1 files changed, 501 insertions, 0 deletions
diff --git a/dom/media/MediaSegment.h b/dom/media/MediaSegment.h
new file mode 100644
index 0000000000..181a726c74
--- /dev/null
+++ b/dom/media/MediaSegment.h
@@ -0,0 +1,501 @@
+/* -*- 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/. */
+
+#ifndef MOZILLA_MEDIASEGMENT_H_
+#define MOZILLA_MEDIASEGMENT_H_
+
+#include "PrincipalHandle.h"
+#include "nsTArray.h"
+#ifdef MOZILLA_INTERNAL_API
+#  include "mozilla/TimeStamp.h"
+#endif
+#include <algorithm>
+
+namespace mozilla {
+
+/**
+ * Track or graph rate in Hz. Maximum 1 << TRACK_RATE_MAX_BITS Hz. This
+ * maximum avoids overflow in conversions between track rates and conversions
+ * from seconds.
+ */
+typedef int32_t TrackRate;
+const int64_t TRACK_RATE_MAX_BITS = 20;
+const TrackRate TRACK_RATE_MAX = 1 << TRACK_RATE_MAX_BITS;
+
+/**
+ * A number of ticks at a rate determined by some underlying track (e.g., audio
+ * sample rate). We want to make sure that multiplying TrackTicks by a TrackRate
+ * doesn't overflow, so we set its max accordingly.
+ * TrackTime should be used instead when we're working with MediaTrackGraph's
+ * rate, but TrackTicks can be used outside MediaTracks when we have data at a
+ * different rate.
+ */
+typedef int64_t TrackTicks;
+const int64_t TRACK_TICKS_MAX = INT64_MAX >> TRACK_RATE_MAX_BITS;
+
+/**
+ * We represent media times in 64-bit audio frame counts or ticks.
+ * All tracks in a MediaTrackGraph have the same rate.
+ */
+typedef int64_t MediaTime;
+const int64_t MEDIA_TIME_MAX = TRACK_TICKS_MAX;
+
+/**
+ * Media time relative to the start of a MediaTrack.
+ */
+typedef MediaTime TrackTime;
+const TrackTime TRACK_TIME_MAX = MEDIA_TIME_MAX;
+
+/**
+ * Media time relative to the start of the graph timeline.
+ */
+typedef MediaTime GraphTime;
+const GraphTime GRAPH_TIME_MAX = MEDIA_TIME_MAX;
+
+/* Time conversion helper functions */
+inline TrackTicks RateConvertTicksRoundDown(TrackRate aOutRate,
+                                            TrackRate aInRate,
+                                            TrackTicks aTicks) {
+  MOZ_ASSERT(0 < aOutRate && aOutRate <= TRACK_RATE_MAX, "Bad out rate");
+  MOZ_ASSERT(0 < aInRate && aInRate <= TRACK_RATE_MAX, "Bad in rate");
+  MOZ_ASSERT(0 <= aTicks && aTicks <= TRACK_TICKS_MAX, "Bad ticks");
+  return (aTicks * aOutRate) / aInRate;
+}
+
+inline TrackTicks RateConvertTicksRoundUp(TrackRate aOutRate, TrackRate aInRate,
+                                          TrackTicks aTicks) {
+  MOZ_ASSERT(0 < aOutRate && aOutRate <= TRACK_RATE_MAX, "Bad out rate");
+  MOZ_ASSERT(0 < aInRate && aInRate <= TRACK_RATE_MAX, "Bad in rate");
+  MOZ_ASSERT(0 <= aTicks && aTicks <= TRACK_TICKS_MAX, "Bad ticks");
+  return (aTicks * aOutRate + aInRate - 1) / aInRate;
+}
+
+/**
+ * The number of chunks allocated by default for a MediaSegment.
+ * Appending more chunks than this will cause further allocations.
+ *
+ * 16 is an arbitrary number intended to cover the most common cases in the
+ * MediaTrackGraph (1 with silence and 1-2 with data for a realtime track)
+ * with some margin.
