AudioDestinationNode.cpp   [plain text]


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#include "config.h"

#if ENABLE(WEB_AUDIO)

#include "AudioDestinationNode.h"

#include "AudioBus.h"
#include "AudioContext.h"
#include "AudioNodeInput.h"
#include "AudioNodeOutput.h"
#include "AudioUtilities.h"
#include "DenormalDisabler.h"

namespace WebCore {
    
AudioDestinationNode::AudioDestinationNode(AudioContext* context, float sampleRate)
    : AudioNode(context, sampleRate)
    , m_currentSampleFrame(0)
{
    addInput(adoptPtr(new AudioNodeInput(this)));
    
    setNodeType(NodeTypeDestination);
}

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

// The audio hardware calls us back here to gets its input stream.
void AudioDestinationNode::provideInput(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()->isRunnable()) {
        destinationBus->zero();
        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;
}

} // namespace WebCore

#endif // ENABLE(WEB_AUDIO)