.9-init.mp4^headers^
+  bipbop/bipbop_offset_1.0-1.m4s
+  bipbop/bipbop_offset_1.0-1.m4s^headers^
+  bipbop/bipbop_offset_1.0-2.m4s
+  bipbop/bipbop_offset_1.0-2.m4s^headers^
+  bipbop/bipbop_offset_1.0-init.mp4
+  bipbop/bipbop_offset_1.0-init.mp4^headers^
+  bipbop/bipbop_offset_1.1-1.m4s
+  bipbop/bipbop_offset_1.1-1.m4s^headers^
+  bipbop/bipbop_offset_1.1-2.m4s
+  bipbop/bipbop_offset_1.1-2.m4s^headers^
+  bipbop/bipbop_offset_1.1-init.mp4
+  bipbop/bipbop_offset_1.1-init.mp4^headers^
+  aac20-48000-64000-init.mp4   aac20-48000-64000-init.mp4^headers^
+  aac20-48000-64000-1.m4s aac20-48000-64000-1.m4s^headers^
+  aac20-48000-64000-2.m4s aac20-48000-64000-2.m4s^headers^
+  aac51-48000-128000-init.mp4 aac51-48000-128000-init.mp4^headers^
+  aac51-48000-128000-1.m4s aac51-48000-128000-1.m4s^headers^
+  aac51-48000-128000-2.m4s aac51-48000-128000-2.m4s^headers^
+  bipbop/bipbop_480_624kbps-videoinit.mp4 bipbop/bipbop_480_624kbps-videoinit.mp4^headers^
+  bipbop/bipbop_480_624kbps-video1.m4s bipbop/bipbop_480_624kbps-video1.m4s^headers^
+  bipbop/bipbop_480_624kbps-video2.m4s bipbop/bipbop_480_624kbps-video2.m4s^headers^
+  flac/IS.mp4 flac/IS.mp4^headers^ flac/00001.m4s flac/00001.m4s^headers^
+  flac/00002.m4s flac/00002.m4s^headers^ flac/00003.m4s flac/00003.m4s^headers^
+  avc3/init.mp4 avc3/init.mp4^headers^ avc3/segment1.m4s avc3/segment1.m4s^headers^
+  tags_before_cluster.webm
+  tags_before_cluster.webm^header^
+  1516754.webm 1516754.webm^headers^
+  init-trackid2.mp4 init-trackid3.mp4 segment-2.0001.m4s segment-2.0002.m4s segment-3.0001.m4s segment-3.0002.m4s
+  init-trackid2.mp4^headers^ init-trackid3.mp4^headers^ segment-2.0001.m4s^headers^ segment-2.0002.m4s^headers^
+  segment-3.0001.m4s^headers^ segment-3.0002.m4s^headers^
+  wmf_mismatchedaudiotime.mp4
+  bug1718709_low_res.mp4
+  bug1718709_high_res.mp4
+  whitenoise-he-aac-5s.mp4
+
+[test_AbortAfterPartialMediaSegment.html]
+[test_AppendPartialInitSegment.html]
+[test_AVC3_mp4.html]
+[test_AudioChange_mp4.html]
+[test_AudioChange_mp4_WebAudio.html]
+[test_AutoRevocation.html]
+tags = firstpartyisolation
+[test_BufferedSeek.html]
+[test_BufferedSeek_mp4.html]
+[test_BufferingWait.html]
+[test_BufferingWait_mp4.html]
+[test_ChangeType.html]
+[test_ChangeWhileWaitingOnMissingData_mp4.html]
+[test_DifferentStreamStartTimes.html]
+[test_DrainOnMissingData_mp4.html]
+[test_DurationChange.html]
+[test_DurationUpdated.html]
+[test_DurationUpdated_mp4.html]
+[test_EndedEvent.html]
+[test_EndOfStream.html]
+[test_EndOfStream_mp4.html]
+[test_Eviction_mp4.html]
+[test_ExperimentalAsync.html]
+[test_FrameSelection.html]
+skip-if = toolkit == 'android' # bug 1341519, bug 1401090
+[test_FrameSelection_mp4.html]
+skip-if = os == 'win' # bug 1487973,
+    (os == 'mac') # mac due to bug 1487973
+[test_HaveMetadataUnbufferedSeek.html]
+[test_HaveMetadataUnbufferedSeek_mp4.html]
+[test_HEAAC_extradata.html]
+[test_InputBufferIsCleared.html]
+[test_LiveSeekable.html]
+[test_LoadedDataFired_mp4.html]
+[test_LoadedMetadataFired.html]
+[test_LoadedMetadataFired_mp4.html]
+[test_MediaSource.html]
+[test_MediaSource_capture_gc.html]
+[test_MediaSource_memory_reporting.html]
+[test_MediaSource_mp4.html]
+[test_MediaSource_flac_mp4.html]
+[test_MediaSource_disabled.html]
+[test_MultipleInitSegments.html]
+[test_MultipleInitSegments_mp4.html]
+[test_OnEvents.html]
+[test_PlayEvents.html]
+[test_PlayEventsAutoPlaying.html]
+[test_PlayEventsAutoPlaying2.html]
+[test_RemoveSourceBuffer.html]
+[test_Resolution_change_should_not_cause_video_freeze.html]
+[test_ResumeAfterClearing_mp4.html]
+[test_SeekableBeforeAndAfterEndOfStream.html]
+[test_SeekableBeforeAndAfterEndOfStream_mp4.html]
+[test_SeekableBeforeAndAfterEndOfStreamSplit.html]
+[test_SeekableBeforeAndAfterEndOfStreamSplit_mp4.html]
+[test_SeekNoData_mp4.html]
+[test_SeekedEvent_mp4.html]
+[test_SeekToEnd_mp4.html]
+[test_SeekToLastFrame_mp4.html]
+[test_SeekTwice_mp4.html]
+[test_Sequence_mp4.html]
+[test_SetModeThrows.html]
+[test_SplitAppendDelay.html]
+[test_SplitAppendDelay_mp4.html]
+[test_SplitAppend.html]
+[test_SplitAppend_mp4.html]
+[test_Threshold_mp4.html]
+[test_TimestampOffset_mp4.html]
+[test_trackidchange_mp4.html]
+[test_TruncatedDuration.html]
+[test_TruncatedDuration_mp4.html]
+[test_WaitingOnMissingData.html]
+[test_WaitingOnMissingData_mp4.html]
+[test_WaitingOnMissingDataEnded_mp4.html]
+[test_WaitingToEndedTransition_mp4.html]
+skip-if = (os == 'linux') # Bug 1495167
+[test_WebMTagsBeforeCluster.html]
+[test_WMFUnmatchedAudioDataTime.html]
diff --git a/dom/media/mediasource/test/seek.webm b/dom/media/mediasource/test/seek.webm
new file mode 100644
index 0000000000..72b0297233
--- /dev/null
+++ b/dom/media/mediasource/test/seek.webm
diff --git a/dom/media/mediasource/test/seek.webm^headers^ b/dom/media/mediasource/test/seek.webm^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/seek.webm^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/seek_lowres.webm b/dom/media/mediasource/test/seek_lowres.webm
new file mode 100644
index 0000000000..8a76e06470
--- /dev/null
+++ b/dom/media/mediasource/test/seek_lowres.webm
diff --git a/dom/media/mediasource/test/seek_lowres.webm^headers^ b/dom/media/mediasource/test/seek_lowres.webm^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/seek_lowres.webm^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/segment-2.0001.m4s b/dom/media/mediasource/test/segment-2.0001.m4s
new file mode 100644
index 0000000000..b63fd6aaa6
--- /dev/null
+++ b/dom/media/mediasource/test/segment-2.0001.m4s
diff --git a/dom/media/mediasource/test/segment-2.0001.m4s^headers^ b/dom/media/mediasource/test/segment-2.0001.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/segment-2.0001.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/segment-2.0002.m4s b/dom/media/mediasource/test/segment-2.0002.m4s
new file mode 100644
index 0000000000..3a0051f10e
--- /dev/null
+++ b/dom/media/mediasource/test/segment-2.0002.m4s
diff --git a/dom/media/mediasource/test/segment-2.0002.m4s^headers^ b/dom/media/mediasource/test/segment-2.0002.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/segment-2.0002.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/segment-3.0001.m4s b/dom/media/mediasource/test/segment-3.0001.m4s
new file mode 100644
index 0000000000..71e33f0e8f
--- /dev/null
+++ b/dom/media/mediasource/test/segment-3.0001.m4s
diff --git a/dom/media/mediasource/test/segment-3.0001.m4s^headers^ b/dom/media/mediasource/test/segment-3.0001.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/segment-3.0001.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/segment-3.0002.m4s b/dom/media/mediasource/test/segment-3.0002.m4s
new file mode 100644
index 0000000000..10a3ce695d
--- /dev/null
+++ b/dom/media/mediasource/test/segment-3.0002.m4s
diff --git a/dom/media/mediasource/test/segment-3.0002.m4s^headers^ b/dom/media/mediasource/test/segment-3.0002.m4s^headers^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/segment-3.0002.m4s^headers^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/tags_before_cluster.webm b/dom/media/mediasource/test/tags_before_cluster.webm
new file mode 100644
index 0000000000..cf7d596b0e
--- /dev/null
+++ b/dom/media/mediasource/test/tags_before_cluster.webm
diff --git a/dom/media/mediasource/test/tags_before_cluster.webm^header^ b/dom/media/mediasource/test/tags_before_cluster.webm^header^
new file mode 100644
index 0000000000..4030ea1d3d
--- /dev/null
+++ b/dom/media/mediasource/test/tags_before_cluster.webm^header^
@@ -0,0 +1 @@
+Cache-Control: no-store
diff --git a/dom/media/mediasource/test/test_AVC3_mp4.html b/dom/media/mediasource/test/test_AVC3_mp4.html
new file mode 100644
index 0000000000..dd20feed06
--- /dev/null
+++ b/dom/media/mediasource/test/test_AVC3_mp4.html
@@ -0,0 +1,38 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: AVC3 content playback.</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, el) => {
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  const videosb = ms.addSourceBuffer("video/mp4");
+
+  await fetchAndLoad(videosb, "avc3/init", [""], ".mp4");
+  const p = once(el, "loadeddata");
+  await fetchAndLoad(videosb, "avc3/segment", range(1, 2), ".m4s");
+  await p;
+  is(videosb.buffered.length, 1, "continuous buffered range");
+  ok(true, "got loadeddata");
+  ms.endOfStream();
+  await once(ms, "sourceended");
+  ok(true, "endOfStream completed");
+  // Now ensure that we can play to the end.
+  el.play();
+  await once(el, "ended");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_AbortAfterPartialMediaSegment.html b/dom/media/mediasource/test/test_AbortAfterPartialMediaSegment.html
new file mode 100644
index 0000000000..4c695f48c7
--- /dev/null
+++ b/dom/media/mediasource/test/test_AbortAfterPartialMediaSegment.html
@@ -0,0 +1,62 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: can properly resume after a partial media segment header followed by abort </title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+const VIDEO_CODEC_STRING = 'video/webm; codecs="vp09.00.51.08.01.01.01.01"';
+
+const logError = (error) => {
+  console.error(error, error.message);
+  ok(false, "should not reach here");
+};
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+
+  const supported = MediaSource.isTypeSupported(VIDEO_CODEC_STRING);
+  if (!supported) {
+    ok(true, "vp9 isn't supported on this platform, abort");
+    SimpleTest.finish();
+    return;
+  }
+  const sb = ms.addSourceBuffer(VIDEO_CODEC_STRING);
+
+  const arrayBuffer = await fetchWithXHR("1516754.webm");
+  info("- append init segment, a media segment and a partial media segment header -");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 0, 87355 + 3000));
+
+  info("- wait for updateend -");
+  await once(sb, "updateend");
+
+  // start seeking.
+  v.currentTime = 11;
+  v.addEventListener("seeked", () => {
+    info("- seek completed -");
+    SimpleTest.finish();
+  });
+
+  sb.abort();
+
+  info("- append init segment -");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 0, 3150));
+  info("- wait for updateend -");
+  await once(sb, "updateend");
+  info("- append media segment 10-15s -");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 159968, 72931));
+
+  // We now wait for seek to complete
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_AppendPartialInitSegment.html b/dom/media/mediasource/test/test_AppendPartialInitSegment.html
new file mode 100644
index 0000000000..408c073bd6
--- /dev/null
+++ b/dom/media/mediasource/test/test_AppendPartialInitSegment.html
@@ -0,0 +1,43 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: split init segment and append them separately </title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+
+  const arrayBuffer = await fetchWithXHR("seek.webm");
+  // init segment is total 236 bytes.
+  info("- append partial init segment -");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 0, 100));
+
+  info("- wait for updateend -");
+  await once(sb, "updateend");
+
+  info("- append remaining init segment -");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 100, 136));
+
+  info("- wait for metadata -");
+  await once(v, "loadedmetadata");
+  is(v.videoWidth, 320, "videoWidth has correct initial value");
+  is(v.videoHeight, 240, "videoHeight has correct initial value");
+
+  info("- wait for updateend -");
+  await once(sb, "updateend");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_AudioChange_mp4.html b/dom/media/mediasource/test/test_AudioChange_mp4.html
new file mode 100644
index 0000000000..9051af05a1
--- /dev/null
+++ b/dom/media/mediasource/test/test_AudioChange_mp4.html
@@ -0,0 +1,49 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: basic functionality</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+// This test checks loading a stereo segment, followed by a 5.1 segment plays without error.
+
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  logEvents(el);
+
+  const audiosb = ms.addSourceBuffer("audio/mp4");
+  el.addEventListener("error", e => {
+    ok(false, `should not fire ${e.type} event`);
+    SimpleTest.finish();
+  });
+  is(el.readyState, el.HAVE_NOTHING, "readyState is HAVE_NOTHING");
+  let p = once(el, "loadedmetadata");
+  await fetchAndLoad(audiosb, "aac20-48000-64000-", ["init"], ".mp4");
+  await p;
+  ok(true, "got loadedmetadata event");
+  p = Promise.all([once(el, "loadeddata"), once(el, "canplay")]);
+  await fetchAndLoad(audiosb, "aac20-48000-64000-", ["1"], ".m4s");
+  await p;
+  ok(true, "got canplay event");
+  el.play();
+  await fetchAndLoad(audiosb, "aac51-48000-128000-", ["init"], ".mp4");
+  await fetchAndLoad(audiosb, "aac51-48000-128000-", ["2"], ".m4s");
+  ms.endOfStream();
+  await once(el, "ended");
+  ok(el.currentTime >= 6, "played to the end");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_AudioChange_mp4_WebAudio.html b/dom/media/mediasource/test/test_AudioChange_mp4_WebAudio.html
new file mode 100644
index 0000000000..c76342f793
--- /dev/null
+++ b/dom/media/mediasource/test/test_AudioChange_mp4_WebAudio.html
@@ -0,0 +1,55 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: basic functionality</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+// This test checks loading a stereo segment, followed by a 5.1 segment plays
+// without error, when the audio is being routed to an AudioContext.
