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 DynamicsCompressor_h
30#define DynamicsCompressor_h
31
32#include "AudioArray.h"
33#include "DynamicsCompressorKernel.h"
34#include "ZeroPole.h"
35#include <memory>
36
37namespace WebCore {
38
39class AudioBus;
40
41// DynamicsCompressor implements a flexible audio dynamics compression effect such as
42// is commonly used in musical production and game audio. It lowers the volume
43// of the loudest parts of the signal and raises the volume of the softest parts,
44// making the sound richer, fuller, and more controlled.
45
46class DynamicsCompressor {
47public:
48    enum {
49        ParamThreshold,
50        ParamKnee,
51        ParamRatio,
52        ParamAttack,
53        ParamRelease,
54        ParamPreDelay,
55        ParamReleaseZone1,
56        ParamReleaseZone2,
57        ParamReleaseZone3,
58        ParamReleaseZone4,
59        ParamPostGain,
60        ParamFilterStageGain,
61        ParamFilterStageRatio,
62        ParamFilterAnchor,
63        ParamEffectBlend,
64        ParamReduction,
65        ParamLast
66    };
67
68    DynamicsCompressor(float sampleRate, unsigned numberOfChannels);
69
70    void process(const AudioBus* sourceBus, AudioBus* destinationBus, unsigned framesToProcess);
71    void reset();
72    void setNumberOfChannels(unsigned);
73
74    void setParameterValue(unsigned parameterID, float value);
75    float parameterValue(unsigned parameterID);
76
77    float sampleRate() const { return m_sampleRate; }
78    float nyquist() const { return m_sampleRate / 2; }
79
80    double tailTime() const { return 0; }
81    double latencyTime() const { return m_compressor.latencyFrames() / static_cast<double>(sampleRate()); }
82
83protected:
84    unsigned m_numberOfChannels;
85
86    // m_parameters holds the tweakable compressor parameters.
87    float m_parameters[ParamLast];
88    void initializeParameters();
89
90    float m_sampleRate;
91
92    // Emphasis filter controls.
93    float m_lastFilterStageRatio;
94    float m_lastAnchor;
95    float m_lastFilterStageGain;
96
97    typedef struct {
98        ZeroPole filters[4];
99    } ZeroPoleFilterPack4;
100
101    // Per-channel emphasis filters.
102    Vector<std::unique_ptr<ZeroPoleFilterPack4>> m_preFilterPacks;
103    Vector<std::unique_ptr<ZeroPoleFilterPack4>> m_postFilterPacks;
104
105    std::unique_ptr<const float*[]> m_sourceChannels;
106    std::unique_ptr<float*[]> m_destinationChannels;
107
108    void setEmphasisStageParameters(unsigned stageIndex, float gain, float normalizedFrequency /* 0 -> 1 */);
109    void setEmphasisParameters(float gain, float anchorFreq, float filterStageRatio);
110
111    // The core compressor.
112    DynamicsCompressorKernel m_compressor;
113};
114
115} // namespace WebCore
116
117#endif // DynamicsCompressor_h
118