dom/media/AudioCaptureTrack.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 "MediaTrackGraphImpl.h"
   7 #include "MediaTrackListener.h"
   8 #include "mozilla/MathAlgorithms.h"
   9 #include "mozilla/Unused.h"
  10
  11 #include "AudioSegment.h"
  12 #include "mozilla/Logging.h"
  13 #include "mozilla/Attributes.h"
  14 #include "AudioCaptureTrack.h"
  15 #include "ImageContainer.h"
  16 #include "AudioNodeEngine.h"
  17 #include "AudioNodeTrack.h"
  18 #include "AudioNodeExternalInputTrack.h"
  19 #include "webaudio/MediaStreamAudioDestinationNode.h"
  20 #include <algorithm>
  21 #include "DOMMediaStream.h"
  22
  23 using namespace mozilla::layers;
  24 using namespace mozilla::dom;
  25 using namespace mozilla::gfx;
  26
  27 namespace mozilla {
  28
  29 // We are mixing to mono until PeerConnection can accept stereo
  30 static const uint32_t MONO = 1;
  31
  32 AudioCaptureTrack::AudioCaptureTrack(TrackRate aRate)
  33     : ProcessedMediaTrack(aRate, MediaSegment::AUDIO, new AudioSegment()),
  34       mStarted(false) {
  35   MOZ_ASSERT(NS_IsMainThread());
  36   MOZ_COUNT_CTOR(AudioCaptureTrack);
  37   mMixer.AddCallback(WrapNotNull(this));
  38 }
  39
  40 AudioCaptureTrack::~AudioCaptureTrack() {
  41   MOZ_COUNT_DTOR(AudioCaptureTrack);
  42   mMixer.RemoveCallback(this);
  43 }
  44
  45 void AudioCaptureTrack::Start() {
  46   class Message : public ControlMessage {
  47    public:
  48     explicit Message(AudioCaptureTrack* aTrack)
  49         : ControlMessage(aTrack), mTrack(aTrack) {}
  50
  51     virtual void Run() { mTrack->mStarted = true; }
  52
  53    protected:
  54     AudioCaptureTrack* mTrack;
  55   };
  56   GraphImpl()->AppendMessage(MakeUnique<Message>(this));
  57 }
  58
  59 void AudioCaptureTrack::ProcessInput(GraphTime aFrom, GraphTime aTo,
  60                                      uint32_t aFlags) {
  61   if (!mStarted) {
  62     return;
  63   }
  64
  65   uint32_t inputCount = mInputs.Length();
  66
  67   if (mEnded) {
  68     return;
  69   }
  70
  71   // If the captured track is connected back to a object on the page (be it an
  72   // HTMLMediaElement with a track as source, or an AudioContext), a cycle
  73   // situation occur. This can work if it's an AudioContext with at least one
  74   // DelayNode, but the MTG will mute the whole cycle otherwise.
  75   if (InMutedCycle() || inputCount == 0) {
  76     GetData<AudioSegment>()->AppendNullData(aTo - aFrom);
  77   } else {
  78     // We mix down all the tracks of all inputs, to a stereo track. Everything
  79     // is {up,down}-mixed to stereo.
  80     mMixer.StartMixing();
  81     AudioSegment output;
  82     for (uint32_t i = 0; i < inputCount; i++) {
  83       MediaTrack* s = mInputs[i]->GetSource();
  84       AudioSegment* inputSegment = s->GetData<AudioSegment>();
  85       TrackTime inputStart = s->GraphTimeToTrackTimeWithBlocking(aFrom);
  86       TrackTime inputEnd = s->GraphTimeToTrackTimeWithBlocking(aTo);
  87       AudioSegment toMix;
  88       if (s->Ended() && inputSegment->GetDuration() <= inputStart) {
  89         toMix.AppendNullData(aTo - aFrom);
  90       } else {
  91         toMix.AppendSlice(*inputSegment, inputStart, inputEnd);
  92         // Care for tracks blocked in the [aTo, aFrom] range.
  93         if (inputEnd - inputStart < aTo - aFrom) {
  94           toMix.AppendNullData((aTo - aFrom) - (inputEnd - inputStart));
  95         }
  96       }
  97       toMix.Mix(mMixer, MONO, Graph()->GraphRate());
  98     }
  99     // This calls MixerCallback below
 100     mMixer.FinishMixing();
 101   }
 102 }
 103
 104 uint32_t AudioCaptureTrack::NumberOfChannels() const {
 105   return GetData<AudioSegment>()->MaxChannelCount();
 106 }
 107
 108 void AudioCaptureTrack::MixerCallback(AudioDataValue* aMixedBuffer,
 109                                       AudioSampleFormat aFormat,
 110                                       uint32_t aChannels, uint32_t aFrames,
 111                                       uint32_t aSampleRate) {
 112   AutoTArray<nsTArray<AudioDataValue>, MONO> output;
 113   AutoTArray<const AudioDataValue*, MONO> bufferPtrs;
 114   output.SetLength(MONO);
 115   bufferPtrs.SetLength(MONO);
 116
 117   uint32_t written = 0;
 118   // We need to copy here, because the mixer will reuse the storage, we should
 119   // not hold onto it. Buffers are in planar format.
 120   for (uint32_t channel = 0; channel < aChannels; channel++) {
 121     AudioDataValue* out = output[channel].AppendElements(aFrames);
 122     PodCopy(out, aMixedBuffer + written, aFrames);
 123     bufferPtrs[channel] = out;
 124     written += aFrames;
 125   }
 126   AudioChunk chunk;
 127   chunk.mBuffer =
 128       new mozilla::SharedChannelArrayBuffer<AudioDataValue>(std::move(output));
 129   chunk.mDuration = aFrames;
 130   chunk.mBufferFormat = aFormat;
 131   chunk.mChannelData.SetLength(MONO);
 132   for (uint32_t channel = 0; channel < aChannels; channel++) {
 133     chunk.mChannelData[channel] = bufferPtrs[channel];
 134   }
 135
 136   // Now we have mixed data, simply append it.
 137   GetData<AudioSegment>()->AppendAndConsumeChunk(std::move(chunk));
 138 }
 139 }  // namespace mozilla