+
+const ac = new AudioContext();
+
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  const source = ac.createMediaElementSource(el);
+  source.connect(ac.destination);
+
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  logEvents(el);
+
+  const audiosb = ms.addSourceBuffer("audio/mp4");
+  el.addEventListener("error", e => {
+    ok(false, `should not fire ${e.type} event`);
+    SimpleTest.finish();
+  });
+  is(el.readyState, el.HAVE_NOTHING, "readyState is HAVE_NOTHING");
+  let p = once(el, "loadedmetadata");
+  await fetchAndLoad(audiosb, "aac20-48000-64000-", ["init"], ".mp4");
+  await p;
+  ok(true, "got loadedmetadata event");
+  p = Promise.all([once(el, "loadeddata"), once(el, "canplay")]);
+  await fetchAndLoad(audiosb, "aac20-48000-64000-", ["1"], ".m4s");
+  await p;
+  ok(true, "got canplay event");
+  el.play();
+  await fetchAndLoad(audiosb, "aac51-48000-128000-", ["init"], ".mp4");
+  await fetchAndLoad(audiosb, "aac51-48000-128000-", ["2"], ".m4s");
+  ms.endOfStream();
+  await once(el, "ended");
+  ok(el.currentTime >= 6, "played to the end");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_AutoRevocation.html b/dom/media/mediasource/test/test_AutoRevocation.html
new file mode 100644
index 0000000000..42e9b0e6a5
--- /dev/null
+++ b/dom/media/mediasource/test/test_AutoRevocation.html
@@ -0,0 +1,40 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: auto-revocation</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(function() {
+  const ms = new MediaSource();
+  const o = URL.createObjectURL(ms);
+  const v = document.createElement("video");
+
+  v.addEventListener("error", () => {
+    ok(true, "ObjectURL should be auto-revoked");
+    SimpleTest.finish();
+  });
+
+  v.addEventListener("stalled", () => {
+    ok(false, "If auto-revocation is gone, please turn on TODOs in browser_mediaSourceURL.js");
+    SimpleTest.finish();
+  });
+
+  setTimeout(function() {
+    v.src = o;
+    v.preload = "auto";
+    document.body.appendChild(v);
+  }, 0);
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_BufferedSeek.html b/dom/media/mediasource/test/test_BufferedSeek.html
new file mode 100644
index 0000000000..039f56bc16
--- /dev/null
+++ b/dom/media/mediasource/test/test_BufferedSeek.html
@@ -0,0 +1,44 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: seeking in buffered range</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+
+  sb.appendBuffer(new Uint8Array(await fetchWithXHR("seek.webm")));
+
+  const target = 2;
+
+  v.addEventListener("loadedmetadata", () => {
+    ok(true, "received loadedmetadata");
+    v.currentTime = target;
+  });
+
+  let wasSeeking = false;
+
+  v.addEventListener("seeking", () => {
+    wasSeeking = true;
+    is(v.currentTime, target, "Video currentTime at target");
+  });
+
+  await once(v, "seeked");
+  ok(wasSeeking, "Received expected seeking and seeked events");
+  is(v.currentTime, target, "Video currentTime at target");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_BufferedSeek_mp4.html b/dom/media/mediasource/test/test_BufferedSeek_mp4.html
new file mode 100644
index 0000000000..e89e972c91
--- /dev/null
+++ b/dom/media/mediasource/test/test_BufferedSeek_mp4.html
@@ -0,0 +1,43 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: seeking in buffered range</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/mp4");
+
+  sb.appendBuffer(new Uint8Array(await fetchWithXHR("bipbop/bipbop2s.mp4")));
+
+  const target = 1.3;
+
+  await once(v, "loadedmetadata");
+  ok(true, "received loadedmetadata");
+  v.currentTime = target;
+
+  let wasSeeking = false;
+
+  v.addEventListener("seeking", () => {
+    wasSeeking = true;
+    is(v.currentTime, target, "Video currentTime at target");
+  });
+
+  await once(v, "seeked");
+  ok(wasSeeking, "Received expected seeking and seeked events");
+  is(v.currentTime, target, "Video currentTime at target");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_BufferingWait.html b/dom/media/mediasource/test/test_BufferingWait.html
new file mode 100644
index 0000000000..289ddfe4d2
--- /dev/null
+++ b/dom/media/mediasource/test/test_BufferingWait.html
@@ -0,0 +1,52 @@
+<!DOCTYPE html>
+<html><head>
+<meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: Don't get stuck buffering for too long when we have frames to show</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test"><script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  ms.addEventListener("sourceopen", () => ok(false, "No more sourceopen"));
+  const sb = ms.addSourceBuffer("video/webm");
+  ok(sb, "Create a SourceBuffer");
+
+  const arrayBuffer = await fetchWithXHR("seek.webm");
+  sb.addEventListener("error", e => {
+    ok(false, "Got Error: " + e);
+    SimpleTest.finish();
+  });
+  await loadSegment(sb, new Uint8Array(arrayBuffer, 0, 318));
+  await loadSegment(sb, new Uint8Array(arrayBuffer, 318, 25523 - 318));
+  await loadSegment(sb, new Uint8Array(arrayBuffer, 25523, 46712 - 25523));
+  /* Note - Missing |46712, 67833 - 46712| segment here corresponding to (0.8, 1.2] */
+  /* Note - Missing |67833, 88966 - 67833| segment here corresponding to (1.2, 1.6]  */
+  await loadSegment(sb, new Uint8Array(arrayBuffer, 88966));
+  // 0.767 is the time of the last video sample +- 40ms.
+  info("Playing video. It should play for a bit, then fire 'waiting'");
+  v.play();
+  await waitUntilTime(v, .767 - 0.04);
+  const firstStop = Date.now();
+  await loadSegment(sb, new Uint8Array(arrayBuffer, 46712, 67833 - 46712));
+  await waitUntilTime(v, 1.167 - 0.04);
+  const waitDuration = (Date.now() - firstStop) / 1000;
+  ok(waitDuration < 15, `Should not spend inordinate amount of time buffering: ${waitDuration}`);
+  SimpleTest.finish();
+  /* If we allow the rest of the stream to be played, we get stuck at
+     around 2s. See bug 1093133.
+  await once(v, "ended");
+  SimpleTest.finish();
+  await loadSegment(sb, new Uint8Array(arrayBuffer, 67833, 88966 - 67833));
+  */
+});
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_BufferingWait_mp4.html b/dom/media/mediasource/test/test_BufferingWait_mp4.html
new file mode 100644
index 0000000000..04e094a852
--- /dev/null
+++ b/dom/media/mediasource/test/test_BufferingWait_mp4.html
@@ -0,0 +1,49 @@
+<!DOCTYPE html>
+<html><head>
+<meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: Don't get stuck buffering for too long when we have frames to show</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test"><script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  ms.addEventListener("sourceopen", () => ok(false, "No more sourceopen"));
+  const sb = ms.addSourceBuffer("video/mp4");
+  ok(sb, "Create a SourceBuffer");
+
+  sb.addEventListener("error", e => {
+    ok(false, "Got Error: " + e);
+    SimpleTest.finish();
+  });
+  await fetchAndLoad(sb, "bipbop/bipbop", ["init"], ".mp4");
+  await fetchAndLoad(sb, "bipbop/bipbop", ["1"], ".m4s");
+  await fetchAndLoad(sb, "bipbop/bipbop", ["2"], ".m4s");
+  /* Note - Missing |bipbop3| segment here corresponding to (1.62, 2.41] */
+  /* Note - Missing |bipbop4| segment here corresponding to (2.41, 3.20]  */
+  await fetchAndLoad(sb, "bipbop/bipbop", ["5"], ".m4s");
+  // last audio sample has a start time of 1.578956s
+  info("Playing video. It should play for a bit, then fire 'waiting'");
+  v.play();
+  await waitUntilTime(v, 1.57895);
+  const firstStop = Date.now();
+  await fetchAndLoad(sb, "bipbop/bipbop", ["3"], ".m4s");
+  // last audio sample has a start time of 2.368435
+  await waitUntilTime(v, 2.36843);
+  const waitDuration = (Date.now() - firstStop) / 1000;
+  ok(waitDuration < 15, `Should not spend inordinate amount of time buffering: ${waitDuration}`);
+  await fetchAndLoad(sb, "bipbop/bipbop", ["4"], ".m4s");
+  ms.endOfStream();
+  await once(v, "ended");
+  SimpleTest.finish();
+});
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_ChangeType.html b/dom/media/mediasource/test/test_ChangeType.html
new file mode 100644
index 0000000000..690b9f61c4
--- /dev/null
+++ b/dom/media/mediasource/test/test_ChangeType.html
@@ -0,0 +1,84 @@
+<!DOCTYPE html>
+<html><head>
+<meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: changeType allow to change container and codec type</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test"><script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(function(ms, el) {
+  el.controls = true;
+  once(ms, "sourceopen").then(function() {
+    // Log events for debugging.
+    const events = ["suspend", "play", "canplay", "canplaythrough", "loadstart", "loadedmetadata",
+                    "loadeddata", "playing", "ended", "error", "stalled", "emptied", "abort",
+                    "waiting", "pause", "durationchange", "seeking", "seeked"];
+    function logEvent(e) {
+      info("got " + e.type + " event");
+    }
+    events.forEach(function(e) {
+      el.addEventListener(e, logEvent);
+    });
+
+    ok(true, "Receive a sourceopen event");
+
+    const videosb = ms.addSourceBuffer("video/mp4");
+    if (typeof videosb.changeType === "undefined") {
+      info("changeType API is not available");
+    }
+
+    el.addEventListener("error", e => {
+      ok(false, "should not fire '" + e.type + "' event");
+      SimpleTest.finish();
+    });
+    is(el.readyState, el.HAVE_NOTHING, "readyState is HAVE_NOTHING");
+    const loadedmetadataPromises = [];
+    loadedmetadataPromises.push(fetchAndLoad(videosb, "bipbop/bipbop", ["init"], ".mp4"));
+    loadedmetadataPromises.push(once(el, "loadedmetadata"));
+    Promise.all(loadedmetadataPromises)
+    .then(function() {
+      ok(true, "got loadedmetadata event");
+      const canplayPromises = [];
+      canplayPromises.push(once(el, "loadeddata"));
+      canplayPromises.push(once(el, "canplay"));
+      canplayPromises.push(fetchAndLoad(videosb, "bipbop/bipbop", range(1, 3), ".m4s"));
+      return Promise.all(canplayPromises);
+    })
+    .then(function() {
+      ok(true, "got canplay event");
+      el.play();
+      videosb.timestampOffset = el.buffered.end(0);
+      return fetchAndLoad(videosb, "bipbop/bipbop_480_624kbps-video", ["init"], ".mp4");
+    })
+    .then(fetchAndLoad.bind(null, videosb, "bipbop/bipbop_480_624kbps-video", range(1, 3), ".m4s"))
+    .then(function() {
+      videosb.timestampOffset = el.buffered.end(0);
+      try {
+        videosb.changeType("video/webm");
+      } catch (e) {
+        ok(false, "shouldn't throw an exception");
+        SimpleTest.finish();
+        throw e;
+      }
+      return fetchAndLoad(videosb, "bipbop/bipbop_300-3s", [""], ".webm");
+    })
+    .then(function() {
+      ms.endOfStream();
+      return once(el, "ended");
+    })
+    .then(function() {
+      ok(el.currentTime >= el.buffered.end(0), "played to the end");
+      SimpleTest.finish();
+    });
+  });
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_ChangeWhileWaitingOnMissingData_mp4.html b/dom/media/mediasource/test/test_ChangeWhileWaitingOnMissingData_mp4.html
new file mode 100644
index 0000000000..b5889da560
--- /dev/null
+++ b/dom/media/mediasource/test/test_ChangeWhileWaitingOnMissingData_mp4.html
@@ -0,0 +1,37 @@
+<!DOCTYPE html>
+<html><head>
+<meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: resume from waiting even after format change occurred</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test"><script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  const sb = ms.addSourceBuffer("video/mp4");
+  await fetchAndLoad(sb, "bipbop/bipbop_480_624kbps-video", ["init"], ".mp4");
+  await fetchAndLoad(sb, "bipbop/bipbop_480_624kbps-video", range(1, 3), ".m4s");
+  el.play();
+  // let seek to the last audio frame.
+  // The seek will complete and then playback will stall.
+  el.currentTime = 1.532517;
+  await Promise.all([once(el, "seeked"), once(el, "waiting")]);
+  info("seek completed");
+  await fetchAndLoad(sb, "bipbop/bipbop", ["init"], ".mp4");
+  await fetchAndLoad(sb, "bipbop/bipbop", range(1, 4), ".m4s");
+  ms.endOfStream();
+  await once(el, "ended");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_DifferentStreamStartTimes.html b/dom/media/mediasource/test/test_DifferentStreamStartTimes.html
new file mode 100644
index 0000000000..197e809e4f
--- /dev/null
+++ b/dom/media/mediasource/test/test_DifferentStreamStartTimes.html
@@ -0,0 +1,54 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: Mismatched stream start time playback test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  el.autoplay = true;
+  for (let i = 0; i <= 0.5; i += 0.1) {
+    const offset = i.toFixed(1);
+
+    info("----------------------");
+    info("Running test for mismatched stream start times with offset of: " + offset);
+    info("----------------------");
+
+    ms = new MediaSource();
+    el.removeAttribute("src");
+    el.src = URL.createObjectURL(ms);
+
+    await once(ms, "sourceopen");
+    logEvents(el);
+    const videosb = ms.addSourceBuffer("video/mp4");
+    ok(true, "Receive a sourceopen event");
+
+    el.addEventListener("error", e => {
+      ok(false, `should not fire ${e.type} event`);
+      SimpleTest.finish();
+    });
+
+    let p = once(el, "loadedmetadata");
+    await fetchAndLoad(videosb, "bipbop/bipbop_offset_" + offset + "-", ["init"], ".mp4");
+    await p;
+    ok(true, "got loadedmetadata event");
+
+    p = Promise.all(["loadeddata", "canplay", "play", "playing"].map(e => once(el, e)));
+    await fetchAndLoad(videosb, "bipbop/bipbop_offset_" + offset + "-", range(1, 2), ".m4s");
+    el.play();
+    await p;
+  }
+  ok(true, "got all required event");
+  SimpleTest.finish();
+});
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_DrainOnMissingData_mp4.html b/dom/media/mediasource/test/test_DrainOnMissingData_mp4.html
new file mode 100644
index 0000000000..ddc503aebf
--- /dev/null
+++ b/dom/media/mediasource/test/test_DrainOnMissingData_mp4.html
@@ -0,0 +1,49 @@
+<!DOCTYPE html>
+<html><head>
+<meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: |waiting| event when source data is missing</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test"><script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  const videosb = ms.addSourceBuffer("video/mp4");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", ["init"], ".mp4");
+  // Set appendWindowEnd to ensure we only have about 6 frames worth.
+  // We must feed at least 6 frames to pass the MDSM pre-roll.
+  videosb.appendWindowEnd = .4;
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", ["1"], ".m4s");
+  info("Invoking play()");
+  const p = once(el, "playing");
+  await el.play();
+  await p;
+  info("got playing");
+  await once(el, "waiting");
+  info("got waiting");
+  info("Loading more data");
+  // Waiting will be fired on the last frame +- 40ms.
+  isfuzzy(el.currentTime, videosb.buffered.end(0) - 1 / 30,
+          0.04, `Got a waiting event at ${el.currentTime}`);
+  videosb.appendWindowEnd = 1;
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", [1], ".m4s");
+  ms.endOfStream();
+  await once(el, "ended");
+  // These fuzz factors are bigger than they should be. We should investigate
+  // and fix them in bug 1137574.
+  is(el.duration, 0.801666, "Video has correct duration: " + el.duration);
+  is(el.currentTime, el.duration, "Video has correct currentTime.");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_DurationChange.html b/dom/media/mediasource/test/test_DurationChange.html
new file mode 100644
index 0000000000..3c83e83fa4
--- /dev/null
+++ b/dom/media/mediasource/test/test_DurationChange.html
@@ -0,0 +1,71 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: check that duration change behaves properly</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+
+  const arrayBuffer = await fetchWithXHR("seek.webm");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 0, 318));
+  await Promise.all([once(v, "loadedmetadata"), once(sb, "updateend")]);
+  is(v.duration, ms.duration, "video duration is mediasource one");
+  must_not_throw(() => ms.duration = 0, "duration = 0 is valid initially");
+  is(v.duration, 0, "reducing duration with no data buffered is valid");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 318));
+  // Adding more data will fire durationchange.
+  await once(sb, "updateend");
+  ok(true, "got updateend");
+  // XXX: Duration should be exactly 4.0, see bug 1065207.
+  ok(Math.abs(v.duration - 4) <= 0.002, "Video has correct duration");
+  must_throw(() => ms.duration = 0,
+             "Must use remove for range removal",
+             "InvalidStateError");
+  ok(Math.abs(v.duration - 4) <= 0.002, "Video has correct duration");
+  must_not_throw(() => ms.duration = 10, "setting duration past data is valid");
+  is(v.duration, 10, "extending duration is always valid");
+  // The last sample has a start time of 3.967000s and a end time of 4.001 (see bug 1065207).
+  must_not_throw(() => ms.duration = 3.967000,
+                 "setting duration with >= highest frame presentation time is valid");
+  is(v.duration, sb.buffered.end(0),
+     "duration is the highest end time reported by the buffered attribute ");
+  must_not_throw(() => ms.duration = 3.97,
+                 "setting duration with >= highest frame presentation time is valid");
+  is(v.duration, sb.buffered.end(0),
+     "duration is the highest end time reported by the buffered attribute ");
+  must_throw(() => ms.duration = 3.96,
+             "setting duration with < highest frame presentation time is not valid",
+             "InvalidStateError");
+  is(v.duration, sb.buffered.end(0),
+     "duration is the highest end time reported by the buffered attribute ");
+  must_throw(() => ms.duration = -1, "can't set a negative duration", "TypeError");
+  sb.remove(sb.buffered.end(0), Infinity);
+  is(sb.updating, true, "updating is true");
+  must_throw(() => ms.duration = Infinity,
+             "setting the duration while updating is not allowed",
+             "InvalidStateError");
+  must_throw(() => sb.abort(),
+             "Can't use abort while range removal is in progress",
+             "InvalidStateError");
+  is(v.duration, sb.buffered.end(0),
+     "duration is the highest end time reported by the buffered attribute ");
+  await once(sb, "updateend");
+  ms.endOfStream();
+  await once(ms, "sourceended");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_DurationUpdated.html b/dom/media/mediasource/test/test_DurationUpdated.html
new file mode 100644
index 0000000000..eb54e76c90
--- /dev/null
+++ b/dom/media/mediasource/test/test_DurationUpdated.html
@@ -0,0 +1,48 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: append data and check that mediasource duration got updated</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+
+  let durationChangeCount = 0;
+  v.addEventListener("durationchange", () => durationChangeCount++);
+
+  const arrayBuffer = await fetchWithXHR("seek.webm");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 0, 318));
+
+  // Adding the first init segment will fire a durationchange.
