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 #ifndef GainNode_h 26 #define GainNode_h 27 28 #include "modules/webaudio/AudioNode.h" 29 #include "modules/webaudio/AudioParam.h" 30 #include "wtf/PassRefPtr.h" 31 #include "wtf/Threading.h" 32 33 namespace WebCore { 34 35 class AudioContext; 36 37 // GainNode is an AudioNode with one input and one output which applies a gain (volume) change to the audio signal. 38 // De-zippering (smoothing) is applied when the gain value is changed dynamically. 39 40 class GainNode : public AudioNode { 41 public: 42 static PassRefPtr<GainNode> create(AudioContext* context, float sampleRate) 43 { 44 return adoptRef(new GainNode(context, sampleRate)); 45 } 46 47 // AudioNode 48 virtual void process(size_t framesToProcess); 49 virtual void reset(); 50 51 // Called in the main thread when the number of channels for the input may have changed. 52 virtual void checkNumberOfChannelsForInput(AudioNodeInput*); 53 54 // JavaScript interface 55 AudioParam* gain() { return m_gain.get(); } 56 57 private: 58 virtual double tailTime() const OVERRIDE { return 0; } 59 virtual double latencyTime() const OVERRIDE { return 0; } 60 61 GainNode(AudioContext*, float sampleRate); 62 63 float m_lastGain; // for de-zippering 64 RefPtr<AudioParam> m_gain; 65 66 AudioFloatArray m_sampleAccurateGainValues; 67 }; 68 69 } // namespace WebCore 70 71 #endif // GainNode_h 72
