Source/WebCore/Modules/webaudio/ChannelSplitterNode.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.
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 *    notice, this list of conditions and the following disclaimer in the
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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
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 * 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 "ChannelSplitterNode.h"

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

namespace WebCore {

WTF_MAKE_ISO_ALLOCATED_IMPL(ChannelSplitterNode);
    
RefPtr<ChannelSplitterNode> ChannelSplitterNode::create(BaseAudioContext& context, float sampleRate, unsigned numberOfOutputs)
{
    if (!numberOfOutputs || numberOfOutputs > AudioContext::maxNumberOfChannels())
        return nullptr;

    return adoptRef(*new ChannelSplitterNode(context, sampleRate, numberOfOutputs));      
}

ChannelSplitterNode::ChannelSplitterNode(BaseAudioContext& context, float sampleRate, unsigned numberOfOutputs)
    : AudioNode(context, sampleRate)
{
    setNodeType(NodeTypeChannelSplitter);

    addInput(makeUnique<AudioNodeInput>(this));

    // Create a fixed number of outputs (able to handle the maximum number of channels fed to an input).
    for (unsigned i = 0; i < numberOfOutputs; ++i)
        addOutput(makeUnique<AudioNodeOutput>(this, 1));
    
    initialize();
}

void ChannelSplitterNode::process(size_t framesToProcess)
{
    AudioBus* source = input(0)->bus();
    ASSERT(source);
    ASSERT_UNUSED(framesToProcess, framesToProcess == source->length());
    
    unsigned numberOfSourceChannels = source->numberOfChannels();
    
    for (unsigned i = 0; i < numberOfOutputs(); ++i) {
        AudioBus* destination = output(i)->bus();
        ASSERT(destination);
        
        if (i < numberOfSourceChannels) {
            // Split the channel out if it exists in the source.
            // It would be nice to avoid the copy and simply pass along pointers, but this becomes extremely difficult with fanout and fanin.
            destination->channel(0)->copyFrom(source->channel(i));
        } else if (output(i)->renderingFanOutCount() > 0) {
            // Only bother zeroing out the destination if it's connected to anything
            destination->zero();
        }
    }
}

void ChannelSplitterNode::reset()
{
}

} // namespace WebCore

#endif // ENABLE(WEB_AUDIO)