1/* 2 * Copyright (C) 2011 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 * 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 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. 16 * 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. 27 */ 28 29#ifndef DynamicsCompressorKernel_h 30#define DynamicsCompressorKernel_h 31 32#include "AudioArray.h" 33#include <memory> 34 35namespace WebCore { 36 37class DynamicsCompressorKernel { 38public: 39 DynamicsCompressorKernel(float sampleRate, unsigned numberOfChannels); 40 41 void setNumberOfChannels(unsigned); 42 43 // Performs stereo-linked compression. 44 void process(float* sourceChannels[], 45 float* destinationChannels[], 46 unsigned numberOfChannels, 47 unsigned framesToProcess, 48 49 float dbThreshold, 50 float dbKnee, 51 float ratio, 52 float attackTime, 53 float releaseTime, 54 float preDelayTime, 55 float dbPostGain, 56 float effectBlend, 57 58 float releaseZone1, 59 float releaseZone2, 60 float releaseZone3, 61 float releaseZone4 62 ); 63 64 void reset(); 65 66 unsigned latencyFrames() const { return m_lastPreDelayFrames; } 67 68 float sampleRate() const { return m_sampleRate; } 69 70 float meteringGain() const { return m_meteringGain; } 71 72protected: 73 float m_sampleRate; 74 75 float m_detectorAverage; 76 float m_compressorGain; 77 78 // Metering 79 float m_meteringReleaseK; 80 float m_meteringGain; 81 82 // Lookahead section. 83 enum { MaxPreDelayFrames = 1024 }; 84 enum { MaxPreDelayFramesMask = MaxPreDelayFrames - 1 }; 85 enum { DefaultPreDelayFrames = 256 }; // setPreDelayTime() will override this initial value 86 unsigned m_lastPreDelayFrames; 87 void setPreDelayTime(float); 88 89 Vector<std::unique_ptr<AudioFloatArray>> m_preDelayBuffers; 90 int m_preDelayReadIndex; 91 int m_preDelayWriteIndex; 92 93 float m_maxAttackCompressionDiffDb; 94 95 // Static compression curve. 96 float kneeCurve(float x, float k); 97 float saturate(float x, float k); 98 float slopeAt(float x, float k); 99 float kAtSlope(float desiredSlope); 100 101 float updateStaticCurveParameters(float dbThreshold, float dbKnee, float ratio); 102 103 // Amount of input change in dB required for 1 dB of output change. 104 // This applies to the portion of the curve above m_kneeThresholdDb (see below). 105 float m_ratio; 106 float m_slope; // Inverse ratio. 107 108 // The input to output change below the threshold is linear 1:1. 109 float m_linearThreshold; 110 float m_dbThreshold; 111 112 // m_dbKnee is the number of dB above the threshold before we enter the "ratio" portion of the curve. 113 // m_kneeThresholdDb = m_dbThreshold + m_dbKnee 114 // The portion between m_dbThreshold and m_kneeThresholdDb is the "soft knee" portion of the curve 115 // which transitions smoothly from the linear portion to the ratio portion. 116 float m_dbKnee; 117 float m_kneeThreshold; 118 float m_kneeThresholdDb; 119 float m_ykneeThresholdDb; 120 121 // Internal parameter for the knee portion of the curve. 122 float m_K; 123}; 124 125} // namespace WebCore 126 127#endif // DynamicsCompressorKernel_h 128