+ */
+const size_t DEFAULT_SEGMENT_CAPACITY = 16;
+
+/**
+ * A MediaSegment is a chunk of media data sequential in time. Different
+ * types of data have different subclasses of MediaSegment, all inheriting
+ * from MediaSegmentBase.
+ * All MediaSegment data is timed using TrackTime. The actual tick rate
+ * is defined on a per-track basis. For some track types, this can be
+ * a fixed constant for all tracks of that type (e.g. 1MHz for video).
+ *
+ * Each media segment defines a concept of "null media data" (e.g. silence
+ * for audio or "no video frame" for video), which can be efficiently
+ * represented. This is used for padding.
+ */
+class MediaSegment {
+ public:
+  MediaSegment(const MediaSegment&) = delete;
+  MediaSegment& operator=(const MediaSegment&) = delete;
+
+  MOZ_COUNTED_DTOR_VIRTUAL(MediaSegment)
+
+  enum Type { AUDIO, VIDEO, TYPE_COUNT };
+
+  /**
+   * Gets the total duration of the segment.
+   */
+  TrackTime GetDuration() const { return mDuration; }
+  Type GetType() const { return mType; }
+
+  /**
+   * Gets the last principal id that was appended to this segment.
+   */
+  const PrincipalHandle& GetLastPrincipalHandle() const {
+    return mLastPrincipalHandle;
+  }
+  /**
+   * Called by the MediaTrackGraph as it appends a chunk with a different
+   * principal id than the current one.
+   */
+  void SetLastPrincipalHandle(PrincipalHandle aLastPrincipalHandle) {
+    mLastPrincipalHandle = std::forward<PrincipalHandle>(aLastPrincipalHandle);
+  }
+
+  /**
+   * Returns true if all chunks in this segment are null.
+   */
+  virtual bool IsNull() const = 0;
+
+  /**
+   * Returns true if this segment contains no chunks.
+   */
+  virtual bool IsEmpty() const = 0;
+
+  /**
+   * Create a MediaSegment of the same type.
+   */
+  virtual MediaSegment* CreateEmptyClone() const = 0;
+  /**
+   * Moves contents of aSource to the end of this segment.
+   */
+  virtual void AppendFrom(MediaSegment* aSource) = 0;
+  /**
+   * Append a slice of aSource to this segment.
+   */
+  virtual void AppendSlice(const MediaSegment& aSource, TrackTime aStart,
+                           TrackTime aEnd) = 0;
+  /**
+   * Replace all contents up to aDuration with null data.
+   */
+  virtual void ForgetUpTo(TrackTime aDuration) = 0;
+  /**
+   * Forget all data buffered after a given point
+   */
+  virtual void FlushAfter(TrackTime aNewEnd) = 0;
+  /**
+   * Insert aDuration of null data at the start of the segment.
+   */
+  virtual void InsertNullDataAtStart(TrackTime aDuration) = 0;
+  /**
+   * Insert aDuration of null data at the end of the segment.
+   */
+  virtual void AppendNullData(TrackTime aDuration) = 0;
+  /**
+   * Replace contents with disabled (silence/black) data of the same duration
+   */
+  virtual void ReplaceWithDisabled() = 0;
+  /**
+   * Replace contents with null data of the same duration
+   */
+  virtual void ReplaceWithNull() = 0;
+  /**
+   * Remove all contents, setting duration to 0.
+   */
+  virtual void Clear() = 0;
+
+  virtual size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const {
+    return 0;
+  }
+
+  virtual size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+ protected:
+  explicit MediaSegment(Type aType)
+      : mDuration(0),
+        mType(aType),
+        mLastPrincipalHandle(PRINCIPAL_HANDLE_NONE) {
+    MOZ_COUNT_CTOR(MediaSegment);
+  }
+
+  MediaSegment(MediaSegment&& aSegment)
+      : mDuration(std::move(aSegment.mDuration)),
+        mType(std::move(aSegment.mType)),
+        mLastPrincipalHandle(std::move(aSegment.mLastPrincipalHandle)) {
+    MOZ_COUNT_CTOR(MediaSegment);
+  }
+
+  TrackTime mDuration;  // total of mDurations of all chunks
+  Type mType;
+
+  // The latest principal handle that the MediaTrackGraph has processed for
+  // this segment.