+  await Promise.all([once(sb, "updateend"), once(v, "loadedmetadata")]);
+  ok(true, "got loadedmetadata");
+  // Set mediasource duration to 0, so future appendBuffer
+  // will update the mediasource duration.
+  // Changing the duration will fire a durationchange.
+  ms.duration = 0;
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 318));
+  // Adding more data will fire durationchange.
+  await once(sb, "updateend");
+  ok(true, "got updateend");
+  // this will not fire durationchange as new duration == old duration
+  ms.endOfStream();
+  await once(ms, "sourceended");
+  is(durationChangeCount, 3, "durationchange not fired as many times as expected");
+  // XXX: Duration should be exactly 4.0, see bug 1065207.
+  ok(Math.abs(v.duration - 4) <= 0.002, "Video has correct duration");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_DurationUpdated_mp4.html b/dom/media/mediasource/test/test_DurationUpdated_mp4.html
new file mode 100644
index 0000000000..f263264b09
--- /dev/null
+++ b/dom/media/mediasource/test/test_DurationUpdated_mp4.html
@@ -0,0 +1,47 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: append data and check that mediasource duration got updated</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/mp4");
+
+  let durationChangeCount = 0;
+  v.addEventListener("durationchange", () => durationChangeCount++);
+
+  const arrayBuffer = await fetchWithXHR("bipbop/bipbop2s.mp4");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 0, 1395));
+
+  // Adding the first init segment will fire a durationchange.
+  await Promise.all([once(sb, "updateend"), once(v, "loadedmetadata")]);
+  ok(true, "got loadedmetadata");
+  // Set mediasource duration to 0, so future appendBuffer
+  // will update the mediasource duration.
+  // Changing the duration will fire a durationchange.
+  ms.duration = 0;
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 1395));
+  // Adding more data will fire durationchange.
+  await once(sb, "updateend");
+  ok(true, "got updateend");
+  // this will not fire durationchange as new duration == old duration
+  ms.endOfStream();
+  await once(ms, "sourceended");
+  is(durationChangeCount, 3, "durationchange not fired as many times as expected");
+  is(v.duration, 1.696666, "Video has correct duration");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_EndOfStream.html b/dom/media/mediasource/test/test_EndOfStream.html
new file mode 100644
index 0000000000..b926869f1f
--- /dev/null
+++ b/dom/media/mediasource/test/test_EndOfStream.html
@@ -0,0 +1,29 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: endOfStream call after an appendBuffer</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+
+  sb.appendBuffer(new Uint8Array(await fetchWithXHR("seek.webm"), 0, 88966));
+  await once(sb, "updateend");
+  await wait(0);
+  must_not_throw(() => ms.endOfStream(), "MediaSource.endOfStream succeeded");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_EndOfStream_mp4.html b/dom/media/mediasource/test/test_EndOfStream_mp4.html
new file mode 100644
index 0000000000..9319b80390
--- /dev/null
+++ b/dom/media/mediasource/test/test_EndOfStream_mp4.html
@@ -0,0 +1,29 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: endOfStream call after an appendBuffer</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/mp4");
+
+  sb.appendBuffer(new Uint8Array(await fetchWithXHR("bipbop/bipbop2s.mp4")));
+  await once(sb, "updateend");
+  await wait(0);
+  must_not_throw(() => ms.endOfStream(), "MediaSource.endOfStream succeeded");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_EndedEvent.html b/dom/media/mediasource/test/test_EndedEvent.html
new file mode 100644
index 0000000000..ee43fa8cf5
--- /dev/null
+++ b/dom/media/mediasource/test/test_EndedEvent.html
@@ -0,0 +1,31 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: basic functionality</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, el) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+  sb.appendBuffer(new Uint8Array(await fetchWithXHR("seek.webm")));
+  sb.addEventListener("updateend", () => ms.endOfStream());
+
+  // Test "ended" is fired when seeking to the end of the media
+  // once the duration is known.
+  ms.onsourceended = () => el.currentTime = el.duration;
+  await once(el, "ended");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_Eviction_mp4.html b/dom/media/mediasource/test/test_Eviction_mp4.html
new file mode 100644
index 0000000000..e336fae4c7
--- /dev/null
+++ b/dom/media/mediasource/test/test_Eviction_mp4.html
@@ -0,0 +1,63 @@
+<!DOCTYPE html>
+<html><head>
+<meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: QuotaExceededError when source buffer is full</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test"><script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+// We fill up the source buffer with audio data until the buffer is full.
+// We ensure that QuotaExceededError is thrown once the buffer is full.
+// We then seek to half the content. By that time, another appendBuffer must succeed
+// as the auto-eviction would succeed (removing all data prior currentTime)
+
+addMSEPrefs(
+  ["media.mediasource.eviction_threshold.audio", 524288],
+  ["media.dormant-on-pause-timeout-ms", -1] // FIXME: bug 1319292
+);
+
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  const audiosb = ms.addSourceBuffer("audio/mp4");
+  audiosb.mode = "sequence";
+  await fetchAndLoad(audiosb, "bipbop/bipbop_audio", ["init"], ".mp4");
+  const audioBuffer = await fetchWithXHR("bipbop/bipbop_audio1.m4s");
+
+  await must_reject(async () => {
+    // We are appending data repeatedly in sequence mode, there should be no gaps.
+    while (true) {
+      ok(audiosb.buffered.length <= 1, "there should be no gap in buffered ranges.");
+      audiosb.appendBuffer(audioBuffer);
+      await once(audiosb, "updateend");
+    }
+  },
+  "Fill up SourceBuffer by appending data until an exception is thrown.",
+  "QuotaExceededError");
+
+  is(audiosb.buffered.end(0), el.duration, "Duration is end of buffered range");
+  const seekTime = audiosb.buffered.end(0) / 2;
+  el.currentTime = seekTime;
+  await once(el, "seeked");
+  dump("dump: seeked to " + seekTime);
+  is(el.currentTime, seekTime, "correctly seeked to " + seekTime);
+  try {
+    audiosb.appendBuffer(audioBuffer);
+    await once(audiosb, "update");
+    ok(true, "appendBuffer succeeded");
+  } catch (ex) {
+    ok(false, "Shouldn't throw another time when data can be evicted");
+    dump(JSON.stringify(await SpecialPowers.wrap(el).mozRequestDebugInfo()));
+  }
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_ExperimentalAsync.html b/dom/media/mediasource/test/test_ExperimentalAsync.html
new file mode 100644
index 0000000000..6617716f26
--- /dev/null
+++ b/dom/media/mediasource/test/test_ExperimentalAsync.html
@@ -0,0 +1,102 @@
+<!DOCTYPE html>
+<html><head>
+<meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: testing removeAsync and appendBufferAsync</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test"><script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+addMSEPrefs(
+  ["media.mediasource.eviction_threshold.audio", 524288],
+  ["media.dormant-on-pause-timeout-ms", -1], // FIXME: bug 1319292
+  ["media.mediasource.experimental.enabled", true]
+);
+
+// We fill up the source buffer with audio data until the buffer is full.
+// We ensure that QuotaExceededError is thrown once the buffer is full.
+// We then seek to half the content. By that time, another appendBuffer must succeed
+// as the auto-eviction would succeed (removing all data prior currentTime)
+// The test then fills the audio buffer and plays until the end.
+
+// Fill up the SourceBuffer by appending data repeatedly via doAppendDataFunc until
+// an exception is thrown.
+async function fillUpSourceBuffer(sourceBuffer, doAppendDataFunc, onCaughtExceptionCallback) {
+  try {
+    // We are appending data repeatedly in sequence mode, there should be no gaps.
+    while (true) {
+      ok(sourceBuffer.buffered.length <= 1, "there should be no gap in buffered ranges.");
+      await doAppendDataFunc();
+    }
+  } catch (ex) {
+    ok(true, "appendBuffer promise got rejected");
+    onCaughtExceptionCallback(ex);
+  }
+}
+
+runWithMSE(async function(ms, el) {
+  el.controls = true;
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  const audiosb = ms.addSourceBuffer("audio/mp4");
+
+  // Test removeAsync
+  audiosb.mode = "sequence";
+  const audioInitBuffer = await fetchWithXHR("bipbop/bipbop_audioinit.mp4");
+  await audiosb.appendBufferAsync(audioInitBuffer);
+  const audioBuffer = await fetchWithXHR("bipbop/bipbop_audio1.m4s");
+  fillUpSourceBuffer(audiosb,
+    function() { // doAppendDataFunc
+      return audiosb.appendBufferAsync(audioBuffer);
+    },
+    async function(ex1) { // onCaughtExceptionCallback
+      is(ex1.name, "QuotaExceededError", "QuotaExceededError thrown");
+      is(audiosb.buffered.end(0), el.duration, "Duration is end of buffered range");
+      const seekTime = audiosb.buffered.end(0) / 2;
+      el.currentTime = seekTime;
+      await once(el, "seeked");
+      dump("dump: seeked to " + seekTime);
+      is(el.currentTime, seekTime, "correctly seeked to " + seekTime);
+      await audiosb.appendBufferAsync(audioBuffer).catch(async function(ex2) {
+        ok(false, "Shouldn't throw another time when data can be evicted");
+        dump(JSON.stringify(await SpecialPowers.wrap(el).mozRequestDebugInfo()));
+        SimpleTest.finish();
+      });
+      // Test that an error in remove return a rejected promise
+      await audiosb.removeAsync(5, 0).catch(async function(ex3) {
+        ok(true, "remove promise got rejected with end <= start");
+        is(ex3.name, "TypeError");
+        await audiosb.removeAsync(ms.duration + 1, Infinity).catch(async function(ex4) {
+          ok(true, "remove promise got rejected with start > duration");
+          is(ex4.name, "TypeError");
+          await audiosb.removeAsync(0, Infinity).catch(function(ex5) {
+            ok(false, "shouldn't throw");
+          });
+          ok(true, "remove succeeded");
+          is(audiosb.buffered.length, 0, "buffered should be empty");
+          audiosb.mode = "segment";
+          audiosb.timestampOffset = 0;
+          el.currentTime = 0;
+          await fetchAndLoadAsync(audiosb, "bipbop/bipbop_audio", range(1, 4), ".m4s");
+          ms.endOfStream();
+          el.play();
+          await once(el, "ended");
+          is(el.currentTime, el.duration, "played to the end");
+          SimpleTest.finish();
+          throw ex4; // ensure we don't fallback on lines below.
+        });
+        ok(false, "should have returned an error");
+      });
+      ok(false, "should have returned an error");
+    }
+  );
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_FrameSelection.html b/dom/media/mediasource/test/test_FrameSelection.html
new file mode 100644
index 0000000000..3e696841c2
--- /dev/null
+++ b/dom/media/mediasource/test/test_FrameSelection.html
@@ -0,0 +1,64 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: verify correct frames selected for given position</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+
+  let arrayBuffer = await fetchWithXHR("seek.webm");
+  let p = once(v, "loadedmetadata");
+  // Append entire file covering range [0, 4].
+  sb.appendBuffer(new Uint8Array(arrayBuffer));
+  await p;
+  is(v.currentTime, 0, "currentTime has correct initial value");
+  is(v.videoWidth, 320, "videoWidth has correct initial value");
+  is(v.videoHeight, 240, "videoHeight has correct initial value");
+
+  arrayBuffer = await fetchWithXHR("seek_lowres.webm");
+  // Append initialization segment.
+  info("Appending low-res init segment");
+  p = once(sb, "updateend");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 0, 438));
+  await p;
+
+  info("Appending low-res range [2,4]");
+  // Append media segment covering range [2, 4].
+  p = once(sb, "updateend");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 51003));
+  await p;
+
+  ms.endOfStream();
+
+  info("Seeking to t=3");
+  p = Promise.all([once(v, "seeked"), once(v, "resize")]);
+  v.currentTime = 3;
+  await p;
+  is(v.currentTime, 3, "Video currentTime at target");
+  is(v.videoWidth, 160, "videoWidth has correct low-res value");
+  is(v.videoHeight, 120, "videoHeight has correct low-res value");
+
+  info("Seeking to t=1");
+  p = Promise.all([once(v, "seeked"), once(v, "resize")]);
+  v.currentTime = 1;
+  await p;
+  is(v.currentTime, 1, "Video currentTime at target");
+  is(v.videoWidth, 320, "videoWidth has correct high-res value");
+  is(v.videoHeight, 240, "videoHeight has correct high-res value");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_FrameSelection_mp4.html b/dom/media/mediasource/test/test_FrameSelection_mp4.html
new file mode 100644
index 0000000000..628b4bf0e9
--- /dev/null
+++ b/dom/media/mediasource/test/test_FrameSelection_mp4.html
@@ -0,0 +1,49 @@
+<!DOCTYPE html>
+<html><head>
+<meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: Don't get stuck buffering for too long when we have frames to show</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test"><script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+// This test loads partial video, plays and waits until playback stalls.
+// It then loads only 3 frames of a video at higher resolution.
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  ms.addEventListener("sourceopen", () => ok(false, "No more sourceopen"));
+  const sb = ms.addSourceBuffer("video/mp4");
+  ok(sb, "Create a SourceBuffer");
+  logEvents(v);
+  sb.addEventListener("error", e => {
+    ok(false, `should not fire ${e.type} event`);
+    SimpleTest.finish();
+  });
+  await fetchAndLoad(sb, "bipbop/bipbop", ["init"], ".mp4");
+  const p = once(v, "loadeddata");
+  await fetchAndLoad(sb, "bipbop/bipbop", range(1, 3), ".m4s");
+  await p;
+  is(sb.buffered.length, 1, "continuous range");
+  v.play();
+  // We have nothing to play, waiting will be fired.
+  await waitUntilTime(v, 1.5);
+  await fetchAndLoad(sb, "bipbop/bipbop_480_624kbps-video", ["init"], ".mp4");
+  sb.timestampOffset = 1.601666; // End of the video track buffered - time of first video sample (0.095).
+  sb.appendWindowEnd = 1.796677; // Only allow room for three extra video frames (we need 3 as this video has b-frames).
+  await fetchAndLoad(sb, "bipbop/bipbop_480_624kbps-video", ["1"], ".m4s");
+  ms.endOfStream();
+  await Promise.all([once(ms, "sourceended"), once(v, "playing"), once(v, "ended")]);
+  is(v.videoWidth, 640, "has proper width");
+  is(v.videoHeight, 480, "has proper height");
+  SimpleTest.finish();
+});
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_HEAAC_extradata.html b/dom/media/mediasource/test/test_HEAAC_extradata.html
new file mode 100644
index 0000000000..9fbbec8d72
--- /dev/null
+++ b/dom/media/mediasource/test/test_HEAAC_extradata.html
@@ -0,0 +1,89 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>HE-AAC decoding test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+
+SimpleTest.waitForExplicitFinish();
+
+const SOURCE_FILE = "whitenoise-he-aac-5s.mp4";
+
+// This test checks when decoding HE-AAC using MediaSource or HTTP playback, the
+// audio is decoded correctly (in particular with the SBR part). This means
+// that the extradata describing the encoded AAC stream have been communicated
+// correctly to the audio decoder. For this, we check that there is energy
+// above 10kHz using the Web Audio API when playing white noise, which has
+// maximum energy accross the audible spectrum.
+
+// Return the index corresponding for a particular frequency in an array
+// containing frequency data from a FFT.
+function binIndexForFrequency(frequency, fftSize, sampleRate) {
+  return (1 + Math.round((frequency * fftSize) / sampleRate));
+}
+
+async function checkHighFrequencyContent(element) {
+  const ac = new AudioContext();
+  await ac.resume();
+  const mediaElementSource = ac.createMediaElementSource(element);
+  const analyser = new AnalyserNode(ac);
+
+  // Undo the volume scaling applied globally during test. This is fine because
+  // the audio isn't routed to an actual audio output device in this test, it's
+  // just analyzed with the Web Audio API.
