1 files changed, 139 insertions, 0 deletions
diff --git a/dom/media/AudioCaptureTrack.cpp b/dom/media/AudioCaptureTrack.cpp
new file mode 100644
index 0000000000..f30581ee69
--- /dev/null
+++ b/dom/media/AudioCaptureTrack.cpp
@@ -0,0 +1,139 @@
+/* -*- 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 "MediaTrackGraphImpl.h"
+#include "MediaTrackListener.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/Unused.h"
+
+#include "AudioSegment.h"
+#include "mozilla/Logging.h"
+#include "mozilla/Attributes.h"
+#include "AudioCaptureTrack.h"
+#include "ImageContainer.h"
+#include "AudioNodeEngine.h"
+#include "AudioNodeTrack.h"
+#include "AudioNodeExternalInputTrack.h"
+#include "webaudio/MediaStreamAudioDestinationNode.h"
+#include <algorithm>
+#include "DOMMediaStream.h"
+
+using namespace mozilla::layers;
+using namespace mozilla::dom;
+using namespace mozilla::gfx;
+
+namespace mozilla {
+
+// We are mixing to mono until PeerConnection can accept stereo
+static const uint32_t MONO = 1;
+
+AudioCaptureTrack::AudioCaptureTrack(TrackRate aRate)
+    : ProcessedMediaTrack(aRate, MediaSegment::AUDIO, new AudioSegment()),
+      mStarted(false) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_COUNT_CTOR(AudioCaptureTrack);
+  mMixer.AddCallback(WrapNotNull(this));
+}
+
+AudioCaptureTrack::~AudioCaptureTrack() {
+  MOZ_COUNT_DTOR(AudioCaptureTrack);
+  mMixer.RemoveCallback(this);
+}
+
+void AudioCaptureTrack::Start() {
+  class Message : public ControlMessage {
+   public:
+    explicit Message(AudioCaptureTrack* aTrack)
+        : ControlMessage(aTrack), mTrack(aTrack) {}
+
+    virtual void Run() { mTrack->mStarted = true; }
+
+   protected:
+    AudioCaptureTrack* mTrack;
+  };
+  GraphImpl()->AppendMessage(MakeUnique<Message>(this));
+}
+
+void AudioCaptureTrack::ProcessInput(GraphTime aFrom, GraphTime aTo,
+                                     uint32_t aFlags) {
+  if (!mStarted) {
+    return;
+  }
+
+  uint32_t inputCount = mInputs.Length();
+
+  if (mEnded) {
+    return;
+  }
+
+  // If the captured track is connected back to a object on the page (be it an
+  // HTMLMediaElement with a track as source, or an AudioContext), a cycle
+  // situation occur. This can work if it's an AudioContext with at least one
+  // DelayNode, but the MTG will mute the whole cycle otherwise.
+  if (InMutedCycle() || inputCount == 0) {
+    GetData<AudioSegment>()->AppendNullData(aTo - aFrom);
+  } else {
+    // We mix down all the tracks of all inputs, to a stereo track. Everything
+    // is {up,down}-mixed to stereo.
+    mMixer.StartMixing();
+    AudioSegment output;
+    for (uint32_t i = 0; i < inputCount; i++) {
+      MediaTrack* s = mInputs[i]->GetSource();
+      AudioSegment* inputSegment = s->GetData<AudioSegment>();
+      TrackTime inputStart = s->GraphTimeToTrackTimeWithBlocking(aFrom);
+      TrackTime inputEnd = s->GraphTimeToTrackTimeWithBlocking(aTo);
+      AudioSegment toMix;
+      if (s->Ended() && inputSegment->GetDuration() <= inputStart) {
+        toMix.AppendNullData(aTo - aFrom);
+      } else {
+        toMix.AppendSlice(*inputSegment, inputStart, inputEnd);
+        // Care for tracks blocked in the [aTo, aFrom] range.
+        if (inputEnd - inputStart < aTo - aFrom) {
+          toMix.AppendNullData((aTo - aFrom) - (inputEnd - inputStart));
+        }
+      }
+      toMix.Mix(mMixer, MONO, Graph()->GraphRate());
+    }
+    // This calls MixerCallback below
+    mMixer.FinishMixing();
+  }
+}
+
+uint32_t AudioCaptureTrack::NumberOfChannels() const {
+  return GetData<AudioSegment>()->MaxChannelCount();
+}
+
+void AudioCaptureTrack::MixerCallback(AudioDataValue* aMixedBuffer,
+                                      AudioSampleFormat aFormat,
+                                      uint32_t aChannels, uint32_t aFrames,
+                                      uint32_t aSampleRate) {
+  AutoTArray<nsTArray<AudioDataValue>, MONO> output;
+  AutoTArray<const AudioDataValue*, MONO> bufferPtrs;
+  output.SetLength(MONO);
+  bufferPtrs.SetLength(MONO);
+
+  uint32_t written = 0;
+  // We need to copy here, because the mixer will reuse the storage, we should
+  // not hold onto it. Buffers are in planar format.
+  for (uint32_t channel = 0; channel < aChannels; channel++) {
+    AudioDataValue* out = output[channel].AppendElements(aFrames);
+    PodCopy(out, aMixedBuffer + written, aFrames);
+    bufferPtrs[channel] = out;
+    written += aFrames;
+  }
+  AudioChunk chunk;
+  chunk.mBuffer =
+      new mozilla::SharedChannelArrayBuffer<AudioDataValue>(std::move(output));
+  chunk.mDuration = aFrames;
+  chunk.mBufferFormat = aFormat;
+  chunk.mChannelData.SetLength(MONO);
+  for (uint32_t channel = 0; channel < aChannels; channel++) {
+    chunk.mChannelData[channel] = bufferPtrs[channel];
+  }
+
+  // Now we have mixed data, simply append it.
+  GetData<AudioSegment>()->AppendAndConsumeChunk(std::move(chunk));
+}
+}  // namespace mozilla