Source/modules/webaudio/ChannelMergerNode.cpp

/*
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#include "config.h"
#if ENABLE(WEB_AUDIO)
#include "modules/webaudio/ChannelMergerNode.h"

#include "bindings/core/v8/ExceptionMessages.h"
#include "bindings/core/v8/ExceptionState.h"
#include "core/dom/ExceptionCode.h"
#include "core/dom/ExecutionContext.h"
#include "modules/webaudio/AbstractAudioContext.h"
#include "modules/webaudio/AudioNodeInput.h"
#include "modules/webaudio/AudioNodeOutput.h"


namespace blink {

ChannelMergerHandler::ChannelMergerHandler(AudioNode& node, float sampleRate, unsigned numberOfInputs)
    : AudioHandler(NodeTypeChannelMerger, node, sampleRate)
{
    // These properties are fixed for the node and cannot be changed by user.
    m_channelCount = 1;
    m_channelCountMode = Explicit;

    // Create the requested number of inputs.
    for (unsigned i = 0; i < numberOfInputs; ++i)
        addInput();

    // Create the output with the requested number of channels.
    addOutput(numberOfInputs);

    initialize();
}

PassRefPtr<ChannelMergerHandler> ChannelMergerHandler::create(AudioNode& node, float sampleRate, unsigned numberOfInputs)
{
    return adoptRef(new ChannelMergerHandler(node, sampleRate, numberOfInputs));
}

void ChannelMergerHandler::process(size_t framesToProcess)
{
    AudioNodeOutput& output = this->output(0);
    ASSERT_UNUSED(framesToProcess, framesToProcess == output.bus()->length());

    unsigned numberOfOutputChannels = output.numberOfChannels();
    ASSERT(numberOfInputs() == numberOfOutputChannels);

    // Merge multiple inputs into one output.
    for (unsigned i = 0; i < numberOfOutputChannels; ++i) {
        AudioNodeInput& input = this->input(i);
        ASSERT(input.numberOfChannels() == 1);
        AudioChannel* outputChannel = output.bus()->channel(i);
        if (input.isConnected()) {

            // The mixing rules will be applied so multiple channels are down-
            // mixed to mono (when the mixing rule is defined). Note that only
            // the first channel will be taken for the undefined input channel
            // layout.
            //
            // See: http://webaudio.github.io/web-audio-api/#channel-up-mixing-and-down-mixing
            AudioChannel* inputChannel = input.bus()->channel(0);
            outputChannel->copyFrom(inputChannel);

        } else {
            // If input is unconnected, fill zeros in the channel.
            outputChannel->zero();
        }
    }
}

void ChannelMergerHandler::setChannelCount(unsigned long channelCount, ExceptionState& exceptionState)
{
    ASSERT(isMainThread());
    AbstractAudioContext::AutoLocker locker(context());

    // channelCount must be 1.
    if (channelCount != 1) {
        exceptionState.throwDOMException(
            InvalidStateError,
            "ChannelMerger: channelCount cannot be changed from 1");
    }
}

void ChannelMergerHandler::setChannelCountMode(const String& mode, ExceptionState& exceptionState)
{
    ASSERT(isMainThread());
    AbstractAudioContext::AutoLocker locker(context());

    // channcelCountMode must be 'explicit'.
    if (mode != "explicit") {
        exceptionState.throwDOMException(
            InvalidStateError,
            "ChannelMerger: channelCountMode cannot be changed from 'explicit'");
    }
}

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

ChannelMergerNode::ChannelMergerNode(AbstractAudioContext& context, float sampleRate, unsigned numberOfInputs)
    : AudioNode(context)
{
    setHandler(ChannelMergerHandler::create(*this, sampleRate, numberOfInputs));
}

ChannelMergerNode* ChannelMergerNode::create(AbstractAudioContext& context, float sampleRate, unsigned numberOfInputs)
{
    if (!numberOfInputs || numberOfInputs > AbstractAudioContext::maxNumberOfChannels())
        return nullptr;
    return new ChannelMergerNode(context, sampleRate, numberOfInputs);
}

} // namespace blink

#endif // ENABLE(WEB_AUDIO)