+  const gain = new GainNode(ac);
+  const testVolumeScaling =
+    parseFloat(SpecialPowers.getCharPref("media.volume_scale"));
+  gain.gain.value = 1 / parseFloat(testVolumeScaling);
+  mediaElementSource.connect(gain).connect(analyser)
+
+  const spectrum = new Float32Array(analyser.frequencyBinCount);
+  const indexFor15kHz =
+    binIndexForFrequency(15000, analyser.fftSize, ac.sampleRate);
+  // Wait a few hundreds of milliseconds
+  while (!element.ended) {
+    await once(element, "timeupdate");
+    analyser.getFloatFrequencyData(spectrum);
+    if (spectrum[indexFor15kHz] > -50) {
+      ok(spectrum[indexFor15kHz] > -50,
+          `Energy present at 15kHz (bin index: ${indexFor15kHz}) when playing white noise encoded in HE-AAC ${spectrum[indexFor15kHz]}`);
+      return;
+    }
+  }
+  ok(false,
+      `No energy present at 15kHz (bin index: ${indexFor15kHz}) when playing white noise encoded in HE-AAC (last value ${spectrum[indexFor15kHz]})`);
+}
+
+runWithMSE(async (ms, el) => {
+  // First check with MSE playback
+  el.controls = true;
+  await once(ms, "sourceopen");
+
+  const audiosb = ms.addSourceBuffer('audio/mp4; codecs="mp4a.40.5"');
+  await fetchAndLoad(audiosb, SOURCE_FILE, [""], "");
+  ms.endOfStream();
+  el.play();
+  once(el, "playing");
+
+  await checkHighFrequencyContent(el);
+
+  // Redo the same test, with HTTP playback
+  el.src = SOURCE_FILE;
+  el.play();
+  once(el, "playing");
+
+  await checkHighFrequencyContent(el);
+
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_HaveMetadataUnbufferedSeek.html b/dom/media/mediasource/test/test_HaveMetadataUnbufferedSeek.html
new file mode 100644
index 0000000000..dd1b252f01
--- /dev/null
+++ b/dom/media/mediasource/test/test_HaveMetadataUnbufferedSeek.html
@@ -0,0 +1,38 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: seekable attribute before end of stream</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+
+  const arrayBuffer = await fetchWithXHR("seek.webm");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 0, 67833));
+
+  const target = 2;
+
+  await once(v, "loadeddata");
+  ok(v.readyState >= v.HAVE_CURRENT_DATA, "readyState is >= CURRENT_DATA");
+  v.currentTime = target;
+
+  await once(v, "seeking");
+  is(v.readyState, v.HAVE_METADATA, "readyState is HAVE_METADATA");
+  sb.appendBuffer(new Uint8Array(await fetchWithXHR("seek.webm"), 67833));
+  await once(v, "seeked");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_HaveMetadataUnbufferedSeek_mp4.html b/dom/media/mediasource/test/test_HaveMetadataUnbufferedSeek_mp4.html
new file mode 100644
index 0000000000..9b8e885cda
--- /dev/null
+++ b/dom/media/mediasource/test/test_HaveMetadataUnbufferedSeek_mp4.html
@@ -0,0 +1,42 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: seekable attribute before end of stream</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/mp4");
+
+  const arrayBuffer = await fetchWithXHR("bipbop/bipbop2s.mp4");
+  // 25819 is the offset of the first media segment's end
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 0, 25819));
+
+  const target = 1.3;
+
+  await once(v, "loadeddata");
+  ok(v.readyState >= v.HAVE_CURRENT_DATA, "readyState is >= CURRENT_DATA");
+  v.currentTime = target;
+
+  await once(v, "seeking");
+  is(v.readyState, v.HAVE_METADATA);
+  // 25819 is the offset of the first media segment's end
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 25819));
+  await once(sb, "updateend");
+  ms.endOfStream();
+  await once(v, "seeked");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_InputBufferIsCleared.html b/dom/media/mediasource/test/test_InputBufferIsCleared.html
new file mode 100644
index 0000000000..bad9a0c558
--- /dev/null
+++ b/dom/media/mediasource/test/test_InputBufferIsCleared.html
@@ -0,0 +1,58 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: input buffer is cleared as expected (bug 1697476)</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+// Test bug 1697476 is fixed. We do this by appending a number of segments with
+// trailing `skip` boxes. If the bug is fixed, then the data from these appends
+// will eventually be cleared from memory. If not fixed, we leak that memory.
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/mp4");
+  await fetchAndLoad(sb, "bipbop/bipbop_video", ["init"], ".mp4");
+  // Load ~1mb of media.
+  await fetchAndLoad(sb, "bipbop/bipbop_trailing_skip_box_video", ["1"], ".m4s");
+  // Load ~1mb more media several more times.
+  const numberOfAppends = 5;
+  for (let i = 1; i < numberOfAppends; ++i) {
+    sb.timestampOffset = v.buffered.end(0);
+    await fetchAndLoad(sb, "bipbop/bipbop_trailing_skip_box_video", ["1"], ".m4s");
+  }
+
+  // Grab a memory report. We'll use this to make sure we're not accumulating
+  // too much data in our buffers.
+  const mgr = SpecialPowers.Cc["@mozilla.org/memory-reporter-manager;1"]
+      .getService(SpecialPowers.Ci.nsIMemoryReporterManager);
+
+  let amount = 0;
+  const handleReport = (aProcess, aPath, aKind, aUnits, aAmount) => {
+    if (aPath == "explicit/media/resources") {
+      amount += aAmount;
+    }
+  };
+
+  await new Promise(r => mgr.getReports(handleReport, null, r, null, /* anonymized = */ false));
+  ok(true, "Yay didn't crash!");
+  ok(amount !== undefined, "Got media resources amount");
+  const sgementSize = 1023860;
+  // Set the limit to be equal to the total data we appended. If we're not
+  // clearing buffers, we'll have all the data from the appends + some other
+  // data, so will fail.
+  const limit = sgementSize * numberOfAppends - 1;
+  ok(amount < limit, `Should have less than ${limit} bytes of media usage. Got ${amount} bytes.`);
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_LiveSeekable.html b/dom/media/mediasource/test/test_LiveSeekable.html
new file mode 100644
index 0000000000..b981ceba00
--- /dev/null
+++ b/dom/media/mediasource/test/test_LiveSeekable.html
@@ -0,0 +1,76 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: live seekable range</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+
+  // Load data with a +2 offset so that we can distinguish buffered range start
+  // and seekable range start.
+  sb.timestampOffset = 2;
+  const p = once(v, "loadedmetadata");
+  await fetchAndLoad(sb, "seek", [""], ".webm");
+  await p;
+  ms.duration = Infinity;
+  sb.abort();
+  is(sb.buffered.length, 1, "continuous buffered range");
+  is(sb.buffered.start(0), 2, "buffered range start at timestamp offset");
+  is(sb.buffered.end(0), 6.001, "buffered range end at original duration + timestamp offset");
+  is(v.seekable.length, 1, "continuous seekable range");
+  is(v.seekable.start(0), 0, "seekable range start at 0");
+  is(v.seekable.end(0), sb.buffered.end(0), "seekable range end at buffered end");
+
+  // LiveSeekableRange.start < buffered.start
+  ms.setLiveSeekableRange(1, 5);
+  is(v.seekable.length, 1, "continuous seekable range");
+  is(v.seekable.start(0), 1, "seekable range start at live range start");
+  is(v.seekable.end(0), sb.buffered.end(0), "seekable range end at buffered end");
+
+  ms.clearLiveSeekableRange();
+  is(v.seekable.length, 1, "continuous seekable range");
+  is(v.seekable.start(0), 0, "seekable range start at 0");
+  is(v.seekable.end(0), sb.buffered.end(0), "seekable range end at buffered end");
+
+  // LiveSeekableRange.end > buffered.end
+  ms.setLiveSeekableRange(1, 8);
+  is(v.seekable.start(0), 1, "seekable range start at live range start");
+  is(v.seekable.end(0), 8, "seekable range end at live range end");
+
+  // LiveSeekableRange.start > buffered.start
+  // LiveSeekableRange.end < buffered.end
+  ms.setLiveSeekableRange(3, 5);
+  is(v.seekable.start(0), sb.buffered.start(0), "seekable range start at buffered start");
+  is(v.seekable.end(0), sb.buffered.end(0), "seekable range end at live range end");
+
+  // LiveSeekableRange.start > buffered.end
+  ms.setLiveSeekableRange(8, 10);
+  is(v.seekable.start(0), sb.buffered.start(0), "seekable range start at buffered start");
+  is(v.seekable.end(0), 10, "seekable range end at live range end");
+
+  // LiveSeekableRange.end < buffered.start
+  ms.setLiveSeekableRange(0, 2);
+  is(v.seekable.start(0), 0, "seekable range start at live range start");
+  is(v.seekable.end(0), sb.buffered.end(0), "seekable range end at buffered end");
+
+  must_throw(() => ms.setLiveSeekableRange(2, 0),
+             "must thow if start > end",
+             "TypeError");
+
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_LoadedDataFired_mp4.html b/dom/media/mediasource/test/test_LoadedDataFired_mp4.html
new file mode 100644
index 0000000000..476303d4fd
--- /dev/null
+++ b/dom/media/mediasource/test/test_LoadedDataFired_mp4.html
@@ -0,0 +1,57 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: Check that playback only starts once we have data at time = 0</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  el.addEventListener("loadeddata", () => {
+    ok(el.buffered.length, "data is buffered");
+    is(el.buffered.start(0), 0, "must fire loadeddata when data has been loaded");
+    is(el.currentTime, 0, "must fire loadeddata at start");
+  });
+  el.addEventListener("playing", () => {
+    ok(el.buffered.length, "data is buffered");
+    is(el.buffered.start(0), 0, "must fire playing when data has been loaded");
+    ok(el.currentTime >= 0, "must have started playback");
+  });
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  const videosb = ms.addSourceBuffer("video/mp4");
+  is(el.readyState, el.HAVE_NOTHING, "readyState is HAVE_NOTHING");
+  let p = once(el, "loadedmetadata");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", ["init"], ".mp4");
+  await p;
+  videosb.appendWindowStart = 2;
+  videosb.appendWindowEnd = 4;
+  is(el.readyState, el.HAVE_METADATA, "readyState is HAVE_METADATA");
+  // Load [2.4, 3.968344). 2.4 as it's the first keyframe after 2s and
+  // 3.968344 as the last frame ends after 4s.
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(1, 8), ".m4s");
+  is(el.readyState, el.HAVE_METADATA, "readyState is HAVE_METADATA");
+  // test that appendWindowEnd did its job.
+  ok(el.buffered.start(0) >= 2, "no data can be found prior appendWindowStart");
+  ok(el.buffered.end(el.buffered.length - 1) <= 4, "no data can be found beyond appendWindowEnd");
+  el.play();
+  await once(el, "play");
+  videosb.appendWindowStart = 0;
+  p = once(el, "playing");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(1, 8), ".m4s");
+  await p;
+  ok(true, "playing");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_LoadedMetadataFired.html b/dom/media/mediasource/test/test_LoadedMetadataFired.html
new file mode 100644
index 0000000000..68030dbe2f
--- /dev/null
+++ b/dom/media/mediasource/test/test_LoadedMetadataFired.html
@@ -0,0 +1,31 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: append initialization only</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+
+  sb.appendBuffer(new Uint8Array(await fetchWithXHR("seek.webm"), 0, 318));
+  v.play();
+  await once(v, "loadedmetadata");
+  ok(true, "Got loadedmetadata event");
+  is(v.videoWidth, 320, "videoWidth has correct initial value");
+  is(v.videoHeight, 240, "videoHeight has correct initial value");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_LoadedMetadataFired_mp4.html b/dom/media/mediasource/test/test_LoadedMetadataFired_mp4.html
new file mode 100644
index 0000000000..0934907578
--- /dev/null
+++ b/dom/media/mediasource/test/test_LoadedMetadataFired_mp4.html
@@ -0,0 +1,31 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: append initialization only</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/mp4");
+
+  sb.appendBuffer(new Uint8Array(await fetchWithXHR("bipbop/bipbop2s.mp4"), 0, 1395));
+  v.play();
+  await once(v, "loadedmetadata");
+  ok(true, "Got loadedmetadata event");
+  is(v.videoWidth, 400, "videoWidth has correct initial value");
+  is(v.videoHeight, 300, "videoHeight has correct initial value");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_MediaSource.html b/dom/media/mediasource/test/test_MediaSource.html
new file mode 100644
index 0000000000..9bdaa0d30b
--- /dev/null
+++ b/dom/media/mediasource/test/test_MediaSource.html
@@ -0,0 +1,92 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: basic functionality</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  SimpleTest.doesThrow(() => new SourceBuffer, "new SourceBuffer should fail");
+  SimpleTest.doesThrow(() => new SourceBufferList, "new SourceBufferList direct should fail");
+
+  ok(ms instanceof EventTarget, "MediaSource must be an EventTarget");
+  is(ms.readyState, "closed", "New MediaSource must be in closed state");
+
+  // Wrapper creation, tests for leaks.
+  SpecialPowers.wrap(ms);
+
+  // Set an expando to force wrapper creation, tests for leaks.
+  ms.foo = null;
+
+  ok(URL.createObjectURL(ms), "Create an objectURL from the MediaSource");
+
+  let loadedmetadataCount = 0;
+  let updatestartCount = 0;
+  let updateendCount = 0;
+  let updateCount = 0;
+
+  ok(MediaSource.isTypeSupported("video/webm; codecs=vp8"), "VP8 MSE is always supported");
+  ok(MediaSource.isTypeSupported("audio/webm"), "Audio MSE is always supported");
+
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  is(ms.readyState, "open", "MediaSource must be in open state after sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+  ok(sb, "Create a SourceBuffer");
+  is(ms.sourceBuffers.length, 1, "MediaSource.sourceBuffers is expected length");
+  is(ms.sourceBuffers[0], sb, "SourceBuffer in list matches our SourceBuffer");
+  is(ms.activeSourceBuffers.length, 0, "MediaSource.activeSourceBuffers is expected length");
+
+  sb.appendBuffer(new Uint8Array(await fetchWithXHR("seek.webm")));
+  is(sb.updating, true, "SourceBuffer.updating is expected value after appendBuffer");
+
+  sb.addEventListener("update", () => {
+    is(sb.updating, false, "SourceBuffer.updating is expected value in update event");
+    updateCount++;
+    /* Ensure that we endOfStream on the first update event only as endOfStream can
+       raise more if the duration of the last buffered range and the intial duration
+       differ. See bug 1065207 */
+    if (updateCount == 1) {
+      ms.endOfStream();
+    }
+  });
+
+  sb.addEventListener("updatestart", () => updatestartCount++);
+
+  sb.addEventListener("updateend", () => {
+    is(ms.activeSourceBuffers[0], sb, "SourceBuffer in active list matches our SourceBuffer");
+    is(sb.updating, false, "SourceBuffer.updating is expected value in updateend event");
+    updateendCount++;
+    v.play();
+  });
+
+  ms.addEventListener("sourceended", () => {
+    ok(true, "Receive a sourceended event");
+    is(ms.readyState, "ended", "MediaSource must be in ended state after sourceended");
+  });
+
+  v.addEventListener("loadedmetadata", () => loadedmetadataCount++);
+
+  await once(v, "ended");
+  // XXX: Duration should be exactly 4.0, see bug 1065207.
+  ok(Math.abs(v.duration - 4) <= 0.002, "Video has correct duration");
+  ok(Math.abs(v.currentTime - 4) <= 0.002, "Video has played to end");
+  // XXX: 2 update events can be received dueto duration differences, see bug 1065207.
+  ok(updateCount == 1 || updateCount == 2, "update event received");
+  ok(updateendCount == 1 || updateendCount == 2, "updateend event received");
+  ok(updatestartCount == 1 || updatestartCount == 2, "updatestart event received");
+  is(loadedmetadataCount, 1, "loadedmetadata event received");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_MediaSource_capture_gc.html b/dom/media/mediasource/test/test_MediaSource_capture_gc.html
new file mode 100644
index 0000000000..d986a6f9ac
--- /dev/null
+++ b/dom/media/mediasource/test/test_MediaSource_capture_gc.html
@@ -0,0 +1,72 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test garbage collection of captured stream, when playing a MediaSource</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+  <script type="text/javascript" src="mediasource.js"></script>
+</head>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+function forceGC() {
+  SpecialPowers.gc();
+  SpecialPowers.forceGC();
+  SpecialPowers.forceCC();
+}
+
+SimpleTest.waitForExplicitFinish();
+
+window.onload = async function() {
+// Create an infinite source using a MediaSource
+let el = document.createElement("audio");
+const ms = new MediaSource();
+el.src = URL.createObjectURL(ms);
+await once(ms, "sourceopen");
+const sb = ms.addSourceBuffer("video/mp4");
+await fetchAndLoad(sb, "bipbop/bipbop_audio", ["init"], ".mp4");
+await fetchAndLoad(sb, "bipbop/bipbop_audio", range(1, 11), ".m4s");
+setInterval(async function() {
+  sb.timestampOffset =  sb.buffered.end(sb.buffered.length - 1);
+  await fetchAndLoad(sb, "bipbop/bipbop_audio", range(1, 11), ".m4s");
+}, 8000);
+el.play();
+
+// Analyze the media element output.
+const ac = new AudioContext;
+const analyzer = ac.createAnalyser();
+
+// bug 1703603
+const stream = el.mozCaptureStreamUntilEnded();
+const mss = ac.createMediaStreamSource(stream);
+const gain = ac.createGain();
+// compensate mochitest volume scaling, but don't connect to the AudioContext's
+// destination to avoid noise during the test
+gain.gain.value = 90;
+mss.connect(gain).connect(analyzer);
+
+
+// Drop the media element reference: it is supposed to be kept alive by the
+// AudioContext via the `MediaStream`.
+el = null;
+
+// check whether the media element is still playing using the analyzer, spam the
+// GC to ensure all refs are kept.
