1 files changed, 119 insertions, 0 deletions
diff --git a/dom/media/driftcontrol/AudioChunkList.cpp b/dom/media/driftcontrol/AudioChunkList.cpp
new file mode 100644
index 0000000000..e0010c2ff0
--- /dev/null
+++ b/dom/media/driftcontrol/AudioChunkList.cpp
@@ -0,0 +1,119 @@
+/* -*- 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 "AudioChunkList.h"
+
+namespace mozilla {
+
+AudioChunkList::AudioChunkList(uint32_t aTotalDuration, uint32_t aChannels,
+                               const PrincipalHandle& aPrincipalHandle)
+    : mPrincipalHandle(aPrincipalHandle) {
+  uint32_t numOfChunks = aTotalDuration / mChunkCapacity;
+  if (aTotalDuration % mChunkCapacity) {
+    ++numOfChunks;
+  }
+  CreateChunks(numOfChunks, aChannels);
+}
+
+void AudioChunkList::CreateChunks(uint32_t aNumOfChunks, uint32_t aChannels) {
+  MOZ_ASSERT(!mChunks.Length());
+  MOZ_ASSERT(aNumOfChunks);
+  MOZ_ASSERT(aChannels);
+  mChunks.AppendElements(aNumOfChunks);
+
+  for (AudioChunk& chunk : mChunks) {
+    AutoTArray<nsTArray<float>, 2> buffer;
+    buffer.AppendElements(aChannels);
+
+    AutoTArray<const float*, 2> bufferPtrs;
+    bufferPtrs.AppendElements(aChannels);
+
+    for (uint32_t i = 0; i < aChannels; ++i) {
+      float* ptr = buffer[i].AppendElements(mChunkCapacity);
+      bufferPtrs[i] = ptr;
+    }
+
+    chunk.mBuffer = new mozilla::SharedChannelArrayBuffer(std::move(buffer));
+    chunk.mChannelData.AppendElements(aChannels);
+    for (uint32_t i = 0; i < aChannels; ++i) {
+      chunk.mChannelData[i] = bufferPtrs[i];
+    }
+  }
+}
+
+void AudioChunkList::UpdateToMonoOrStereo(uint32_t aChannels) {
+  MOZ_ASSERT(mChunks.Length());
+  MOZ_ASSERT(mSampleFormat == AUDIO_FORMAT_S16 ||
+             mSampleFormat == AUDIO_FORMAT_FLOAT32);
+  MOZ_ASSERT(aChannels == 1 || aChannels == 2);
+
+  for (AudioChunk& chunk : mChunks) {
+    MOZ_ASSERT(chunk.ChannelCount() != (uint32_t)aChannels);
+    MOZ_ASSERT(chunk.ChannelCount() == 1 || chunk.ChannelCount() == 2);
+    chunk.mChannelData.SetLengthAndRetainStorage(aChannels);
+    if (mSampleFormat == AUDIO_FORMAT_S16) {
+      SharedChannelArrayBuffer<short>* channelArray =
+          static_cast<SharedChannelArrayBuffer<short>*>(chunk.mBuffer.get());
+      channelArray->mBuffers.SetLengthAndRetainStorage(aChannels);
+      if (aChannels == 2) {
+        // This an indirect allocation, unfortunately.
+        channelArray->mBuffers[1].SetLength(mChunkCapacity);
+        chunk.mChannelData[1] = channelArray->mBuffers[1].Elements();
+      }
+    } else {
+      SharedChannelArrayBuffer<float>* channelArray =
+          static_cast<SharedChannelArrayBuffer<float>*>(chunk.mBuffer.get());
+      channelArray->mBuffers.SetLengthAndRetainStorage(aChannels);
+      if (aChannels == 2) {
+        // This an indirect allocation, unfortunately.
+        channelArray->mBuffers[1].SetLength(mChunkCapacity);
+        chunk.mChannelData[1] = channelArray->mBuffers[1].Elements();
+      }
+    }
+  }
+}
+
+void AudioChunkList::SetSampleFormat(AudioSampleFormat aFormat) {
+  MOZ_ASSERT(mSampleFormat == AUDIO_FORMAT_SILENCE);
+  MOZ_ASSERT(aFormat == AUDIO_FORMAT_S16 || aFormat == AUDIO_FORMAT_FLOAT32);
+  mSampleFormat = aFormat;
+  if (mSampleFormat == AUDIO_FORMAT_S16) {
+    mChunkCapacity = 2 * mChunkCapacity;
+  }
+}
+
+AudioChunk& AudioChunkList::GetNext() {
+  AudioChunk& chunk = mChunks[mIndex];
+  MOZ_ASSERT(!chunk.mChannelData.IsEmpty());
+  MOZ_ASSERT(chunk.mBuffer);
+  MOZ_ASSERT(!chunk.mBuffer->IsShared());
+  MOZ_ASSERT(mSampleFormat == AUDIO_FORMAT_S16 ||
+             mSampleFormat == AUDIO_FORMAT_FLOAT32);
+  chunk.mDuration = 0;
+  chunk.mVolume = 1.0f;
+  chunk.mPrincipalHandle = mPrincipalHandle;
+  chunk.mBufferFormat = mSampleFormat;
+  IncrementIndex();
+  return chunk;
+}
+
+void AudioChunkList::Update(uint32_t aChannels) {
+  MOZ_ASSERT(mChunks.Length());
+  if (mChunks[0].ChannelCount() == aChannels) {
+    return;
+  }
+
+  // Special handling between mono and stereo to avoid reallocations.
+  if (aChannels <= 2 && mChunks[0].ChannelCount() <= 2) {
+    UpdateToMonoOrStereo(aChannels);
+    return;
+  }
+
+  uint32_t numOfChunks = mChunks.Length();
+  mChunks.ClearAndRetainStorage();
+  CreateChunks(numOfChunks, aChannels);
+}
+
+}  // namespace mozilla