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33 #include "platform/audio/DynamicsCompressor.h"
35 #include "platform/audio/AudioBus.h"
36 #include "platform/audio/AudioUtilities.h"
37 #include "wtf/MathExtras.h"
41 using namespace AudioUtilities;
43 DynamicsCompressor::DynamicsCompressor(float sampleRate, unsigned numberOfChannels)
44 : m_numberOfChannels(numberOfChannels)
45 , m_sampleRate(sampleRate)
46 , m_compressor(sampleRate, numberOfChannels)
48 // Uninitialized state - for parameter recalculation.
49 m_lastFilterStageRatio = -1;
51 m_lastFilterStageGain = -1;
53 setNumberOfChannels(numberOfChannels);
54 initializeParameters();
57 void DynamicsCompressor::setParameterValue(unsigned parameterID, float value)
59 ASSERT(parameterID < ParamLast);
60 if (parameterID < ParamLast)
61 m_parameters[parameterID] = value;
64 void DynamicsCompressor::initializeParameters()
66 // Initializes compressor to default values.
68 m_parameters[ParamThreshold] = -24; // dB
69 m_parameters[ParamKnee] = 30; // dB
70 m_parameters[ParamRatio] = 12; // unit-less
71 m_parameters[ParamAttack] = 0.003f; // seconds
72 m_parameters[ParamRelease] = 0.250f; // seconds
73 m_parameters[ParamPreDelay] = 0.006f; // seconds
75 // Release zone values 0 -> 1.
76 m_parameters[ParamReleaseZone1] = 0.09f;
77 m_parameters[ParamReleaseZone2] = 0.16f;
78 m_parameters[ParamReleaseZone3] = 0.42f;
79 m_parameters[ParamReleaseZone4] = 0.98f;
81 m_parameters[ParamFilterStageGain] = 4.4f; // dB
82 m_parameters[ParamFilterStageRatio] = 2;
83 m_parameters[ParamFilterAnchor] = 15000 / nyquist();
85 m_parameters[ParamPostGain] = 0; // dB
86 m_parameters[ParamReduction] = 0; // dB
88 // Linear crossfade (0 -> 1).
89 m_parameters[ParamEffectBlend] = 1;
92 float DynamicsCompressor::parameterValue(unsigned parameterID)
94 ASSERT(parameterID < ParamLast);
95 return m_parameters[parameterID];
98 void DynamicsCompressor::process(const AudioBus* sourceBus, AudioBus* destinationBus, unsigned framesToProcess)
100 // Though numberOfChannels is retrived from destinationBus, we still name it numberOfChannels instead of numberOfDestinationChannels.
101 // It's because we internally match sourceChannels's size to destinationBus by channel up/down mix. Thus we need numberOfChannels
102 // to do the loop work for both m_sourceChannels and m_destinationChannels.
104 unsigned numberOfChannels = destinationBus->numberOfChannels();
105 unsigned numberOfSourceChannels = sourceBus->numberOfChannels();
107 ASSERT(numberOfChannels == m_numberOfChannels && numberOfSourceChannels);
109 if (numberOfChannels != m_numberOfChannels || !numberOfSourceChannels) {
110 destinationBus->zero();
114 switch (numberOfChannels) {
116 m_sourceChannels[0] = sourceBus->channel(0)->data();
118 if (numberOfSourceChannels > 1)
119 m_sourceChannels[1] = sourceBus->channel(1)->data();
121 // Simply duplicate mono channel input data to right channel for stereo processing.
122 m_sourceChannels[1] = m_sourceChannels[0];
126 // FIXME : support other number of channels.
127 ASSERT_NOT_REACHED();
128 destinationBus->zero();
132 for (unsigned i = 0; i < numberOfChannels; ++i)
133 m_destinationChannels[i] = destinationBus->channel(i)->mutableData();
135 float filterStageGain = parameterValue(ParamFilterStageGain);
136 float filterStageRatio = parameterValue(ParamFilterStageRatio);
137 float anchor = parameterValue(ParamFilterAnchor);
139 if (filterStageGain != m_lastFilterStageGain || filterStageRatio != m_lastFilterStageRatio || anchor != m_lastAnchor) {
140 m_lastFilterStageGain = filterStageGain;
141 m_lastFilterStageRatio = filterStageRatio;
142 m_lastAnchor = anchor;
146 float dbThreshold = parameterValue(ParamThreshold);
147 float dbKnee = parameterValue(ParamKnee);
148 float ratio = parameterValue(ParamRatio);
149 float attackTime = parameterValue(ParamAttack);
150 float releaseTime = parameterValue(ParamRelease);
151 float preDelayTime = parameterValue(ParamPreDelay);
153 // This is effectively a master volume on the compressed signal (pre-blending).
154 float dbPostGain = parameterValue(ParamPostGain);
156 // Linear blending value from dry to completely processed (0 -> 1)
157 // 0 means the signal is completely unprocessed.
158 // 1 mixes in only the compressed signal.
159 float effectBlend = parameterValue(ParamEffectBlend);
161 float releaseZone1 = parameterValue(ParamReleaseZone1);
162 float releaseZone2 = parameterValue(ParamReleaseZone2);
163 float releaseZone3 = parameterValue(ParamReleaseZone3);
164 float releaseZone4 = parameterValue(ParamReleaseZone4);
166 // Apply compression to the source signal.
167 m_compressor.process(m_sourceChannels.get(),
168 m_destinationChannels.get(),
187 // Update the compression amount.
188 setParameterValue(ParamReduction, m_compressor.meteringGain());
192 void DynamicsCompressor::reset()
194 m_lastFilterStageRatio = -1; // for recalc
196 m_lastFilterStageGain = -1;
198 m_compressor.reset();
201 void DynamicsCompressor::setNumberOfChannels(unsigned numberOfChannels)
203 m_sourceChannels = adoptArrayPtr(new const float* [numberOfChannels]);
204 m_destinationChannels = adoptArrayPtr(new float* [numberOfChannels]);
206 m_compressor.setNumberOfChannels(numberOfChannels);
207 m_numberOfChannels = numberOfChannels;
210 } // namespace WebCore
212 #endif // ENABLE(WEB_AUDIO)