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/*
* 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
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 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
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#if ENABLE(WEB_AUDIO)
#include "AudioGainNode.h"
#include "AudioBus.h"
#include "AudioNodeInput.h"
#include "AudioNodeOutput.h"
namespace WebCore {
AudioGainNode::AudioGainNode(AudioContext* context, double sampleRate)
: AudioNode(context, sampleRate)
, m_lastGain(1.0)
{
m_gain = AudioGain::create("gain", 1.0, 0.0, 1.0);
addInput(adoptPtr(new AudioNodeInput(this)));
addOutput(adoptPtr(new AudioNodeOutput(this, 1)));
setType(NodeTypeGain);
initialize();
}
void AudioGainNode::process(size_t /*framesToProcess*/)
{
// FIXME: there is a nice optimization to avoid processing here, and let the gain change
// happen in the summing junction input of the AudioNode we're connected to.
// Then we can avoid all of the following:
AudioBus* outputBus = output(0)->bus();
ASSERT(outputBus);
// The realtime thread can't block on this lock, so we call tryLock() instead.
if (m_processLock.tryLock()) {
if (!isInitialized() || !input(0)->isConnected())
outputBus->zero();
else {
AudioBus* inputBus = input(0)->bus();
// Apply the gain with de-zippering into the output bus.
outputBus->copyWithGainFrom(*inputBus, &m_lastGain, gain()->value());
}
m_processLock.unlock();
} else {
// Too bad - the tryLock() failed. We must be in the middle of re-connecting and were already outputting silence anyway...
outputBus->zero();
}
}
void AudioGainNode::reset()
{
// Snap directly to desired gain.
m_lastGain = gain()->value();
}
// FIXME: this can go away when we do mixing with gain directly in summing junction of AudioNodeInput
//
// As soon as we know the channel count of our input, we can lazily initialize.
// Sometimes this may be called more than once with different channel counts, in which case we must safely
// uninitialize and then re-initialize with the new channel count.
void AudioGainNode::checkNumberOfChannelsForInput(AudioNodeInput* input)
{
ASSERT(input && input == this->input(0));
if (input != this->input(0))
return;
unsigned numberOfChannels = input->numberOfChannels();
if (isInitialized() && numberOfChannels != output(0)->numberOfChannels()) {
// We're already initialized but the channel count has changed.
// We need to be careful since we may be actively processing right now, so synchronize with process().
MutexLocker locker(m_processLock);
uninitialize();
}
if (!isInitialized()) {
// This will propagate the channel count to any nodes connected further downstream in the graph.
output(0)->setNumberOfChannels(numberOfChannels);
initialize();
}
}
} // namespace WebCore
#endif // ENABLE(WEB_AUDIO)
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