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29 #include "AudioGainNode.h"
32 #include "AudioNodeInput.h"
33 #include "AudioNodeOutput.h"
37 AudioGainNode::AudioGainNode(AudioContext* context, double sampleRate)
38 : AudioNode(context, sampleRate)
40 , m_sampleAccurateGainValues(AudioNode::ProcessingSizeInFrames) // FIXME: can probably share temp buffer in context
42 m_gain = AudioGain::create("gain", 1.0, 0.0, 1.0);
43 m_gain->setContext(context);
45 addInput(adoptPtr(new AudioNodeInput(this)));
46 addOutput(adoptPtr(new AudioNodeOutput(this, 1)));
48 setType(NodeTypeGain);
53 void AudioGainNode::process(size_t framesToProcess)
55 // FIXME: for some cases there is a nice optimization to avoid processing here, and let the gain change
56 // happen in the summing junction input of the AudioNode we're connected to.
57 // Then we can avoid all of the following:
59 AudioBus* outputBus = output(0)->bus();
62 // The realtime thread can't block on this lock, so we call tryLock() instead.
63 if (m_processLock.tryLock()) {
64 if (!isInitialized() || !input(0)->isConnected())
67 AudioBus* inputBus = input(0)->bus();
69 if (gain()->hasTimelineValues()) {
70 // Apply sample-accurate gain scaling for precise envelopes, grain windows, etc.
71 ASSERT(framesToProcess <= m_sampleAccurateGainValues.size());
72 if (framesToProcess <= m_sampleAccurateGainValues.size()) {
73 float* gainValues = m_sampleAccurateGainValues.data();
74 gain()->calculateSampleAccurateValues(gainValues, framesToProcess);
75 outputBus->copyWithSampleAccurateGainValuesFrom(*inputBus, gainValues, framesToProcess);
78 // Apply the gain with de-zippering into the output bus.
79 outputBus->copyWithGainFrom(*inputBus, &m_lastGain, gain()->value());
83 m_processLock.unlock();
85 // Too bad - the tryLock() failed. We must be in the middle of re-connecting and were already outputting silence anyway...
90 void AudioGainNode::reset()
92 // Snap directly to desired gain.
93 m_lastGain = gain()->value();
96 // FIXME: this can go away when we do mixing with gain directly in summing junction of AudioNodeInput
98 // As soon as we know the channel count of our input, we can lazily initialize.
99 // Sometimes this may be called more than once with different channel counts, in which case we must safely
100 // uninitialize and then re-initialize with the new channel count.
101 void AudioGainNode::checkNumberOfChannelsForInput(AudioNodeInput* input)
103 ASSERT(input && input == this->input(0));
104 if (input != this->input(0))
107 unsigned numberOfChannels = input->numberOfChannels();
109 if (isInitialized() && numberOfChannels != output(0)->numberOfChannels()) {
110 // We're already initialized but the channel count has changed.
111 // We need to be careful since we may be actively processing right now, so synchronize with process().
112 MutexLocker locker(m_processLock);
116 if (!isInitialized()) {
117 // This will propagate the channel count to any nodes connected further downstream in the graph.
118 output(0)->setNumberOfChannels(numberOfChannels);
123 } // namespace WebCore
125 #endif // ENABLE(WEB_AUDIO)