+  PrincipalHandle mLastPrincipalHandle;
+};
+
+/**
+ * C is the implementation class subclassed from MediaSegmentBase.
+ * C must contain a Chunk class.
+ */
+template <class C, class Chunk>
+class MediaSegmentBase : public MediaSegment {
+ public:
+  bool IsNull() const override {
+    for (typename C::ConstChunkIterator iter(*this); !iter.IsEnded();
+         iter.Next()) {
+      if (!iter->IsNull()) {
+        return false;
+      }
+    }
+    return true;
+  }
+  bool IsEmpty() const override { return mChunks.IsEmpty(); }
+  MediaSegment* CreateEmptyClone() const override { return new C(); }
+  void AppendFrom(MediaSegment* aSource) override {
+    NS_ASSERTION(aSource->GetType() == C::StaticType(), "Wrong type");
+    AppendFromInternal(static_cast<C*>(aSource));
+  }
+  void AppendFrom(C* aSource) { AppendFromInternal(aSource); }
+  void AppendSlice(const MediaSegment& aSource, TrackTime aStart,
+                   TrackTime aEnd) override {
+    NS_ASSERTION(aSource.GetType() == C::StaticType(), "Wrong type");
+    AppendSliceInternal(static_cast<const C&>(aSource), aStart, aEnd);
+  }
+  void AppendSlice(const C& aOther, TrackTime aStart, TrackTime aEnd) {
+    AppendSliceInternal(aOther, aStart, aEnd);
+  }
+  /**
+   * Replace the first aDuration ticks with null media data, because the data
+   * will not be required again.
+   */
+  void ForgetUpTo(TrackTime aDuration) override {
+    if (mChunks.IsEmpty() || aDuration <= 0) {
+      return;
+    }
+    if (mChunks[0].IsNull()) {
+      TrackTime extraToForget =
+          std::min(aDuration, mDuration) - mChunks[0].GetDuration();
+      if (extraToForget > 0) {
+        RemoveLeading(extraToForget, 1);
+        mChunks[0].mDuration += extraToForget;
+        mDuration += extraToForget;
+      }
+      return;
+    }
+    RemoveLeading(aDuration, 0);
+    mChunks.InsertElementAt(0)->SetNull(aDuration);
+    mDuration += aDuration;
+  }
+  void FlushAfter(TrackTime aNewEnd) override {
+    if (mChunks.IsEmpty()) {
+      return;
+    }
+
+    if (!aNewEnd) {
+      Clear();
+    } else if (mChunks[0].IsNull()) {
+      TrackTime extraToKeep = aNewEnd - mChunks[0].GetDuration();
+      if (extraToKeep < 0) {
+        // reduce the size of the Null, get rid of everthing else
+        mChunks[0].SetNull(aNewEnd);
+        extraToKeep = 0;
+      }
+      RemoveTrailing(extraToKeep, 1);
+    } else {
+      if (aNewEnd > mDuration) {
+        NS_ASSERTION(aNewEnd <= mDuration, "can't add data in FlushAfter");
+        return;
+      }
+      RemoveTrailing(aNewEnd, 0);
+    }
+    mDuration = aNewEnd;
+  }
+  void InsertNullDataAtStart(TrackTime aDuration) override {
+    if (aDuration <= 0) {
+      return;
+    }
+    if (!mChunks.IsEmpty() && mChunks[0].IsNull()) {
+      mChunks[0].mDuration += aDuration;
+    } else {
+      mChunks.InsertElementAt(0)->SetNull(aDuration);
+    }
+    mDuration += aDuration;
+  }
+  void AppendNullData(TrackTime aDuration) override {
+    if (aDuration <= 0) {
+      return;