+const buf = new Float32Array(analyzer.frequencyBinCount);
+const startTime = Date.now();
+function checkNonSilent() {
+  analyzer.getFloatFrequencyData(buf);
+  forceGC();
+  // Wait a good 20 seconds.
+  if (Date.now() - startTime < 2000) {
+    requestAnimationFrame(checkNonSilent);
+  } else {
+    ok(true, "All objects were kept alive.");
+    SimpleTest.finish();
+  }
+}
+checkNonSilent();
+}
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_MediaSource_disabled.html b/dom/media/mediasource/test/test_MediaSource_disabled.html
new file mode 100644
index 0000000000..e14f493e0f
--- /dev/null
+++ b/dom/media/mediasource/test/test_MediaSource_disabled.html
@@ -0,0 +1,31 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: disabling via pref</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+function test() {
+  ok(!window.MediaSource && !window.SourceBuffer && !window.SourceBufferList,
+     "MediaSource should be hidden behind a pref");
+  SimpleTest.doesThrow(() => new MediaSource,
+                       "MediaSource should be hidden behind a pref");
+  SimpleTest.finish();
+}
+
+SpecialPowers.pushPrefEnv({"set":
+    [
+      ["media.mediasource.enabled", false],
+    ],
+}, test);
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_MediaSource_flac_mp4.html b/dom/media/mediasource/test/test_MediaSource_flac_mp4.html
new file mode 100644
index 0000000000..9cc159e467
--- /dev/null
+++ b/dom/media/mediasource/test/test_MediaSource_flac_mp4.html
@@ -0,0 +1,33 @@
+<!DOCTYPE html>
+<html><head>
+<meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: Can seek to last frame</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test"><script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  is(ms.readyState, "open", "MediaSource must be in open state after sourceopen");
+  const sb = ms.addSourceBuffer("audio/mp4; codecs=\"flac\"");
+  ok(sb, "Create a SourceBuffer");
+
+  await fetchAndLoad(sb, "flac/IS", [""], ".mp4");
+  await fetchAndLoad(sb, "flac/0000", range(1, 3), ".m4s");
+  el.play();
+  ms.endOfStream();
+  await once(el, "ended");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_MediaSource_memory_reporting.html b/dom/media/mediasource/test/test_MediaSource_memory_reporting.html
new file mode 100644
index 0000000000..70c720effd
--- /dev/null
+++ b/dom/media/mediasource/test/test_MediaSource_memory_reporting.html
@@ -0,0 +1,47 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: memory reporting</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  // Load a webm video and play it.
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+  await fetchAndLoad(sb, "seek", [""], ".webm");
+  const p = once(v, "ended");
+  ms.endOfStream();
+  v.play();
+  await p;
+
+  // Test that memory reporting works once we've played a video.
+  // Grab a memory report.
+  const mgr = SpecialPowers.Cc["@mozilla.org/memory-reporter-manager;1"]
+      .getService(SpecialPowers.Ci.nsIMemoryReporterManager);
+
+  let amount;
+  const handleReport = (aProcess, aPath, aKind, aUnits, aAmount) => {
+    if (aPath == "explicit/media/resources") {
+      amount = (amount || 0) + aAmount;
+    }
+  };
+
+  await new Promise(r => mgr.getReports(handleReport, null, r, null, /* anonymized = */ false));
+  ok(true, "Yay didn't crash!");
+  ok(amount !== undefined, "Got media resources amount");
+  ok(amount > 0, "Non-zero amount reported for media resources");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_MediaSource_mp4.html b/dom/media/mediasource/test/test_MediaSource_mp4.html
new file mode 100644
index 0000000000..2ab79f37f3
--- /dev/null
+++ b/dom/media/mediasource/test/test_MediaSource_mp4.html
@@ -0,0 +1,90 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: basic functionality</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  SimpleTest.doesThrow(() => new SourceBuffer, "new SourceBuffer should fail");
+  SimpleTest.doesThrow(() => new SourceBufferList, "new SourceBufferList direct should fail");
+
+  ok(ms instanceof EventTarget, "MediaSource must be an EventTarget");
+  is(ms.readyState, "closed", "New MediaSource must be in closed state");
+
+  // Wrapper creation, tests for leaks.
+  SpecialPowers.wrap(ms);
+
+  // Set an expando to force wrapper creation, tests for leaks.
+  ms.foo = null;
+
+  ok(URL.createObjectURL(ms), "Create an objectURL from the MediaSource");
+
+  let loadedmetadataCount = 0;
+  let updatestartCount = 0;
+  let updateendCount = 0;
+  let updateCount = 0;
+
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  is(ms.readyState, "open", "MediaSource must be in open state after sourceopen");
+  const sb = ms.addSourceBuffer("video/mp4");
+  ok(sb, "Create a SourceBuffer");
+  is(ms.sourceBuffers.length, 1, "MediaSource.sourceBuffers is expected length");
+  is(ms.sourceBuffers[0], sb, "SourceBuffer in list matches our SourceBuffer");
+  is(ms.activeSourceBuffers.length, 0, "MediaSource.activeSourceBuffers is expected length");
+
+  sb.appendBuffer(new Uint8Array(await fetchWithXHR("bipbop/bipbop2s.mp4")));
+  is(sb.updating, true, "SourceBuffer.updating is expected value after appendBuffer");
+
+  sb.addEventListener("update", () => {
+    is(sb.updating, false, "SourceBuffer.updating is expected value in update event");
+    updateCount++;
+    /* Ensure that we endOfStream on the first update event only as endOfStream can
+       raise more if the duration of the last buffered range and the intial duration
+       differ. See bug 1065207 */
+    if (updateCount == 1) {
+      ms.endOfStream();
+    }
+  });
+
+  sb.addEventListener("updatestart", () => updatestartCount++);
+
+  sb.addEventListener("updateend", () => {
+    is(ms.activeSourceBuffers[0], sb, "SourceBuffer in active list matches our SourceBuffer");
+    is(sb.updating, false, "SourceBuffer.updating is expected value in updateend event");
+    updateendCount++;
+    v.play();
+  });
+
+  ms.addEventListener("sourceended", () => {
+    ok(true, "Receive a sourceended event");
+    is(ms.readyState, "ended", "MediaSource must be in ended state after sourceended");
+  });
+
+  v.addEventListener("loadedmetadata", () => loadedmetadataCount++);
+
+  await once(v, "ended");
+  // The bipbop video doesn't start at 0. The old MSE code adjust the
+  // timestamps and ignore the audio track. The new one doesn't.
+  isfuzzy(v.duration, 1.696, 0.166, "Video has correct duration");
+  isfuzzy(v.currentTime, 1.696, 0.166, "Video has correct duration");
+  // XXX: 2 update events can be received dueto duration differences, see bug 1065207.
+  ok(updateCount == 1 || updateCount == 2, "update event received");
+  ok(updateendCount == 1 || updateendCount == 2, "updateend event received");
+  ok(updatestartCount == 1 || updatestartCount == 2, "updatestart event received");
+  is(loadedmetadataCount, 1, "loadedmetadata event received");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_MultipleInitSegments.html b/dom/media/mediasource/test/test_MultipleInitSegments.html
new file mode 100644
index 0000000000..f4c91c08c5
--- /dev/null
+++ b/dom/media/mediasource/test/test_MultipleInitSegments.html
@@ -0,0 +1,49 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: Append buffer with multiple init segments</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+  const seek_lowres = await fetchWithXHR("seek_lowres.webm");
+  const seek = await fetchWithXHR("seek.webm");
+  const data = [
+    [seek_lowres, 0, 438],     // lowres init segment
+    [seek_lowres, 438, 25950], // lowres media segment 0-1
+    [seek, 0, 318],            // init segment
+    [seek, 46712, 67833],       // media segment 0.8-1.201
+  ];
+  const length = data.map(d => d[2] - d[1]).reduce((a, b) => a + b, 0);
+  const arrayBuffer = new Uint8Array(length);
+  let pos = 0;
+  for (const d of data) {
+    const buffer = new Uint8Array(d[0], d[1], d[2] - d[1]);
+    arrayBuffer.set(buffer, pos);
+    pos += buffer.byteLength;
+  }
+  await loadSegment(sb, arrayBuffer);
+  // Since we are passing multiple segments in one buffer,
+  // the first durationchange event from parsing the init
+  // segment will be fired before updateend.
+  const p = once(v, "durationchange");
+  ms.endOfStream();
+  await p;
+  ok(v.duration, 1.201);
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_MultipleInitSegments_mp4.html b/dom/media/mediasource/test/test_MultipleInitSegments_mp4.html
new file mode 100644
index 0000000000..47c115677d
--- /dev/null
+++ b/dom/media/mediasource/test/test_MultipleInitSegments_mp4.html
@@ -0,0 +1,44 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: Append buffer with multiple init segments</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/mp4");
+  const init = new Uint8Array(await fetchWithXHR("bipbop/bipbop_videoinit.mp4"));
+  const segment1 = new Uint8Array(await fetchWithXHR("bipbop/bipbop_video1.m4s"));
+  const segment2 = new Uint8Array(await fetchWithXHR("bipbop/bipbop_video2.m4s"));
+  const data = [init, segment1, init, segment2];
+  const length = data.map(d => d.byteLength).reduce((a, b) => a + b, 0);
+  const arrayBuffer = new Uint8Array(length);
+  let pos = 0;
+  for (const buffer of data) {
+    arrayBuffer.set(buffer, pos);
+    pos += buffer.byteLength;
+  }
+  await loadSegment(sb, arrayBuffer);
+  // Since we are passing multiple segments in one buffer,
+  // the first durationchange event from parsing the init
+  // segment will be fired before updateend.
+  const p = once(v, "durationchange");
+  ms.endOfStream();
+  await p;
+  ok(v.duration, 1.601666);
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_OnEvents.html b/dom/media/mediasource/test/test_OnEvents.html
new file mode 100644
index 0000000000..ae0f348ebe
--- /dev/null
+++ b/dom/media/mediasource/test/test_OnEvents.html
@@ -0,0 +1,42 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: live seekable range</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  const receiveEvent = e => v["got" + e] = true;
+
+  const msevents = ["onsourceopen", "onsourceended"];
+  msevents.forEach(e => ms[e] = () => receiveEvent(e));
+
+  const sblistevents = ["onaddsourcebuffer", "onremovesourcebuffer"];
+  sblistevents.forEach(e => ms.sourceBuffers[e] = () => receiveEvent(e));
+
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+
+  const sbevents = ["onupdatestart", "onupdate", "onupdateend", "onabort"];
+  sbevents.forEach(e => sb[e] = () => receiveEvent(e));
+
+  await fetchAndLoad(sb, "seek", [""], ".webm");
+  sb.appendBuffer(await fetchWithXHR("seek.webm"));
+  ms.removeSourceBuffer(sb); // will fire abort and removesourcebuffer
+  ms.endOfStream(); // will fire sourceended
+  await once(ms, "sourceended");
+  [...msevents, ...sbevents, ...sblistevents].forEach(e => ok(v["got" + e], "got " + e));
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_PlayEvents.html b/dom/media/mediasource/test/test_PlayEvents.html
new file mode 100644
index 0000000000..82ccaa42b5
--- /dev/null
+++ b/dom/media/mediasource/test/test_PlayEvents.html
@@ -0,0 +1,115 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: basic functionality</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+// This test checks that readyState is properly set and the appropriate events are being fired accordingly:
+// 1. Load 1.6s of data and ensure that canplay event is fired.
+// 2. Load data to have a complete buffered range from 0 to duration and ensure that canplaythrough is fired.
+// 3. Seek to an area with no buffered data, and ensure that readyState goes back to HAVE_METADATA
+// 4. Load 1.6s of data at the seek position and ensure that canplay is fired and that readyState is now HAVE_FUTURE_DATA
+// 5. Start playing video and check that once it reaches a position with no data, readyState goes back to HAVE_CURRENT_DATA and waiting event is fired.
+// 6. Add 1.6s of data once video element fired waiting, that canplay is fired once readyState is HAVE_FUTURE_DATA.
+// 7. Finally load data to the end and ensure that canplaythrough is fired and that readyState is now HAVE_ENOUGH_DATA
+
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  await once(ms, "sourceopen");
+  logEvents(el);
+  ok(true, "Receive a sourceopen event");
+  const videosb = ms.addSourceBuffer("video/mp4");
+  el.addEventListener("error", e => {
+    ok(false, `should not fire ${e.type} event`);
+    SimpleTest.finish();
+  });
+  is(el.readyState, el.HAVE_NOTHING, "readyState is HAVE_NOTHING");
+  let p = once(el, "loadedmetadata");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", ["init"], ".mp4");
+  await p;
+  ok(true, "got loadedmetadata event");
+  p = Promise.all([once(el, "loadeddata"), once(el, "canplay")]);
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(1, 3), ".m4s");
+  await p;
+  ok(true, "got canplay event");
+  // set element duration to 3.203333s. We do so in order to guarantee that
+  // the end of the buffered range will be equal to duration, causing
+  // canplaythrough to be fired later.
+  ms.duration = 3.203333;
+  await once(el, "durationchange");
+  ok(true, "got durationchange event");
+  // Load [0.801666, 3.203333]
+  p = once(el, "canplaythrough");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(3, 5), ".m4s");
+  await p;
+  ok(true, "got canplaythrough event");
+  // set element duration to 9.203333s, this value is set to coincide with
+  // data added later (we now have an empty range from 6s to 9.203333s).
+  ms.duration = 9.203333;
+  await once(el, "durationchange");
+  ok(true, "got durationchange event");
+  // An arbitrary value, so we are guaranteed to be in a range with no data.
+  el.currentTime = 6;
+  videosb.timestampOffset = 6;
+  ok(el.seeking, "seeking started");
+  await once(el, "seeking");
+  ok(true, "got seeking event");
+  is(el.readyState, el.HAVE_METADATA, "readyState is HAVE_METADATA");
+  // Load [6+0, 6+1.601666)
+  p = Promise.all([once(el, "seeked"), once(el, "canplay")]);
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(1, 3), ".m4s");
+  await p;
+  ok(true, "got seeked and canplay event");
+  is(el.currentTime, 6, "seeked to 6s");
+  is(el.readyState, el.HAVE_FUTURE_DATA, "readyState is HAVE_FUTURE_DATA");
+  // Load [6+1.60166, 6+3.203333]
+  p = once(el, "canplaythrough");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(3, 5), ".m4s");
+  await p;
+  ok(true, "got canplaythrough event");
+  // set element duration to 19.805s, this value is set to coincide with
+  // data added later (we now have an empty range from 15 to 19.805).
+  ms.duration = 19.805;
+  await once(el, "durationchange");
+  ok(true, "got durationchange event");
+  el.currentTime = 15;
+  videosb.timestampOffset = 15;
+  ok(el.seeking, "seeking started");
+  await once(el, "seeking");
+  ok(true, "got seeking event");
+  // Load [15+0, 15+1.601666)
+  p = once(el, "seeked");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(1, 3), ".m4s");
+  await p;
+  ok(true, "got seeked event");
+  // Load [15+1.60166, 15+3.203333]
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(3, 5), ".m4s");
+  ok(true, "data loaded");
+  // Playback we play for a little while then stall.
+  p = Promise.all([once(el, "playing"), once(el, "waiting")]);
+  el.play();
+  await p;
+  ok(true, "got playing and waiting event");
+  // Playback has stalled, readyState is back to HAVE_CURRENT_DATA.
+  is(el.readyState, el.HAVE_CURRENT_DATA, "readyState is HAVE_CURRENT_DATA");
+  // Load [15+3.203333, 15+4.805)
+  // Our final buffered range will now be [0, 3.203333)[6, 9.203333)[15, 19.805)
+  p = Promise.all([once(el, "playing"), once(el, "canplay"), once(el, "canplaythrough")]);
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(5, 7), ".m4s");
+  await p;
+  ok(true, "got playing, canplay and canplaythrough event");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_PlayEventsAutoPlaying.html b/dom/media/mediasource/test/test_PlayEventsAutoPlaying.html
new file mode 100644
index 0000000000..3e395c799d
--- /dev/null
+++ b/dom/media/mediasource/test/test_PlayEventsAutoPlaying.html
@@ -0,0 +1,58 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: basic functionality</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+// This test checks that readyState is properly set and the appropriate events are being fired accordingly:
+// 1. Ensure that play/playing aren't fired before any media data been added.
+// 2. Load 1.6s of data and ensure that canplay, play and playing events are fired.
