Source/WebCore/Modules/webaudio/AudioDestinationNode.cpp

/*
 * Copyright (C) 2010, Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *    notice, this list of conditions and the following disclaimer in the
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 *
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 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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#include "config.h"

#if ENABLE(WEB_AUDIO)

#include "AudioDestinationNode.h"

#include "AudioContext.h"
#include "AudioNodeInput.h"
#include "AudioNodeOutput.h"
#include "AudioUtilities.h"
#include "DenormalDisabler.h"
#include <wtf/IsoMallocInlines.h>

namespace WebCore {
    
WTF_MAKE_ISO_ALLOCATED_IMPL(AudioDestinationNode);

AudioDestinationNode::AudioDestinationNode(AudioContext& context, float sampleRate)
    : AudioNode(context, sampleRate)
    , m_currentSampleFrame(0)
    , m_isSilent(true)
    , m_isEffectivelyPlayingAudio(false)
    , m_muted(false)
{
    setNodeType(NodeTypeDestination);
    addInput(makeUnique<AudioNodeInput>(this));
}

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

void AudioDestinationNode::render(AudioBus*, AudioBus* destinationBus, size_t numberOfFrames)
{
    // We don't want denormals slowing down any of the audio processing
    // since they can very seriously hurt performance.
    // This will take care of all AudioNodes because they all process within this scope.
    DenormalDisabler denormalDisabler;
    
    context().setAudioThread(Thread::current());
    
    if (!context().isInitialized()) {
        destinationBus->zero();
        setIsSilent(true);
        return;
    }

    ASSERT(numberOfFrames);
    if (!numberOfFrames) {
        destinationBus->zero();
        setIsSilent(true);
        return;
    }

    // Let the context take care of any business at the start of each render quantum.
    context().handlePreRenderTasks();

    // This will cause the node(s) connected to us to process, which in turn will pull on their input(s),
    // all the way backwards through the rendering graph.
    AudioBus* renderedBus = input(0)->pull(destinationBus, numberOfFrames);
    
    if (!renderedBus)
        destinationBus->zero();
    else if (renderedBus != destinationBus) {
        // in-place processing was not possible - so copy
        destinationBus->copyFrom(*renderedBus);
    }

    // Process nodes which need a little extra help because they are not connected to anything, but still need to process.
    context().processAutomaticPullNodes(numberOfFrames);

    // Let the context take care of any business at the end of each render quantum.
    context().handlePostRenderTasks();
    
    // Advance current sample-frame.
    m_currentSampleFrame += numberOfFrames;

    setIsSilent(destinationBus->isSilent());

    // The reason we are handling mute after the call to setIsSilent() is because the muted state does
    // not affect the audio destination node's effective playing state.
    if (m_muted)
        destinationBus->zero();
}

void AudioDestinationNode::isPlayingDidChange()
{
    updateIsEffectivelyPlayingAudio();
}

void AudioDestinationNode::setIsSilent(bool isSilent)
{
    if (m_isSilent == isSilent)
        return;

    m_isSilent = isSilent;
    updateIsEffectivelyPlayingAudio();
}

void AudioDestinationNode::updateIsEffectivelyPlayingAudio()
{
    bool isEffectivelyPlayingAudio = isPlaying() && !m_isSilent;
    if (m_isEffectivelyPlayingAudio == isEffectivelyPlayingAudio)
        return;

    m_isEffectivelyPlayingAudio = isEffectivelyPlayingAudio;
    context().isPlayingAudioDidChange();
}

} // namespace WebCore

#endif // ENABLE(WEB_AUDIO)