+    }
+    if (!mChunks.IsEmpty() && mChunks[mChunks.Length() - 1].IsNull()) {
+      mChunks[mChunks.Length() - 1].mDuration += aDuration;
+    } else {
+      mChunks.AppendElement()->SetNull(aDuration);
+    }
+    mDuration += aDuration;
+  }
+  void ReplaceWithDisabled() override {
+    if (GetType() != AUDIO) {
+      MOZ_CRASH("Disabling unknown segment type");
+    }
+    ReplaceWithNull();
+  }
+  void ReplaceWithNull() override {
+    TrackTime duration = GetDuration();
+    Clear();
+    AppendNullData(duration);
+  }
+  void Clear() override {
+    mDuration = 0;
+    mChunks.ClearAndRetainStorage();
+    mChunks.SetCapacity(DEFAULT_SEGMENT_CAPACITY);
+  }
+
+  class ChunkIterator {
+   public:
+    explicit ChunkIterator(MediaSegmentBase<C, Chunk>& aSegment)
+        : mSegment(aSegment), mIndex(0) {}
+    bool IsEnded() { return mIndex >= mSegment.mChunks.Length(); }
+    void Next() { ++mIndex; }
+    Chunk& operator*() { return mSegment.mChunks[mIndex]; }
+    Chunk* operator->() { return &mSegment.mChunks[mIndex]; }
+
+   private:
+    MediaSegmentBase<C, Chunk>& mSegment;
+    uint32_t mIndex;
+  };
+  class ConstChunkIterator {
+   public:
+    explicit ConstChunkIterator(const MediaSegmentBase<C, Chunk>& aSegment)
+        : mSegment(aSegment), mIndex(0) {}
+    bool IsEnded() { return mIndex >= mSegment.mChunks.Length(); }
+    void Next() { ++mIndex; }
+    const Chunk& operator*() { return mSegment.mChunks[mIndex]; }
+    const Chunk* operator->() { return &mSegment.mChunks[mIndex]; }
+
+   private:
+    const MediaSegmentBase<C, Chunk>& mSegment;
+    uint32_t mIndex;
+  };
+
+  void RemoveLeading(TrackTime aDuration) { RemoveLeading(aDuration, 0); }
+
+  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const override {
+    size_t amount = mChunks.ShallowSizeOfExcludingThis(aMallocSizeOf);
+    for (size_t i = 0; i < mChunks.Length(); i++) {
+      amount += mChunks[i].SizeOfExcludingThisIfUnshared(aMallocSizeOf);
+    }
+    return amount;
+  }
+
+  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const override {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  Chunk* GetLastChunk() {
+    if (mChunks.IsEmpty()) {
+      return nullptr;
+    }
+    return &mChunks[mChunks.Length() - 1];
+  }
+
+  const Chunk* GetLastChunk() const {
+    if (mChunks.IsEmpty()) {
+      return nullptr;
+    }
+    return &mChunks[mChunks.Length() - 1];
+  }
+
+ protected:
+  explicit MediaSegmentBase(Type aType) : MediaSegment(aType), mChunks() {}
+
+  MediaSegmentBase(MediaSegmentBase&& aSegment)
+      : MediaSegment(std::move(aSegment)),
+        mChunks(std::move(aSegment.mChunks)) {
+    MOZ_ASSERT(mChunks.Capacity() >= DEFAULT_SEGMENT_CAPACITY,
+               "Capacity must be retained in self after swap");
+    MOZ_ASSERT(aSegment.mChunks.Capacity() >= DEFAULT_SEGMENT_CAPACITY,
+               "Capacity must be retained in other after swap");
+  }
+
+  /**
+   * Appends the contents of aSource to this segment, clearing aSource.