+
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  el.autoplay = true;
+  const eventCounts = { play: 0, playing: 0 };
+  await once(ms, "sourceopen");
+  logEvents(el);
+  ok(true, "Receive a sourceopen event");
+
+  const forbiddenEvents = e => {
+    ok(el.readyState >= el.HAVE_FUTURE_DATA, "Must not have received event too early");
+    is(eventCounts[e.type], 0, "event should have only be fired once");
+    eventCounts[e.type]++;
+  };
+  el.addEventListener("play", forbiddenEvents);
+  el.addEventListener("playing", forbiddenEvents);
+
+  const videosb = ms.addSourceBuffer("video/mp4");
+  el.addEventListener("error", e => {
+    ok(false, `should not fire ${e.type} event`);
+    SimpleTest.finish();
+  });
+  is(el.readyState, el.HAVE_NOTHING, "readyState is HAVE_NOTHING");
+  let p = once(el, "loadedmetadata");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", ["init"], ".mp4");
+  await p;
+  ok(true, "got loadedmetadata event");
+  // We're only adding 1.6s worth of data, not enough for readyState to change to HAVE_ENOUGH_DATA
+  // So we end the media source so that all the playable data is available.
+  p = Promise.all(["loadeddata", "canplay", "play", "playing", "ended"].map(e => once(el, e)));
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(1, 3), ".m4s");
+  ms.endOfStream();
+  await p;
+  ok(true, "got all required event");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_PlayEventsAutoPlaying2.html b/dom/media/mediasource/test/test_PlayEventsAutoPlaying2.html
new file mode 100644
index 0000000000..8845a26ac4
--- /dev/null
+++ b/dom/media/mediasource/test/test_PlayEventsAutoPlaying2.html
@@ -0,0 +1,58 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: basic functionality</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+// This test checks that readyState is properly set and the appropriate events are being fired accordingly:
+// 1. Ensure that play/playing aren't fired before any media data been added.
+// 2. Load more than 10s of data and ensure that canplay, play and playing events are fired.
+
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  el.autoplay = true;
+  const eventCounts = { play: 0, playing: 0 };
+  await once(ms, "sourceopen");
+  logEvents(el);
+  ok(true, "Receive a sourceopen event");
+
+  const forbiddenEvents = e => {
+    ok(el.readyState >= el.HAVE_FUTURE_DATA, "Must not have received event too early");
+    is(eventCounts[e.type], 0, "event should have only be fired once");
+    eventCounts[e.type]++;
+  };
+  el.addEventListener("play", forbiddenEvents);
+  el.addEventListener("playing", forbiddenEvents);
+
+  const videosb = ms.addSourceBuffer("video/mp4");
+  el.addEventListener("error", e => {
+    ok(false, `should not fire ${e.type} event`);
+    SimpleTest.finish();
+  });
+  is(el.readyState, el.HAVE_NOTHING, "readyState is HAVE_NOTHING");
+  let p = once(el, "loadedmetadata");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", ["init"], ".mp4");
+  await p;
+  ok(true, "got loadedmetadata event");
+  // We shift the timestamps slightly to create a small gaps at the start.
+  // one that should normally be ignored.
+  videosb.timestampOffset = 0.1;
+  p = Promise.all(["loadeddata", "canplay", "play", "playing"].map(e => once(el, e)));
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(1, 14), ".m4s");
+  await p;
+  ok(true, "got all required event");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_RemoveSourceBuffer.html b/dom/media/mediasource/test/test_RemoveSourceBuffer.html
new file mode 100644
index 0000000000..11c6a51deb
--- /dev/null
+++ b/dom/media/mediasource/test/test_RemoveSourceBuffer.html
@@ -0,0 +1,52 @@
+<!DOCTYPE html>
+<html><head>
+<meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: check buffered status after removed all source buffer</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test"><script class="testbody" type="text/javascript">
+
+const videoURL = "seek.webm";
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async function(ms, el) {
+  info("- wait for sourceopen -");
+  await once(ms, "sourceopen");
+
+  info("- wait for fetching data -");
+  const arrayBuffer = await fetchWithXHR(videoURL);
+
+  info("- create source buffer and append data -");
+  const sourceBuffer = ms.addSourceBuffer("video/webm");
+  sourceBuffer.appendBuffer(arrayBuffer);
+  await once(sourceBuffer, "updateend");
+  is(ms.sourceBuffers.length, 1,
+     "the length of source buffers list is 1.");
+  is(ms.activeSourceBuffers.length, 1,
+     "the length of active source buffers list is 1.");
+  ok(ms.duration != 0, "duration is not 0.");
+  is(el.buffered.length, 1, "buffered range is 1.");
+
+  info("- remove source buffer from media source -");
+  ms.removeSourceBuffer(sourceBuffer);
+  await once(ms.sourceBuffers, "removesourcebuffer");
+  is(ms.sourceBuffers.length, 0, "source buffers list is empty.");
+  is(ms.activeSourceBuffers.length, 0, "active source buffers list is empty.");
+  ok(ms.duration != 0, "duration is not 0.");
+  is(el.buffered.length, 0,
+     "buffered range is empty since we don't have any source buffer.");
+
+  info("- call endOfStream -");
+  ms.endOfStream();
+  is(ms.duration, 0, "duraton is 0 since we don't have any source buffer.");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_Resolution_change_should_not_cause_video_freeze.html b/dom/media/mediasource/test/test_Resolution_change_should_not_cause_video_freeze.html
new file mode 100644
index 0000000000..640b53441e
--- /dev/null
+++ b/dom/media/mediasource/test/test_Resolution_change_should_not_cause_video_freeze.html
@@ -0,0 +1,49 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: video resolution changes during playback should not cause video freeze (Bug 1718709)</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer('video/mp4');
+  sb.appendBuffer(new Uint8Array(await fetchWithXHR("bug1718709_low_res.mp4")));
+  ok(true, "appended low resolution video");
+  sb.appendBuffer(new Uint8Array(await fetchWithXHR("bug1718709_high_res.mp4")));
+  ok(true, "appended high resolution video");
+
+  info(`start from the position which is near to the place where resolution changes`);
+  v.currentTime = 13;
+  ok(await v.play().then(_=>true,_=>false), "video started playing");
+
+  // When video resolution changes, it should not cause video freeze so we check
+  // its painted frame amount regularly to see if we stop updating video frames.
+  let lastPaintedFramesAmount = v.mozPaintedFrames;
+  const intervalHandle = setInterval(_=>{
+    ok(lastPaintedFramesAmount < v.mozPaintedFrames,
+       `painted frames keeps growing from ${lastPaintedFramesAmount} to ${v.mozPaintedFrames}`);
+    lastPaintedFramesAmount = v.mozPaintedFrames;
+  }, 1000);
+
+  // As we didn't append full video, so we will receive `waiting` event later
+  // which indicates that we can stop testing because we've finished playing
+  // the high resolution part.
+  await new Promise(r => {
+    v.onwaiting = _ => {
+      clearInterval(intervalHandle);
+      r();
+    }
+  });
+  SimpleTest.finish();
+});
+
+</script>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_ResumeAfterClearing_mp4.html b/dom/media/mediasource/test/test_ResumeAfterClearing_mp4.html
new file mode 100644
index 0000000000..40e512ba12
--- /dev/null
+++ b/dom/media/mediasource/test/test_ResumeAfterClearing_mp4.html
@@ -0,0 +1,44 @@
+<!DOCTYPE html>
+<html><head>
+<meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: Don't get stuck buffering for too long when we have frames to show</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test"><script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  ms.addEventListener("sourceopen", () => ok(false, "No more sourceopen"));
+  const sb = ms.addSourceBuffer("video/mp4");
+  ok(sb, "Create a SourceBuffer");
+  sb.addEventListener("error", e => {
+    ok(false, "Got Error: " + e);
+    SimpleTest.finish();
+  });
+  await fetchAndLoad(sb, "bipbop/bipbop", ["init"], ".mp4");
+  let p = once(v, "loadeddata");
+  await fetchAndLoad(sb, "bipbop/bipbop", range(1, 3), ".m4s");
+  await p;
+  // clear the entire sourcebuffer.
+  sb.remove(0, 5);
+  await once(sb, "updateend");
+  v.play();
+  // We have nothing to play, waiting will be fired.
+  await once(v, "waiting");
+  p = once(v, "playing");
+  await fetchAndLoad(sb, "bipbop/bipbop", range(1, 4), ".m4s");
+  await p;
+  ms.endOfStream();
+  await Promise.all([once(ms, "sourceended"), once(v, "ended")]);
+  SimpleTest.finish(SimpleTest);
+});
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_SeekNoData_mp4.html b/dom/media/mediasource/test/test_SeekNoData_mp4.html
new file mode 100644
index 0000000000..1ea64f3fa4
--- /dev/null
+++ b/dom/media/mediasource/test/test_SeekNoData_mp4.html
@@ -0,0 +1,57 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: basic functionality</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  const audiosb = ms.addSourceBuffer("audio/mp4");
+  const videosb = ms.addSourceBuffer("video/mp4");
+  el.addEventListener("error", e => {
+    ok(false, `should not fire ${e.type} event`);
+    SimpleTest.finish();
+  });
+  is(el.readyState, el.HAVE_NOTHING, "readyState is HAVE_NOTHING");
+  must_not_throw(() => el.currentTime = 3, "setting currentTime is valid");
+  is(el.currentTime, 3, "currentTime is default playback start position");
+  is(el.seeking, false, "seek not started with HAVE_NOTHING");
+  await Promise.all([
+    fetchAndLoad(audiosb, "bipbop/bipbop_audio", ["init"], ".mp4"),
+    fetchAndLoad(videosb, "bipbop/bipbop_video", ["init"], ".mp4"),
+    once(el, "loadedmetadata"),
+  ]);
+  const p = once(el, "seeking");
+  el.play();
+  el.currentTime = 5;
+  is(el.readyState, el.HAVE_METADATA, "readyState is HAVE_METADATA");
+  is(el.seeking, true, "seek not started with HAVE_METADATA");
+  is(el.currentTime, 5, "currentTime is seek position");
+  await p;
+  ok(true, "Got seeking event");
+  await Promise.all([
+    once(el, "seeked"),
+    fetchAndLoad(audiosb, "bipbop/bipbop_audio", range(5, 9), ".m4s"),
+    fetchAndLoad(videosb, "bipbop/bipbop_video", range(6, 10), ".m4s"),
+  ]);
+  ok(true, "Got seeked event");
+  ok(el.currentTime >= 5, "Time >= 5");
+  ms.endOfStream();
+  await once(el, "ended");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_SeekToEnd_mp4.html b/dom/media/mediasource/test/test_SeekToEnd_mp4.html
new file mode 100644
index 0000000000..0405cb875f
--- /dev/null
+++ b/dom/media/mediasource/test/test_SeekToEnd_mp4.html
@@ -0,0 +1,54 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: seeking to end of data with data gap.</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, el) => {
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  const videosb = ms.addSourceBuffer("video/mp4");
+  const audiosb = ms.addSourceBuffer("audio/mp4");
+
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", ["init"], ".mp4");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(1, 6), ".m4s");
+  await fetchAndLoad(audiosb, "bipbop/bipbop_audio", ["init"], ".mp4");
+  is(videosb.buffered.length, 1, "continuous buffered range");
+  // Ensure we have at least 2s less audio than video.
+  audiosb.appendWindowEnd = videosb.buffered.end(0) - 2;
+  await fetchAndLoad(audiosb, "bipbop/bipbop_audio", range(1, 6), ".m4s");
+  ms.endOfStream();
+  await Promise.all([once(el, "durationchange"), once(ms, "sourceended")]);
+  ok(true, "endOfStream completed");
+  // Seek to the middle of the gap where audio is missing. As we are in readyState = ended
+  // seeking must complete.
+  el.currentTime = videosb.buffered.end(0) / 2 + audiosb.buffered.end(0) / 2;
+  ok(el.currentTime - audiosb.buffered.end(0) >= 1, "gap is big enough");
+  is(el.buffered.length, 1, "continuous buffered range");
+  is(el.buffered.end(0), videosb.buffered.end(0),
+     "buffered range end is aligned with longest track");
+  ok(el.seeking, "element is now seeking");
+  ok(el.currentTime >= el.buffered.start(0) && el.currentTime <= el.buffered.end(0),
+     "seeking time is in buffered range");
+  ok(el.currentTime > audiosb.buffered.end(0),
+     "seeking point is not buffered in audio track");
+  await once(el, "seeked");
+  ok(true, "we have successfully seeked");
+  // Now ensure that we can play to the end, even though we are missing data in one track.
+  el.play();
+  await once(el, "ended");
+  SimpleTest.finish(SimpleTest);
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_SeekToLastFrame_mp4.html b/dom/media/mediasource/test/test_SeekToLastFrame_mp4.html
new file mode 100644
index 0000000000..edbfdff0a0
--- /dev/null
+++ b/dom/media/mediasource/test/test_SeekToLastFrame_mp4.html
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html><head>
+<meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: Can seek to last frame</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test"><script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  const sb = ms.addSourceBuffer("video/mp4");
+  await fetchAndLoad(sb, "bipbop/bipbop_480_624kbps-video", ["init"], ".mp4");
+  await fetchAndLoad(sb, "bipbop/bipbop_480_624kbps-video", range(1, 3), ".m4s");
+  el.play();
+  // let seek to the last audio frame.
+  el.currentTime = 1.532517;
+  await once(el, "seeked");
+  ok(true, "seek completed");
+  ms.endOfStream();
+  await once(el, "ended");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_SeekTwice_mp4.html b/dom/media/mediasource/test/test_SeekTwice_mp4.html
new file mode 100644
index 0000000000..50ff32b1cd
--- /dev/null
+++ b/dom/media/mediasource/test/test_SeekTwice_mp4.html
@@ -0,0 +1,45 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: basic functionality</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  const audiosb = ms.addSourceBuffer("audio/mp4");
+  const videosb = ms.addSourceBuffer("video/mp4");
+  await fetchAndLoad(audiosb, "bipbop/bipbop_audio", ["init"], ".mp4");
+  await fetchAndLoad(audiosb, "bipbop/bipbop_audio", range(1, 5), ".m4s");
+  await fetchAndLoad(audiosb, "bipbop/bipbop_audio", range(6, 12), ".m4s");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", ["init"], ".mp4");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(1, 6), ".m4s");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(7, 14), ".m4s");
+  let p = once(el, "seeking");
+  el.play();
+  el.currentTime = 4.5; // Seek to a gap in the video
+  await p;
+  ok(true, "Got seeking event");
+  p = once(el, "seeked");
+  el.currentTime = 6; // Seek past the gap.
