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

/*
 * Copyright (C) 2012, Google Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
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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/AbstractAudioContext.h"
#include "modules/webaudio/AudioNodeInput.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)
{
    ASSERT(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()) {
        AbstractAudioContext::AutoLocker locker(context());
        m_mixBus = AudioBus::create(channelCount, ProcessingSizeInFrames);
        m_source->setAudioFormat(channelCount, context()->sampleRate());
    }
}

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

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

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

MediaStreamAudioDestinationNode* MediaStreamAudioDestinationNode::create(AbstractAudioContext& context, size_t numberOfChannels)
{
    return new MediaStreamAudioDestinationNode(context, numberOfChannels);
}

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

} // namespace blink