third_party/WebKit/Source/modules/webaudio/MediaStreamAudioDestinationNode.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.
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 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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#include "modules/webaudio/MediaStreamAudioDestinationNode.h"
#include "bindings/core/v8/ExceptionMessages.h"
#include "bindings/core/v8/ExceptionState.h"
#include "core/dom/ExceptionCode.h"
#include "modules/webaudio/AudioNodeInput.h"
#include "modules/webaudio/BaseAudioContext.h"
#include "platform/UUID.h"
#include "platform/mediastream/MediaStreamCenter.h"
#include "public/platform/WebRTCPeerConnectionHandler.h"
#include "wtf/Locker.h"

namespace blink {

// WebAudioCapturerSource ignores the channel count beyond 8, so we set the
// block here to avoid anything can cause the crash.
static const unsigned long kMaxChannelCount = 8;

MediaStreamAudioDestinationHandler::MediaStreamAudioDestinationHandler(
    AudioNode& node,
    size_t numberOfChannels)
    : AudioBasicInspectorHandler(NodeTypeMediaStreamAudioDestination,
                                 node,
                                 node.context()->sampleRate(),
                                 numberOfChannels),
      m_mixBus(AudioBus::create(numberOfChannels, ProcessingSizeInFrames)) {
  m_source = MediaStreamSource::create(
      "WebAudio-" + createCanonicalUUIDString(), MediaStreamSource::TypeAudio,
      "MediaStreamAudioDestinationNode", false,
      MediaStreamSource::ReadyStateLive, true);
  MediaStreamSourceVector audioSources;
  audioSources.append(m_source.get());
  MediaStreamSourceVector videoSources;
  m_stream = MediaStream::create(
      node.context()->getExecutionContext(),
      MediaStreamDescriptor::create(audioSources, videoSources));
  MediaStreamCenter::instance().didCreateMediaStreamAndTracks(
      m_stream->descriptor());

  m_source->setAudioFormat(numberOfChannels, node.context()->sampleRate());

  initialize();
}

PassRefPtr<MediaStreamAudioDestinationHandler>
MediaStreamAudioDestinationHandler::create(AudioNode& node,
                                           size_t numberOfChannels) {
  return adoptRef(
      new MediaStreamAudioDestinationHandler(node, numberOfChannels));
}

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

void MediaStreamAudioDestinationHandler::process(size_t numberOfFrames) {
  // Conform the input bus into the internal mix bus, which represents
  // MediaStreamDestination's channel count.
  m_mixBus->copyFrom(*input(0).bus());

  m_source->consumeAudio(m_mixBus.get(), numberOfFrames);
}

void MediaStreamAudioDestinationHandler::setChannelCount(
    unsigned long channelCount,
    ExceptionState& exceptionState) {
  DCHECK(isMainThread());

  // Currently the maximum channel count supported for this node is 8,
  // which is constrained by m_source (WebAudioCapturereSource). Although
  // it has its own safety check for the excessive channels, throwing an
  // exception here is useful to developers.
  if (channelCount > maxChannelCount()) {
    exceptionState.throwDOMException(
        IndexSizeError,
        ExceptionMessages::indexOutsideRange<unsigned>(
            "channel count", channelCount, 1, ExceptionMessages::InclusiveBound,
            maxChannelCount(), ExceptionMessages::InclusiveBound));
    return;
  }

  unsigned long oldChannelCount = this->channelCount();
  AudioHandler::setChannelCount(channelCount, exceptionState);

  // Update the pipeline with the new channel count only if absolutely
  // necessary. This process requires the graph lock.
  //
  // TODO(hongchan): There might be a data race here since both threads
  // have access to m_mixBus.
  if (!exceptionState.hadException() &&
      this->channelCount() != oldChannelCount && isInitialized()) {
    BaseAudioContext::AutoLocker locker(context());
    m_mixBus = AudioBus::create(channelCount, ProcessingSizeInFrames);
    m_source->setAudioFormat(channelCount, context()->sampleRate());
  }
}

unsigned long MediaStreamAudioDestinationHandler::maxChannelCount() const {
  return kMaxChannelCount;
}

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

MediaStreamAudioDestinationNode::MediaStreamAudioDestinationNode(
    BaseAudioContext& context,
    size_t numberOfChannels)
    : AudioBasicInspectorNode(context) {
  setHandler(
      MediaStreamAudioDestinationHandler::create(*this, numberOfChannels));
}

MediaStreamAudioDestinationNode* MediaStreamAudioDestinationNode::create(
    BaseAudioContext& context,
    size_t numberOfChannels,
    ExceptionState& exceptionState) {
  DCHECK(isMainThread());

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

  return new MediaStreamAudioDestinationNode(context, numberOfChannels);
}

MediaStream* MediaStreamAudioDestinationNode::stream() const {
  return static_cast<MediaStreamAudioDestinationHandler&>(handler()).stream();
}

}  // namespace blink