root/Source/modules/webaudio/AudioDestinationNode.cpp

DEFINITIONS

1. m_currentSampleFrame
2. render

/*
 * 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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 *
 * 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
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#include "config.h"

#if ENABLE(WEB_AUDIO)

#include "modules/webaudio/AudioDestinationNode.h"

#include "platform/audio/AudioUtilities.h"
#include "platform/audio/DenormalDisabler.h"
#include "modules/webaudio/AudioContext.h"
#include "modules/webaudio/AudioNodeInput.h"
#include "modules/webaudio/AudioNodeOutput.h"

namespace WebCore {

AudioDestinationNode::AudioDestinationNode(AudioContext* context, float sampleRate)
    : AudioNode(context, sampleRate)
    , m_currentSampleFrame(0)
{
    ScriptWrappable::init(this);
    addInput(adoptPtr(new AudioNodeInput(this)));

    setNodeType(NodeTypeDestination);
}

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

void AudioDestinationNode::render(AudioBus* sourceBus, 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(currentThread());

    if (!context()->isInitialized()) {
        destinationBus->zero();
        return;
    }

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

    // Prepare the local audio input provider for this render quantum.
    if (sourceBus)
        m_localAudioInputProvider.set(sourceBus);

    // 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;
}

} // namespace WebCore

#endif // ENABLE(WEB_AUDIO)