+  await p;
+  ok(true, "Got seeked event");
+  ok(el.currentTime >= 6, "Time >= 6");
+  ms.endOfStream();
+  await once(el, "ended");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_SeekableBeforeAndAfterEndOfStream.html b/dom/media/mediasource/test/test_SeekableBeforeAndAfterEndOfStream.html
new file mode 100644
index 0000000000..c65a4aff7e
--- /dev/null
+++ b/dom/media/mediasource/test/test_SeekableBeforeAndAfterEndOfStream.html
@@ -0,0 +1,54 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: seekable attribute after end of stream</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+
+  const arrayBuffer = await fetchWithXHR("seek.webm");
+  info("- append first buffer -");
+  sb.appendBuffer(new Uint8Array(arrayBuffer));
+
+  info("- wait for metadata -");
+  await once(v, "loadedmetadata");
+
+  info("- wait for updateend -");
+  await once(sb, "updateend");
+
+  info("- check seekable -");
+  const target = 2;
+  ok(v.seekable.length, "Resource is seekable");
+  is(v.seekable.start(0), 0, "Seekable's start point is correct");
+  is(v.seekable.end(0), ms.duration, "Seekable's end point is correct");
+  ok(v.seekable.length &&
+     target >= v.seekable.start(0) &&
+     target < v.seekable.end(0), "Target is within seekable range");
+
+  info("- call end of stream -");
+  ms.endOfStream();
+  await once(ms, "sourceended");
+
+  info("- check seekable -");
+  ok(v.seekable.length, "Resource is seekable");
+  is(v.seekable.start(0), 0, "Seekable's start point is correct");
+  is(v.seekable.end(0), ms.duration, "Seekable's end point is correct");
+  ok(v.seekable.length &&
+     target >= v.seekable.start(0) &&
+     target < v.seekable.end(0), "Target is within seekable range");
+  SimpleTest.finish();
+});
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_SeekableBeforeAndAfterEndOfStreamSplit.html b/dom/media/mediasource/test/test_SeekableBeforeAndAfterEndOfStreamSplit.html
new file mode 100644
index 0000000000..bed2af8d48
--- /dev/null
+++ b/dom/media/mediasource/test/test_SeekableBeforeAndAfterEndOfStreamSplit.html
@@ -0,0 +1,60 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: seekable attribute after end of stream with split appendBuffer</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+
+  const arrayBuffer = await fetchWithXHR("seek.webm");
+  info("- append first buffer -");
+  // 25523 is the offset of the first media segment's end
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 0, 25523));
+
+  info("- wait for metadata -");
+  await once(v, "loadedmetadata");
+
+  info("- wait for updateend -");
+  await once(sb, "updateend");
+
+  info("- append second buffer -");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 25523));
+  await once(sb, "updateend");
+
+  info("- check seekable -");
+  const target = 2;
+  ok(v.seekable.length, "Resource is seekable");
+  is(v.seekable.start(0), 0, "Seekable's start point is correct");
+  is(v.seekable.end(0), ms.duration, "Seekable's end point is correct");
+  ok(v.seekable.length &&
+     target >= v.seekable.start(0) &&
+     target < v.seekable.end(0), "Target is within seekable range");
+
+  info("- call end of stream -");
+  ms.endOfStream();
+  await once(ms, "sourceended");
+
+  info("- check seekable -");
+  ok(v.seekable.length, "Resource is seekable");
+  is(v.seekable.start(0), 0, "Seekable's start point is correct");
+  is(v.seekable.end(0), ms.duration, "Seekable's end point is correct");
+  ok(v.seekable.length &&
+     target >= v.seekable.start(0) &&
+     target < v.seekable.end(0), "Target is within seekable range");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_SeekableBeforeAndAfterEndOfStreamSplit_mp4.html b/dom/media/mediasource/test/test_SeekableBeforeAndAfterEndOfStreamSplit_mp4.html
new file mode 100644
index 0000000000..00b5f9a832
--- /dev/null
+++ b/dom/media/mediasource/test/test_SeekableBeforeAndAfterEndOfStreamSplit_mp4.html
@@ -0,0 +1,60 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: seekable attribute after end of stream with split appendBuffer</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/mp4");
+
+  const arrayBuffer = await fetchWithXHR("bipbop/bipbop2s.mp4");
+  info("- append first buffer -");
+  // 25819 is the offset of the first media segment's end
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 0, 25819));
+
+  info("- wait for metadata -");
+  await once(v, "loadedmetadata");
+
+  info("- wait for updateend -");
+  await once(sb, "updateend");
+
+  info("- append second buffer -");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 25819));
+  await once(sb, "updateend");
+
+  info("- check seekable -");
+  const target = 1.3;
+  ok(v.seekable.length, "Resource is seekable");
+  is(v.seekable.start(0), 0, "Seekable's start point is correct");
+  is(v.seekable.end(0), ms.duration, "Seekable's end point is correct");
+  ok(v.seekable.length &&
+     target >= v.seekable.start(0) &&
+     target < v.seekable.end(0), "Target is within seekable range");
+
+  info("- call end of stream -");
+  ms.endOfStream();
+  await once(ms, "sourceended");
+
+  info("- check seekable -");
+  ok(v.seekable.length, "Resource is seekable");
+  is(v.seekable.start(0), 0, "Seekable's start point is correct");
+  is(v.seekable.end(0), ms.duration, "Seekable's end point is correct");
+  ok(v.seekable.length &&
+     target >= v.seekable.start(0) &&
+     target < v.seekable.end(0), "Target is within seekable range");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_SeekableBeforeAndAfterEndOfStream_mp4.html b/dom/media/mediasource/test/test_SeekableBeforeAndAfterEndOfStream_mp4.html
new file mode 100644
index 0000000000..c8e53833fb
--- /dev/null
+++ b/dom/media/mediasource/test/test_SeekableBeforeAndAfterEndOfStream_mp4.html
@@ -0,0 +1,55 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: seekable attribute after end of stream</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/mp4");
+
+  const arrayBuffer = await fetchWithXHR("bipbop/bipbop2s.mp4");
+  info("- append buffer -");
+  sb.appendBuffer(new Uint8Array(arrayBuffer));
+
+  info("- wait for metadata -");
+  await once(v, "loadedmetadata");
+
+  info("- wait for updateend -");
+  await once(sb, "updateend");
+
+  info("- check seekable -");
+  const target = 1.3;
+  ok(v.seekable.length, "Resource is seekable");
+  is(v.seekable.start(0), 0, "Seekable's start point is correct");
+  is(v.seekable.end(0), ms.duration, "Seekable's end point is correct");
+  ok(v.seekable.length &&
+     target >= v.seekable.start(0) &&
+     target < v.seekable.end(0), "Target is within seekable range");
+
+  info("- call end of stream -");
+  ms.endOfStream();
+  await once(ms, "sourceended");
+
+  info("- check seekable -");
+  ok(v.seekable.length, "Resource is seekable");
+  is(v.seekable.start(0), 0, "Seekable's start point is correct");
+  is(v.seekable.end(0), ms.duration, "Seekable's end point is correct");
+  ok(v.seekable.length &&
+     target >= v.seekable.start(0) &&
+     target < v.seekable.end(0), "Target is within seekable range");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_SeekedEvent_mp4.html b/dom/media/mediasource/test/test_SeekedEvent_mp4.html
new file mode 100644
index 0000000000..70401f1eb1
--- /dev/null
+++ b/dom/media/mediasource/test/test_SeekedEvent_mp4.html
@@ -0,0 +1,48 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: Check that seeked event is fired prior loadeddata</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  const events = ["seeked", "loadeddata", "playing"];
+  let eventCount = 0;
+  events.forEach(type => el.addEventListener(type,
+      () => is(events[eventCount++], type, "events must come in order")));
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  const videosb = ms.addSourceBuffer("video/mp4");
+  is(el.readyState, el.HAVE_NOTHING, "readyState is HAVE_NOTHING");
+  let p = once(el, "loadedmetadata");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", ["init"], ".mp4");
+  await p;
+  el.play();
+  videosb.timestampOffset = 2;
+  is(el.readyState, el.HAVE_METADATA, "readyState is HAVE_METADATA");
+  // Load [2, 3.606).
+  p = once(el, "play");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", ["1"], ".m4s");
+  await p;
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", ["2"], ".m4s");
+  // TODO: readyState should be at least HAVE_CURRENTDATA, see bug 1367993.
+  ok(el.readyState >= el.HAVE_METADATA, "readyState is HAVE_METADATA");
+  el.currentTime = 2;
+  await Promise.all([once(el, "seeked"), once(el, "playing")]);
+  ok(true, "completed seek");
+  is(eventCount, events.length, "Received expected number of events");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_Sequence_mp4.html b/dom/media/mediasource/test/test_Sequence_mp4.html
new file mode 100644
index 0000000000..2b56cb8bcc
--- /dev/null
+++ b/dom/media/mediasource/test/test_Sequence_mp4.html
@@ -0,0 +1,37 @@
+<!DOCTYPE html>
+<html><head>
+<meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: Don't get stuck buffering for too long when we have frames to show</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test"><script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  ms.addEventListener("sourceopen", () => ok(false, "No more sourceopen"));
+  const sb = ms.addSourceBuffer("video/mp4");
+  ok(sb, "Create a SourceBuffer");
+  sb.addEventListener("error", e => {
+    ok(false, "Got Error: " + e);
+    SimpleTest.finish();
+  });
+  sb.mode = "sequence";
+
+  await fetchAndLoad(sb, "bipbop/bipbop_video", ["init"], ".mp4");
+  await fetchAndLoad(sb, "bipbop/bipbop_video", ["5"], ".m4s");
+  await fetchAndLoad(sb, "bipbop/bipbop_video", ["2"], ".m4s");
+  is(v.buffered.length, 1, "Continuous buffered range");
+  is(v.buffered.start(0), 0, "Buffered range starts at 0");
+  ok(sb.timestampOffset > 0, "SourceBuffer.timestampOffset set to allow continuous range");
+  SimpleTest.finish();
+});
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_SetModeThrows.html b/dom/media/mediasource/test/test_SetModeThrows.html
new file mode 100644
index 0000000000..c715854b41
--- /dev/null
+++ b/dom/media/mediasource/test/test_SetModeThrows.html
@@ -0,0 +1,34 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: append initialization</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+// MSE supports setting mode now. make sure it does not throw.
+runWithMSE(function(ms, v) {
+  ms.addEventListener("sourceopen", () => {
+    const sb = ms.addSourceBuffer("video/webm");
+
+    sb.mode = "segments";
+    ok("true", "Setting to segments does not throw");
+    try {
+      sb.mode = "sequence";
+      ok("true", "Setting to sequence does not throw");
+    } catch (e) { ok(false, "Should not throw setting mode to sequence: " + e); }
+
+    SimpleTest.finish();
+  });
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_SplitAppend.html b/dom/media/mediasource/test/test_SplitAppend.html
new file mode 100644
index 0000000000..a4be5de282
--- /dev/null
+++ b/dom/media/mediasource/test/test_SplitAppend.html
@@ -0,0 +1,36 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: append initialization and media segment separately</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+
+  const arrayBuffer = await fetchWithXHR("seek.webm");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 0, 318));
+  v.play();
+  await once(sb, "updateend");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 318));
+  await once(sb, "updateend");
+  ms.endOfStream();
+  await once(v, "ended");
+  // XXX: Duration should be exactly 4.0, see bug 1065207.
+  ok(Math.abs(v.duration - 4) <= 0.002, "Video has correct duration");
+  ok(Math.abs(v.currentTime - 4) <= 0.002, "Video has played to end");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_SplitAppendDelay.html b/dom/media/mediasource/test/test_SplitAppendDelay.html
new file mode 100644
index 0000000000..40183c3db0
--- /dev/null
+++ b/dom/media/mediasource/test/test_SplitAppendDelay.html
@@ -0,0 +1,38 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: append segments with delay</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+SimpleTest.requestFlakyTimeout("untriaged");
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+
+  const arrayBuffer = await fetchWithXHR("seek.webm");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 0, 318));
+  v.play();
+  await once(sb, "updateend");
+  await wait(1000);
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 318));
+  await once(sb, "updateend");
+  ms.endOfStream();
+  await once(v, "ended");
+  // XXX: Duration should be exactly 4.0, see bug 1065207.
+  ok(Math.abs(v.duration - 4) <= 0.002, "Video has correct duration");
+  ok(Math.abs(v.currentTime - 4) <= 0.002, "Video has played to end");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_SplitAppendDelay_mp4.html b/dom/media/mediasource/test/test_SplitAppendDelay_mp4.html
new file mode 100644
index 0000000000..c072a526cf
--- /dev/null
+++ b/dom/media/mediasource/test/test_SplitAppendDelay_mp4.html
@@ -0,0 +1,39 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: append segments with delay</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+SimpleTest.requestFlakyTimeout("untriaged");
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/mp4");
+
+  const arrayBuffer = await fetchWithXHR("bipbop/bipbop2s.mp4");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 0, 1395));
+  v.play();
+  await once(sb, "updateend");
+  await wait(1000);
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 1395));
+  await once(sb, "updateend");
+  ms.endOfStream();
+  await once(v, "ended");
+  // The bipbop video doesn't start at 0. The old MSE code adjust the
+  // timestamps and ignore the audio track. The new one doesn't.
+  isfuzzy(v.duration, 1.696, 0.166, "Video has correct duration");
+  isfuzzy(v.currentTime, 1.696, 0.166, "Video has played to end");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_SplitAppend_mp4.html b/dom/media/mediasource/test/test_SplitAppend_mp4.html
new file mode 100644
index 0000000000..308fa9837d
--- /dev/null
+++ b/dom/media/mediasource/test/test_SplitAppend_mp4.html
@@ -0,0 +1,38 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: append initialization and media segment separately</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/mp4");
+
+  const arrayBuffer = await fetchWithXHR("bipbop/bipbop2s.mp4");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 0, 1395));
+  v.play();
+  await once(sb, "updateend");
+  sb.appendBuffer(new Uint8Array(arrayBuffer, 1395));
+  await once(sb, "updateend");
+  ms.endOfStream();
+
+  await once(v, "ended");
+  // The bipbop video doesn't start at 0. The old MSE code adjust the
+  // timestamps and ignore the audio track. The new one doesn't.
+  isfuzzy(v.duration, 1.696, 0.166, "Video has correct duration");
+  isfuzzy(v.currentTime, 1.696, 0.166, "Video has played to end");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_Threshold_mp4.html b/dom/media/mediasource/test/test_Threshold_mp4.html
new file mode 100644
index 0000000000..c46883c93d
--- /dev/null
+++ b/dom/media/mediasource/test/test_Threshold_mp4.html
@@ -0,0 +1,73 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: data gap detection</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, el) => {
+  const threshold = 0.5; // gap threshold in seconds.
+  const fuzz = 0.000001; // fuzz when comparing double.
+
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  const videosb = ms.addSourceBuffer("video/mp4");
+  const vchunks = [{start: 0, end: 3.203333}, { start: 3.203333, end: 6.406666}];
+
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", ["init"], ".mp4");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(1, 5), ".m4s");
+  // We will insert a gap of threshold
+  videosb.timestampOffset = threshold;
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(5, 9), ".m4s");
+  // HTMLMediaElement fires 'waiting' if somebody invokes |play()| before the MDSM
+  // has notified it of available data. Make sure that we get 'playing' before
+  // we starting waiting for 'waiting'.
+  info("Invoking play()");
+  let p = once(el, "playing");
+  el.play();
+  await p;
+  await once(el, "waiting");
+  // We're waiting for data after the start of the last frame.
+  // 0.033333 is the duration of the last frame.
+  ok((el.currentTime >= vchunks[1].end - 0.033333 + threshold - fuzz &&
+      el.currentTime <= vchunks[1].end + threshold + fuzz),
+     `skipped the gap properly: ${el.currentTime} ${vchunks[1].end + threshold}`);
+  is(el.buffered.length, 2, "buffered range has right length");
+  // Now we test that seeking will succeed despite the gap.
+  el.currentTime = el.buffered.end(0) + (threshold / 2);
+  await once(el, "seeked");
+  // Now we test that we don't pass the gap.
+  // Clean up our sourcebuffer by removing all data.
+  videosb.timestampOffset = 0;
+  videosb.remove(0, Infinity);
+  el.currentTime = 0;
+  el.pause();
+  await once(videosb, "updateend");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(1, 5), ".m4s");
+  // We will insert a gap of threshold + 1ms
+  videosb.timestampOffset = threshold + 1 / 1000;
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(5, 9), ".m4s");
+  info("Invoking play()");
+  p = once(el, "playing");
+  el.play();
+  await p;
+  await once(el, "waiting");
+  // We're waiting for data after the start of the last frame.
+  // 0.033333 is the duration of the last frame.
+  ok((el.currentTime >= vchunks[0].end - 0.033333 - fuzz &&
+      el.currentTime <= vchunks[0].end + fuzz),
+     `stopped at the gap properly: ${el.currentTime} ${vchunks[0].end}`);
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_TimestampOffset_mp4.html b/dom/media/mediasource/test/test_TimestampOffset_mp4.html
new file mode 100644
index 0000000000..bd08e0f36e
--- /dev/null
+++ b/dom/media/mediasource/test/test_TimestampOffset_mp4.html
@@ -0,0 +1,76 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: basic functionality</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, el) => {
+  const eps = 0.01;
+
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  const audiosb = ms.addSourceBuffer("audio/mp4");
+  const videosb = ms.addSourceBuffer("video/mp4");
+  // We divide the video into 3 chunks:
+  // chunk 0: segments 1-4
+  // chunk 1: segments 5-8
+  // chunk 2: segments 9-13
+  // We then fill the timeline so that it seamlessly plays the chunks in order 0, 2, 1.
+  const vchunks = [{start: 0, end: 3.2033},
+                    { start: 3.2033, end: 6.4066},
+                    { start: 6.4066, end: 10.01}];
+  const firstvoffset = vchunks[2].end - vchunks[2].start; // Duration of chunk 2
+  const secondvoffset = -(vchunks[1].end - vchunks[1].start); // -(Duration of chunk 1)
+
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", ["init"], ".mp4");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(1, 5), ".m4s");
+  is(videosb.buffered.length, 1, "No discontinuity");
+  isfuzzy(videosb.buffered.start(0), vchunks[0].start, eps, "Chunk start");
+  isfuzzy(videosb.buffered.end(0), vchunks[0].end, eps, "Chunk end");
+  videosb.timestampOffset = firstvoffset;
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(5, 9), ".m4s");
+  is(videosb.buffered.length, 2, "One discontinuity");
+  isfuzzy(videosb.buffered.start(0), vchunks[0].start, eps, "First Chunk start");
+  isfuzzy(videosb.buffered.end(0), vchunks[0].end, eps, "First chunk end");
+  isfuzzy(videosb.buffered.start(1), vchunks[1].start + firstvoffset, eps, "Second chunk start");
+  isfuzzy(videosb.buffered.end(1), vchunks[1].end + firstvoffset, eps, "Second chunk end");
+  videosb.timestampOffset = secondvoffset;
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(9, 14), ".m4s");
+  is(videosb.buffered.length, 1, "No discontinuity (end)");
+  isfuzzy(videosb.buffered.start(0), vchunks[0].start, eps, "Chunk start");
+  isfuzzy(videosb.buffered.end(0), vchunks[2].end, eps, "Chunk end");
+  audiosb.timestampOffset = 3;
+  await fetchAndLoad(audiosb, "bipbop/bipbop_audio", ["init"], ".mp4");
+  await fetchAndLoad(audiosb, "bipbop/bipbop_audio", range(1, 12), ".m4s");
+  is(audiosb.buffered.length, 1, "No audio discontinuity");
+  isfuzzy(audiosb.buffered.start(0), 3, eps, "Audio starts at 3");
+
+  // Trim the rest of the audio.