+   */
+  void AppendFromInternal(MediaSegmentBase<C, Chunk>* aSource) {
+    MOZ_ASSERT(aSource->mDuration >= 0);
+    mDuration += aSource->mDuration;
+    aSource->mDuration = 0;
+    size_t offset = 0;
+    if (!mChunks.IsEmpty() && !aSource->mChunks.IsEmpty() &&
+        mChunks[mChunks.Length() - 1].CanCombineWithFollowing(
+            aSource->mChunks[0])) {
+      mChunks[mChunks.Length() - 1].mDuration += aSource->mChunks[0].mDuration;
+      offset = 1;
+    }
+
+    for (; offset < aSource->mChunks.Length(); ++offset) {
+      mChunks.AppendElement(std::move(aSource->mChunks[offset]));
+    }
+
+    aSource->mChunks.ClearAndRetainStorage();
+    MOZ_ASSERT(aSource->mChunks.Capacity() >= DEFAULT_SEGMENT_CAPACITY,
+               "Capacity must be retained after appending from aSource");
+  }
+
+  void AppendSliceInternal(const MediaSegmentBase<C, Chunk>& aSource,
+                           TrackTime aStart, TrackTime aEnd) {
+    MOZ_ASSERT(aStart <= aEnd, "Endpoints inverted");
+    NS_ASSERTION(aStart >= 0 && aEnd <= aSource.mDuration,
+                 "Slice out of range");
+    mDuration += aEnd - aStart;
+    TrackTime offset = 0;
+    for (uint32_t i = 0; i < aSource.mChunks.Length() && offset < aEnd; ++i) {
+      const Chunk& c = aSource.mChunks[i];
+      TrackTime start = std::max(aStart, offset);
+      TrackTime nextOffset = offset + c.GetDuration();
+      TrackTime end = std::min(aEnd, nextOffset);
+      if (start < end) {
+        if (!mChunks.IsEmpty() &&
+            mChunks[mChunks.Length() - 1].CanCombineWithFollowing(c)) {
+          MOZ_ASSERT(start - offset >= 0 && end - offset <= aSource.mDuration,
+                     "Slice out of bounds");
+          mChunks[mChunks.Length() - 1].mDuration += end - start;
+        } else {
+          mChunks.AppendElement(c)->SliceTo(start - offset, end - offset);
+        }
+      }
+      offset = nextOffset;
+    }
+  }
+
+  Chunk* AppendChunk(TrackTime aDuration) {
+    MOZ_ASSERT(aDuration >= 0);
+    Chunk* c = mChunks.AppendElement();
+    c->mDuration = aDuration;
+    mDuration += aDuration;
+    return c;
+  }
+
+  void RemoveLeading(TrackTime aDuration, uint32_t aStartIndex) {
+    NS_ASSERTION(aDuration >= 0, "Can't remove negative duration");
+    TrackTime t = aDuration;
+    uint32_t chunksToRemove = 0;
+    for (uint32_t i = aStartIndex; i < mChunks.Length() && t > 0; ++i) {
+      Chunk* c = &mChunks[i];
+      if (c->GetDuration() > t) {
+        c->SliceTo(t, c->GetDuration());
+        t = 0;
+        break;
+      }
+      t -= c->GetDuration();
+      chunksToRemove = i + 1 - aStartIndex;
+    }
+    if (aStartIndex == 0 && chunksToRemove == mChunks.Length()) {
+      mChunks.ClearAndRetainStorage();
+    } else {
+      mChunks.RemoveElementsAt(aStartIndex, chunksToRemove);
+    }
+    mDuration -= aDuration - t;
+
+    MOZ_ASSERT(mChunks.Capacity() >= DEFAULT_SEGMENT_CAPACITY,
+               "Capacity must be retained after removing chunks");
+  }
+
+  void RemoveTrailing(TrackTime aKeep, uint32_t aStartIndex) {
+    NS_ASSERTION(aKeep >= 0, "Can't keep negative duration");
+    TrackTime t = aKeep;
+    uint32_t i;
+    for (i = aStartIndex; i < mChunks.Length() && t; ++i) {
+      Chunk* c = &mChunks[i];
+      if (c->GetDuration() > t) {
+        c->SliceTo(0, t);
+        break;
+      }
+      t -= c->GetDuration();
+    }
+    // At this point `i` is already advanced due to last check in the loop.
+    if (i < mChunks.Length()) {
+      mChunks.RemoveLastElements(mChunks.Length() - i);
+    }
+    MOZ_ASSERT(mChunks.Capacity() >= DEFAULT_SEGMENT_CAPACITY,
+               "Capacity must be retained after removing chunks");
+    // Caller must adjust mDuration
+  }
+
+  AutoTArray<Chunk, DEFAULT_SEGMENT_CAPACITY> mChunks;
+};
+
+}  // namespace mozilla
+
+#endif /* MOZILLA_MEDIASEGMENT_H_ */