2 * Copyright (C) 2011 Google Inc. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
14 * its contributors may be used to endorse or promote products derived
15 * from this software without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 #ifndef DynamicsCompressor_h
30 #define DynamicsCompressor_h
32 #include "AudioArray.h"
33 #include "DynamicsCompressorKernel.h"
40 // DynamicsCompressor implements a flexible audio dynamics compression effect such as
41 // is commonly used in musical production and game audio. It lowers the volume
42 // of the loudest parts of the signal and raises the volume of the softest parts,
43 // making the sound richer, fuller, and more controlled.
45 class DynamicsCompressor {
59 ParamFilterStageRatio,
65 DynamicsCompressor(bool isStereo, double sampleRate);
67 void process(AudioBus* sourceBus, AudioBus* destinationBus, unsigned framesToProcess);
70 double parameterValue(unsigned parameterID);
72 bool isStereo() const { return m_isStereo; }
73 double sampleRate() const { return m_sampleRate; }
74 double nyquist() const { return 0.5 * m_sampleRate; }
77 // m_parameters holds the tweakable compressor parameters.
78 // FIXME: expose some of the most important ones (such as threshold, attack, release)
79 // as DynamicsCompressorNode attributes.
80 double m_parameters[ParamLast];
81 void initializeParameters();
86 // Emphasis filter controls.
87 float m_lastFilterStageRatio;
89 float m_lastFilterStageGain;
92 ZeroPole m_preFilter[4];
93 ZeroPole m_preFilterR[4];
94 ZeroPole m_postFilter[4];
95 ZeroPole m_postFilterR[4];
97 void setEmphasisStageParameters(unsigned stageIndex, float gain, float normalizedFrequency /* 0 -> 1 */);
98 void setEmphasisParameters(float gain, float anchorFreq, float filterStageRatio);
100 // The core compressor.
101 DynamicsCompressorKernel m_compressor;
104 } // namespace WebCore
106 #endif // DynamicsCompressor_h