dom/media/driftcontrol/AudioChunkList.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
   4  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "AudioChunkList.h"
   7
   8 namespace mozilla {
   9
  10 AudioChunkList::AudioChunkList(uint32_t aTotalDuration, uint32_t aChannels,
  11                                const PrincipalHandle& aPrincipalHandle)
  12     : mPrincipalHandle(aPrincipalHandle) {
  13   uint32_t numOfChunks = aTotalDuration / mChunkCapacity;
  14   if (aTotalDuration % mChunkCapacity) {
  15     ++numOfChunks;
  16   }
  17   CreateChunks(numOfChunks, aChannels);
  18 }
  19
  20 void AudioChunkList::CreateChunks(uint32_t aNumOfChunks, uint32_t aChannels) {
  21   MOZ_ASSERT(!mChunks.Length());
  22   MOZ_ASSERT(aNumOfChunks);
  23   MOZ_ASSERT(aChannels);
  24   mChunks.AppendElements(aNumOfChunks);
  25
  26   for (AudioChunk& chunk : mChunks) {
  27     AutoTArray<nsTArray<float>, 2> buffer;
  28     buffer.AppendElements(aChannels);
  29
  30     AutoTArray<const float*, 2> bufferPtrs;
  31     bufferPtrs.AppendElements(aChannels);
  32
  33     for (uint32_t i = 0; i < aChannels; ++i) {
  34       float* ptr = buffer[i].AppendElements(mChunkCapacity);
  35       bufferPtrs[i] = ptr;
  36     }
  37
  38     chunk.mBuffer = new mozilla::SharedChannelArrayBuffer(std::move(buffer));
  39     chunk.mChannelData.AppendElements(aChannels);
  40     for (uint32_t i = 0; i < aChannels; ++i) {
  41       chunk.mChannelData[i] = bufferPtrs[i];
  42     }
  43   }
  44 }
  45
  46 void AudioChunkList::UpdateToMonoOrStereo(uint32_t aChannels) {
  47   MOZ_ASSERT(mChunks.Length());
  48   MOZ_ASSERT(mSampleFormat == AUDIO_FORMAT_S16 ||
  49              mSampleFormat == AUDIO_FORMAT_FLOAT32);
  50   MOZ_ASSERT(aChannels == 1 || aChannels == 2);
  51
  52   for (AudioChunk& chunk : mChunks) {
  53     MOZ_ASSERT(chunk.ChannelCount() != (uint32_t)aChannels);
  54     MOZ_ASSERT(chunk.ChannelCount() == 1 || chunk.ChannelCount() == 2);
  55     chunk.mChannelData.SetLengthAndRetainStorage(aChannels);
  56     if (mSampleFormat == AUDIO_FORMAT_S16) {
  57       SharedChannelArrayBuffer<short>* channelArray =
  58           static_cast<SharedChannelArrayBuffer<short>*>(chunk.mBuffer.get());
  59       channelArray->mBuffers.SetLengthAndRetainStorage(aChannels);
  60       if (aChannels == 2) {
  61         // This an indirect allocation, unfortunately.
  62         channelArray->mBuffers[1].SetLength(mChunkCapacity);
  63         chunk.mChannelData[1] = channelArray->mBuffers[1].Elements();
  64       }
  65     } else {
  66       SharedChannelArrayBuffer<float>* channelArray =
  67           static_cast<SharedChannelArrayBuffer<float>*>(chunk.mBuffer.get());
  68       channelArray->mBuffers.SetLengthAndRetainStorage(aChannels);
  69       if (aChannels == 2) {
  70         // This an indirect allocation, unfortunately.
  71         channelArray->mBuffers[1].SetLength(mChunkCapacity);
  72         chunk.mChannelData[1] = channelArray->mBuffers[1].Elements();
  73       }
  74     }
  75   }
  76 }
  77
  78 void AudioChunkList::SetSampleFormat(AudioSampleFormat aFormat) {
  79   MOZ_ASSERT(mSampleFormat == AUDIO_FORMAT_SILENCE);
  80   MOZ_ASSERT(aFormat == AUDIO_FORMAT_S16 || aFormat == AUDIO_FORMAT_FLOAT32);
  81   mSampleFormat = aFormat;
  82   if (mSampleFormat == AUDIO_FORMAT_S16) {
  83     mChunkCapacity = 2 * mChunkCapacity;
  84   }
  85 }
  86
  87 AudioChunk& AudioChunkList::GetNext() {
  88   AudioChunk& chunk = mChunks[mIndex];
  89   MOZ_ASSERT(!chunk.mChannelData.IsEmpty());
  90   MOZ_ASSERT(chunk.mBuffer);
  91   MOZ_ASSERT(!chunk.mBuffer->IsShared());
  92   MOZ_ASSERT(mSampleFormat == AUDIO_FORMAT_S16 ||
  93              mSampleFormat == AUDIO_FORMAT_FLOAT32);
  94   chunk.mDuration = 0;
  95   chunk.mVolume = 1.0f;
  96   chunk.mPrincipalHandle = mPrincipalHandle;
  97   chunk.mBufferFormat = mSampleFormat;
  98   IncrementIndex();
  99   return chunk;
 100 }
 101
 102 void AudioChunkList::Update(uint32_t aChannels) {
 103   MOZ_ASSERT(mChunks.Length());
 104   if (mChunks[0].ChannelCount() == aChannels) {
 105     return;
 106   }
 107
 108   // Special handling between mono and stereo to avoid reallocations.
 109   if (aChannels <= 2 && mChunks[0].ChannelCount() <= 2) {
 110     UpdateToMonoOrStereo(aChannels);
 111     return;
 112   }
 113
 114   uint32_t numOfChunks = mChunks.Length();
 115   mChunks.ClearAndRetainStorage();
 116   CreateChunks(numOfChunks, aChannels);
 117 }
 118
 119 }  // namespace mozilla