1 /* 2 * Copyright (C) 2010, Google Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY 14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 15 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 16 * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY 17 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 18 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 19 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON 20 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 22 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 23 */ 24 25 #include "config.h" 26 27 #if ENABLE(WEB_AUDIO) 28 29 #include "AudioGainNode.h" 30 31 #include "AudioBus.h" 32 #include "AudioNodeInput.h" 33 #include "AudioNodeOutput.h" 34 35 namespace WebCore { 36 37 AudioGainNode::AudioGainNode(AudioContext* context, double sampleRate) 38 : AudioNode(context, sampleRate) 39 , m_lastGain(1.0) 40 { 41 m_gain = AudioGain::create("gain", 1.0, 0.0, 1.0); 42 43 addInput(adoptPtr(new AudioNodeInput(this))); 44 addOutput(adoptPtr(new AudioNodeOutput(this, 1))); 45 46 setType(NodeTypeGain); 47 48 initialize(); 49 } 50 51 void AudioGainNode::process(size_t /*framesToProcess*/) 52 { 53 // FIXME: there is a nice optimization to avoid processing here, and let the gain change 54 // happen in the summing junction input of the AudioNode we're connected to. 55 // Then we can avoid all of the following: 56 57 AudioBus* outputBus = output(0)->bus(); 58 ASSERT(outputBus); 59 60 // The realtime thread can't block on this lock, so we call tryLock() instead. 61 if (m_processLock.tryLock()) { 62 if (!isInitialized() || !input(0)->isConnected()) 63 outputBus->zero(); 64 else { 65 AudioBus* inputBus = input(0)->bus(); 66 67 // Apply the gain with de-zippering into the output bus. 68 outputBus->copyWithGainFrom(*inputBus, &m_lastGain, gain()->value()); 69 } 70 71 m_processLock.unlock(); 72 } else { 73 // Too bad - the tryLock() failed. We must be in the middle of re-connecting and were already outputting silence anyway... 74 outputBus->zero(); 75 } 76 } 77 78 void AudioGainNode::reset() 79 { 80 // Snap directly to desired gain. 81 m_lastGain = gain()->value(); 82 } 83 84 // FIXME: this can go away when we do mixing with gain directly in summing junction of AudioNodeInput 85 // 86 // As soon as we know the channel count of our input, we can lazily initialize. 87 // Sometimes this may be called more than once with different channel counts, in which case we must safely 88 // uninitialize and then re-initialize with the new channel count. 89 void AudioGainNode::checkNumberOfChannelsForInput(AudioNodeInput* input) 90 { 91 ASSERT(input && input == this->input(0)); 92 if (input != this->input(0)) 93 return; 94 95 unsigned numberOfChannels = input->numberOfChannels(); 96 97 if (isInitialized() && numberOfChannels != output(0)->numberOfChannels()) { 98 // We're already initialized but the channel count has changed. 99 // We need to be careful since we may be actively processing right now, so synchronize with process(). 100 MutexLocker locker(m_processLock); 101 uninitialize(); 102 } 103 104 if (!isInitialized()) { 105 // This will propagate the channel count to any nodes connected further downstream in the graph. 106 output(0)->setNumberOfChannels(numberOfChannels); 107 initialize(); 108 } 109 } 110 111 } // namespace WebCore 112 113 #endif // ENABLE(WEB_AUDIO) 114