third_party/WebKit/Source/modules/webaudio/MediaStreamAudioSourceNode.cpp

/*
 * Copyright (C) 2012, Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1.  Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 */

#include "modules/webaudio/MediaStreamAudioSourceNode.h"

#include "core/dom/ExceptionCode.h"
#include "modules/webaudio/AudioNodeOutput.h"
#include "modules/webaudio/BaseAudioContext.h"
#include "wtf/Locker.h"
#include <memory>

namespace blink {

MediaStreamAudioSourceHandler::MediaStreamAudioSourceHandler(
    AudioNode& node,
    MediaStream& mediaStream,
    MediaStreamTrack* audioTrack,
    std::unique_ptr<AudioSourceProvider> audioSourceProvider)
    : AudioHandler(NodeTypeMediaStreamAudioSource,
                   node,
                   node.context()->sampleRate()),
      m_mediaStream(mediaStream),
      m_audioTrack(audioTrack),
      m_audioSourceProvider(std::move(audioSourceProvider)),
      m_sourceNumberOfChannels(0) {
  // Default to stereo. This could change depending on the format of the
  // MediaStream's audio track.
  addOutput(2);

  initialize();
}

PassRefPtr<MediaStreamAudioSourceHandler> MediaStreamAudioSourceHandler::create(
    AudioNode& node,
    MediaStream& mediaStream,
    MediaStreamTrack* audioTrack,
    std::unique_ptr<AudioSourceProvider> audioSourceProvider) {
  return adoptRef(new MediaStreamAudioSourceHandler(
      node, mediaStream, audioTrack, std::move(audioSourceProvider)));
}

MediaStreamAudioSourceHandler::~MediaStreamAudioSourceHandler() {
  uninitialize();
}

void MediaStreamAudioSourceHandler::setFormat(size_t numberOfChannels,
                                              float sourceSampleRate) {
  if (numberOfChannels != m_sourceNumberOfChannels ||
      sourceSampleRate != sampleRate()) {
    // The sample-rate must be equal to the context's sample-rate.
    if (!numberOfChannels ||
        numberOfChannels > BaseAudioContext::maxNumberOfChannels() ||
        sourceSampleRate != sampleRate()) {
      // process() will generate silence for these uninitialized values.
      DLOG(ERROR) << "setFormat(" << numberOfChannels << ", "
                  << sourceSampleRate << ") - unhandled format change";
      m_sourceNumberOfChannels = 0;
      return;
    }

    // Synchronize with process().
    MutexLocker locker(m_processLock);

    m_sourceNumberOfChannels = numberOfChannels;

    {
      // The context must be locked when changing the number of output channels.
      BaseAudioContext::AutoLocker contextLocker(context());

      // Do any necesssary re-configuration to the output's number of channels.
      output(0).setNumberOfChannels(numberOfChannels);
    }
  }
}

void MediaStreamAudioSourceHandler::process(size_t numberOfFrames) {
  AudioBus* outputBus = output(0).bus();

  if (!getAudioSourceProvider()) {
    outputBus->zero();
    return;
  }

  if (!getMediaStream() ||
      m_sourceNumberOfChannels != outputBus->numberOfChannels()) {
    outputBus->zero();
    return;
  }

  // Use a tryLock() to avoid contention in the real-time audio thread.
  // If we fail to acquire the lock then the MediaStream must be in the middle
  // of a format change, so we output silence in this case.
  MutexTryLocker tryLocker(m_processLock);
  if (tryLocker.locked()) {
    getAudioSourceProvider()->provideInput(outputBus, numberOfFrames);
  } else {
    // We failed to acquire the lock.
    outputBus->zero();
  }
}

// ----------------------------------------------------------------

MediaStreamAudioSourceNode::MediaStreamAudioSourceNode(
    BaseAudioContext& context,
    MediaStream& mediaStream,
    MediaStreamTrack* audioTrack,
    std::unique_ptr<AudioSourceProvider> audioSourceProvider)
    : AudioSourceNode(context) {
  setHandler(MediaStreamAudioSourceHandler::create(
      *this, mediaStream, audioTrack, std::move(audioSourceProvider)));
}

MediaStreamAudioSourceNode* MediaStreamAudioSourceNode::create(
    BaseAudioContext& context,
    MediaStream& mediaStream,
    ExceptionState& exceptionState) {
  DCHECK(isMainThread());

  if (context.isContextClosed()) {
    context.throwExceptionForClosedState(exceptionState);
    return nullptr;
  }

  MediaStreamTrackVector audioTracks = mediaStream.getAudioTracks();
  if (audioTracks.isEmpty()) {
    exceptionState.throwDOMException(InvalidStateError,
                                     "MediaStream has no audio track");
    return nullptr;
  }

  // Use the first audio track in the media stream.
  MediaStreamTrack* audioTrack = audioTracks[0];
  std::unique_ptr<AudioSourceProvider> provider =
      audioTrack->createWebAudioSource();

  MediaStreamAudioSourceNode* node = new MediaStreamAudioSourceNode(
      context, mediaStream, audioTrack, std::move(provider));

  if (!node)
    return nullptr;

  // TODO(hongchan): Only stereo streams are supported right now. We should be
  // able to accept multi-channel streams.
  node->setFormat(2, context.sampleRate());
  // context keeps reference until node is disconnected
  context.notifySourceNodeStartedProcessing(node);

  return node;
}

DEFINE_TRACE(MediaStreamAudioSourceNode) {
  AudioSourceProviderClient::trace(visitor);
  AudioSourceNode::trace(visitor);
}

MediaStreamAudioSourceHandler&
MediaStreamAudioSourceNode::mediaStreamAudioSourceHandler() const {
  return static_cast<MediaStreamAudioSourceHandler&>(handler());
}

MediaStream* MediaStreamAudioSourceNode::getMediaStream() const {
  return mediaStreamAudioSourceHandler().getMediaStream();
}

void MediaStreamAudioSourceNode::setFormat(size_t numberOfChannels,
                                           float sourceSampleRate) {
  mediaStreamAudioSourceHandler().setFormat(numberOfChannels, sourceSampleRate);
}

}  // namespace blink