+  audiosb.remove(videosb.buffered.end(0), Infinity);
+  videosb.remove(videosb.buffered.end(0), Infinity);
+  if (audiosb.updating) {
+    await once(audiosb, "updateend");
+  }
+  if (videosb.updating) {
+    await once(videosb, "updateend");
+  }
+  info("waiting for play to complete");
+  el.play();
+  el.currentTime = el.buffered.start(0);
+  ms.endOfStream();
+  await Promise.all([once(el, "ended"), once(el, "seeked")]);
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_TruncatedDuration.html b/dom/media/mediasource/test/test_TruncatedDuration.html
new file mode 100644
index 0000000000..c80e40ac98
--- /dev/null
+++ b/dom/media/mediasource/test/test_TruncatedDuration.html
@@ -0,0 +1,55 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: truncating the media seeks to end of media and update buffered range</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+// This test append data to a mediasource and then seek to half the duration
+// of the video.
+// We then shorten the video to 1/3rd of its original size by modifying the
+// mediasource.duration attribute.
+// We ensure that the buffered range immediately reflect the truncation
+// and that we've seeked to the new end of the media as per W3C spec and
+// video.currentTime got updated.
+
+SimpleTest.waitForExplicitFinish();
+
+const round = n => Math.round(n * 1000) / 1000;
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+
+  sb.appendBuffer(new Uint8Array(await fetchWithXHR("seek.webm")));
+  await once(sb, "updateend");
+  v.currentTime = v.duration / 2;
+  is(v.currentTime, v.duration / 2, "current time was updated");
+  ok(v.seeking, "seeking is true");
+  await once(v, "seeked");
+  const duration = round(v.duration / 3);
+  is(sb.updating, false, "sourcebuffer isn't updating");
+  sb.remove(duration, Infinity);
+  await once(sb, "updateend");
+  ms.duration = duration;
+  // frames aren't truncated, so duration may be slightly more.
+  isfuzzy(v.duration, duration, 1 / 30, "element duration was updated");
+  sb.abort(); // this shouldn't abort updating the duration (bug 1130826).
+  ok(v.seeking, "seeking is true");
+  // test playback position was updated (bug 1130839).
+  is(v.currentTime, v.duration, "current time was updated");
+  is(sb.buffered.length, 1, "One buffered range");
+  // Truncated mediasource duration will cause the video element to seek.
+  await once(v, "seeking");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_TruncatedDuration_mp4.html b/dom/media/mediasource/test/test_TruncatedDuration_mp4.html
new file mode 100644
index 0000000000..2f37150fd3
--- /dev/null
+++ b/dom/media/mediasource/test/test_TruncatedDuration_mp4.html
@@ -0,0 +1,59 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: truncating the media seeks to end of media and update buffered range</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+// This test append data to a mediasource and then seek to half the duration
+// of the video.
+// We then shorten the video to 1/3rd of its original size.
+// We ensure that the buffered range immediately reflect the truncation
+// and that we've seeked to the new end of the media as per W3C spec and
+// video.currentTime got updated.
+
+SimpleTest.waitForExplicitFinish();
+
+const round = n => Math.round(n * 1000) / 1000;
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/mp4");
+
+  sb.appendBuffer(new Uint8Array(await fetchWithXHR("bipbop/bipbop2s.mp4")));
+  await once(sb, "updateend");
+  // mp4 metadata states 10s when we only have 1.6s worth of video.
+  sb.remove(sb.buffered.end(0), Infinity);
+  await once(sb, "updateend");
+  ms.duration = sb.buffered.end(0);
+  is(v.duration, ms.duration, "current time updated with mediasource duration");
+  v.currentTime = v.duration / 2;
+  is(v.currentTime, v.duration / 2, "current time was updated");
+  ok(v.seeking, "seeking is true");
+  await once(v, "seeked");
+  const duration = round(v.duration / 3);
+  is(sb.updating, false, "sourcebuffer isn't updating");
+  sb.remove(duration, Infinity);
+  await once(sb, "updateend");
+  ms.duration = duration;
+  // frames aren't truncated, so duration may be slightly more.
+  isfuzzy(v.duration, duration, 1 / 30, "element duration was updated");
+  sb.abort(); // this shouldn't abort updating the duration (bug 1130826).
+  ok(v.seeking, "seeking is true");
+  // test playback position was updated (bug 1130839).
+  is(v.currentTime, v.duration, "current time was updated");
+  is(sb.buffered.length, 1, "One buffered range");
+  // Truncated mediasource duration will cause the video element to seek.
+  await once(v, "seeking");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_WMFUnmatchedAudioDataTime.html b/dom/media/mediasource/test/test_WMFUnmatchedAudioDataTime.html
new file mode 100644
index 0000000000..7c03214c7b
--- /dev/null
+++ b/dom/media/mediasource/test/test_WMFUnmatchedAudioDataTime.html
@@ -0,0 +1,32 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: audio output time doesn't match the input time on WMF</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer('audio/mp4;codecs=" mp4a.40.2"');
+  sb.appendBuffer(new Uint8Array(await fetchWithXHR("wmf_mismatchedaudiotime.mp4")));
+  ok(true, "appended data");
+
+  info(`if error doesn't occur, we should be able to receive 'seeked', otherwise 'error' would be dispatched`);
+  v.currentTime = 22.05;
+  ok(await Promise.race([
+    once(v, "seeked").then(_ => true),
+    once(v, "error").then(_ => false),
+  ]), "finished seeking without any error");
+  ok(!v.error, "should not get any error");
+  SimpleTest.finish();
+});
+
+</script>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_WaitingOnMissingData.html b/dom/media/mediasource/test/test_WaitingOnMissingData.html
new file mode 100644
index 0000000000..b1ad41bb37
--- /dev/null
+++ b/dom/media/mediasource/test/test_WaitingOnMissingData.html
@@ -0,0 +1,60 @@
+<!DOCTYPE html>
+<html><head>
+<meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: |waiting| event when source data is missing</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test"><script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, el) => {
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  const sb = ms.addSourceBuffer("video/webm");
+  sb.addEventListener("error", e => {
+    ok(false, "Got Error: " + e);
+    SimpleTest.finish();
+  });
+  const arrayBuffer = await fetchWithXHR("seek.webm");
+  await loadSegment(sb, new Uint8Array(arrayBuffer, 0, 318));
+  await loadSegment(sb, new Uint8Array(arrayBuffer, 318, 25223 - 318));
+  await loadSegment(sb, new Uint8Array(arrayBuffer, 25223, 46712 - 25223));
+  /* Note - Missing |46712, 67833 - 46712| segment here */
+  await loadSegment(sb, new Uint8Array(arrayBuffer, 67833, 88966 - 67833));
+  await loadSegment(sb, new Uint8Array(arrayBuffer, 88966));
+  // HTMLMediaElement fires "waiting" if somebody invokes |play()| before the MDSM
+  // has notified it of available data. Make sure that we get "playing" before
+  // we starting waiting for "waiting".
+  info("Invoking play()");
+  let p = once(el, "playing");
+  el.play();
+  await p;
+  ok(true, "Video playing. It should play for a bit, then fire 'waiting'");
+  p = once(el, "waiting");
+  el.play();
+  await p;
+  // currentTime is based on the current video frame, so if the audio ends just before
+  // the next video frame, currentTime can be up to 1 frame's worth earlier than
+  // min(audioEnd, videoEnd).
+  // 0.0465 is the length of the last audio frame.
+  ok(el.currentTime >= (sb.buffered.end(0) - 0.0465),
+     `Got a waiting event at ${el.currentTime}`);
+  info("Loading more data");
+  p = once(el, "ended");
+  await loadSegment(sb, new Uint8Array(arrayBuffer, 46712, 67833 - 46712));
+  ms.endOfStream();
+  await p;
+  // These fuzz factors are bigger than they should be. We should investigate
+  // and fix them in bug 1137574.
+  isfuzzy(el.duration, 4.001, 0.1, "Video has correct duration: " + el.duration);
+  isfuzzy(el.currentTime, el.duration, 0.1, "Video has correct currentTime.");
+  SimpleTest.finish();
+});
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_WaitingOnMissingDataEnded_mp4.html b/dom/media/mediasource/test/test_WaitingOnMissingDataEnded_mp4.html
new file mode 100644
index 0000000000..8ca61eae7e
--- /dev/null
+++ b/dom/media/mediasource/test/test_WaitingOnMissingDataEnded_mp4.html
@@ -0,0 +1,47 @@
+<!DOCTYPE html>
+<html><head>
+<meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: |waiting| event when source data is missing</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test"><script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  el.addEventListener("ended", () => {
+    ok(false, "ended should never fire");
+    SimpleTest.finish();
+  });
+  const videosb = ms.addSourceBuffer("video/mp4");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", ["init"], ".mp4");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(1, 5), ".m4s");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(6, 8), ".m4s");
+  is(el.buffered.length, 2, "discontinuous buffered range");
+  ms.endOfStream();
+  await Promise.all([once(el, "durationchange"), once(ms, "sourceended")]);
+  // HTMLMediaElement fires "waiting" if somebody invokes |play()| before the MDSM
+  // has notified it of available data. Make sure that we get "playing" before
+  // we starting waiting for "waiting".
+  info("Invoking play()");
+  el.play();
+  await once(el, "playing");
+  ok(true, "Video playing. It should play for a bit, then fire 'waiting'");
+  await once(el, "waiting");
+  // waiting is fired when we start to play the last frame.
+  // 0.033334 is the duration of the last frame, + 0.000001 of fuzz.
+  // the next video frame, currentTime can be up to 1 frame's worth earlier than end of video.
+  isfuzzy(el.currentTime, videosb.buffered.end(0), 0.033334, "waiting was fired on gap");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_WaitingOnMissingData_mp4.html b/dom/media/mediasource/test/test_WaitingOnMissingData_mp4.html
new file mode 100644
index 0000000000..f6768754e7
--- /dev/null
+++ b/dom/media/mediasource/test/test_WaitingOnMissingData_mp4.html
@@ -0,0 +1,61 @@
+<!DOCTYPE html>
+<html><head>
+<meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: |waiting| event when source data is missing</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test"><script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  const audiosb = ms.addSourceBuffer("audio/mp4");
+  const videosb = ms.addSourceBuffer("video/mp4");
+  await fetchAndLoad(audiosb, "bipbop/bipbop_audio", ["init"], ".mp4");
+  await fetchAndLoad(audiosb, "bipbop/bipbop_audio", range(1, 5), ".m4s");
+  await fetchAndLoad(audiosb, "bipbop/bipbop_audio", range(6, 12), ".m4s");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", ["init"], ".mp4");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(1, 6), ".m4s");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(7, 14), ".m4s");
+  // HTMLMediaElement fires "waiting" if somebody invokes |play()| before the MDSM
+  // has notified it of available data. Make sure that we get "playing" before
+  // we starting waiting for "waiting".
+  info("Invoking play()");
+  let p = once(el, "playing");
+  el.play();
+  await p;
+  ok(true, "Video playing. It should play for a bit, then fire 'waiting'");
+  p = once(el, "waiting");
+  el.play();
+  await p;
+  // currentTime is based on the current video frame, so if the audio ends just before
+  // the next video frame, currentTime can be up to 1 frame's worth earlier than
+  // min(audioEnd, videoEnd).
+  // 0.0465 is the length of the last audio frame.
+  ok(el.currentTime >= (Math.min(audiosb.buffered.end(0), videosb.buffered.end(0)) - 0.0465),
+     `Got a waiting event at ${el.currentTime}`);
+  info("Loading more data");
+  p = once(el, "ended");
+  await Promise.all([
+    fetchAndLoad(audiosb, "bipbop/bipbop_audio", [5], ".m4s"),
+    fetchAndLoad(videosb, "bipbop/bipbop_video", [6], ".m4s"),
+  ]);
+  ms.endOfStream();
+  await p;
+  // These fuzz factors are bigger than they should be. We should investigate
+  // and fix them in bug 1137574.
+  isfuzzy(el.duration, 10.1, 0.1, "Video has correct duration: " + el.duration);
+  isfuzzy(el.currentTime, el.duration, 0.1, "Video has correct currentTime.");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_WaitingToEndedTransition_mp4.html b/dom/media/mediasource/test/test_WaitingToEndedTransition_mp4.html
new file mode 100644
index 0000000000..9c3fc73161
--- /dev/null
+++ b/dom/media/mediasource/test/test_WaitingToEndedTransition_mp4.html
@@ -0,0 +1,52 @@
+<!DOCTYPE html>
+<html><head>
+<meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>MSE: |waiting| event when source data is missing</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test"><script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  const audiosb = ms.addSourceBuffer("audio/mp4");
+  const videosb = ms.addSourceBuffer("video/mp4");
+  // ensure tracks end at approximately the same time to ensure ended event is
+  // always fired (bug 1233639).
+  audiosb.appendWindowEnd = 3.9;
+  videosb.appendWindowEnd = 3.9;
+  await fetchAndLoad(audiosb, "bipbop/bipbop_audio", ["init"], ".mp4");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", ["init"], ".mp4");
+  await fetchAndLoad(audiosb, "bipbop/bipbop_audio", range(1, 5), ".m4s");
+  await fetchAndLoad(videosb, "bipbop/bipbop_video", range(1, 6), ".m4s");
+  // HTMLMediaElement fires "waiting" if somebody invokes |play()| before the MDSM
+  // has notified it of available data. Make sure that we get "playing" before
+  // we starting waiting for "waiting".
+  info("Invoking play()");
+  let p = once(el, "playing");
+  el.play();
+  await p;
+  ok(true, "Video playing. It should play for a bit, then fire 'waiting'");
+  await once(el, "waiting");
+  p = once(el, "ended");
+  ms.endOfStream();
+  await p;
+  // Following bug 1524890, we now implement fully step 8 of the coded frame
+  // processing algorithm
+  // http://w3c.github.io/media-source/index.html#sourcebuffer-coded-frame-processing
+  // As such, duration is exactly the value of videosb.appendWindowEnd
+  is(el.duration, videosb.appendWindowEnd, "Video has correct duration: " + el.duration);
+  is(el.currentTime, el.duration, "Video has correct currentTime.");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_WebMTagsBeforeCluster.html b/dom/media/mediasource/test/test_WebMTagsBeforeCluster.html
new file mode 100644
index 0000000000..d1d45173cd
--- /dev/null
+++ b/dom/media/mediasource/test/test_WebMTagsBeforeCluster.html
@@ -0,0 +1,47 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: WebM tags element before cluster element</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+addMSEPrefs(["media.mediasource.webm.enabled", true]);
+
+runWithMSE(async (ms, v) => {
+  await once(ms, "sourceopen");
+  const sb = ms.addSourceBuffer("video/webm");
+
+  const arrayBuffer = await fetchWithXHR("tags_before_cluster.webm");
+  info("- append buffer -");
+  sb.appendBuffer(new Uint8Array(arrayBuffer));
+
+  info("- wait for metadata -");
+  await once(v, "loadedmetadata");
+
+  info("- wait for updateend -");
+  await once(sb, "updateend");
+
+  info("- call end of stream -");
+  ms.endOfStream();
+  await once(ms, "sourceended");
+
+  info("- check buffered range -");
+  is(sb.buffered.length, 1, "buffered range is not empty.");
+
+  info("- video is playing -");
+  v.play();
+  await once(v, "timeupdate");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/test_trackidchange_mp4.html b/dom/media/mediasource/test/test_trackidchange_mp4.html
new file mode 100644
index 0000000000..fdbeece3cd
--- /dev/null
+++ b/dom/media/mediasource/test/test_trackidchange_mp4.html
@@ -0,0 +1,32 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>MSE: test append of audio with similar init segments that have different track ids</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mediasource.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+runWithMSE(async (ms, el) => {
+  el.controls = true;
+  await once(ms, "sourceopen");
+  ok(true, "Receive a sourceopen event");
+  const audiosb = ms.addSourceBuffer("audio/mp4");
+  await fetchAndLoad(audiosb, "init-trackid2", [''], ".mp4");
+  await fetchAndLoad(audiosb, "segment-2.0001", [''], ".m4s");
+  await fetchAndLoad(audiosb, "init-trackid3", [''], ".mp4");
+  await fetchAndLoad(audiosb, "segment-3.0002", [''], ".m4s");
+  is(el.buffered.length, 1, "data is buffered");
+  is(el.buffered.end(0), 8, "all data got appended");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/media/mediasource/test/whitenoise-he-aac-5s.mp4 b/dom/media/mediasource/test/whitenoise-he-aac-5s.mp4
new file mode 100644
index 0000000000..db648b8229
--- /dev/null
+++ b/dom/media/mediasource/test/whitenoise-he-aac-5s.mp4
diff --git a/dom/media/mediasource/test/wmf_mismatchedaudiotime.mp4 b/dom/media/mediasource/test/wmf_mismatchedaudiotime.mp4
new file mode 100644
index 0000000000..9e179bd326
--- /dev/null
+++ b/dom/media/mediasource/test/wmf_mismatchedaudiotime.mp4