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/*
* Copyright (C) 2011 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#if ENABLE(WEB_AUDIO)
#include "DynamicsCompressor.h"
#include "AudioBus.h"
#include "AudioUtilities.h"
#include <wtf/MathExtras.h>
namespace WebCore {
using namespace AudioUtilities;
DynamicsCompressor::DynamicsCompressor(bool isStereo, float sampleRate)
: m_isStereo(isStereo)
, m_sampleRate(sampleRate)
, m_compressor(sampleRate)
{
// Uninitialized state - for parameter recalculation.
m_lastFilterStageRatio = -1;
m_lastAnchor = -1;
m_lastFilterStageGain = -1;
initializeParameters();
}
void DynamicsCompressor::initializeParameters()
{
// Initializes compressor to default values.
m_parameters[ParamThreshold] = -24; // dB
m_parameters[ParamHeadroom] = 21; // dB
m_parameters[ParamAttack] = 0.003f; // seconds
m_parameters[ParamRelease] = 0.250f; // seconds
m_parameters[ParamPreDelay] = 0.006f; // seconds
// Release zone values 0 -> 1.
m_parameters[ParamReleaseZone1] = 0.09f;
m_parameters[ParamReleaseZone2] = 0.16f;
m_parameters[ParamReleaseZone3] = 0.42f;
m_parameters[ParamReleaseZone4] = 0.98f;
m_parameters[ParamFilterStageGain] = 4.4f; // dB
m_parameters[ParamFilterStageRatio] = 2;
m_parameters[ParamFilterAnchor] = 15000 / nyquist();
m_parameters[ParamPostGain] = 0; // dB
// Linear crossfade (0 -> 1).
m_parameters[ParamEffectBlend] = 1;
}
float DynamicsCompressor::parameterValue(unsigned parameterID)
{
ASSERT(parameterID < ParamLast);
return m_parameters[parameterID];
}
void DynamicsCompressor::setEmphasisStageParameters(unsigned stageIndex, float gain, float normalizedFrequency /* 0 -> 1 */)
{
float gk = 1 - gain / 20;
float f1 = normalizedFrequency * gk;
float f2 = normalizedFrequency / gk;
float r1 = expf(-f1 * piFloat);
float r2 = expf(-f2 * piFloat);
// Set pre-filter zero and pole to create an emphasis filter.
m_preFilter[stageIndex].setZero(r1);
m_preFilter[stageIndex].setPole(r2);
m_preFilterR[stageIndex].setZero(r1);
m_preFilterR[stageIndex].setPole(r2);
// Set post-filter with zero and pole reversed to create the de-emphasis filter.
// If there were no compressor kernel in between, they would cancel each other out (allpass filter).
m_postFilter[stageIndex].setZero(r2);
m_postFilter[stageIndex].setPole(r1);
m_postFilterR[stageIndex].setZero(r2);
m_postFilterR[stageIndex].setPole(r1);
}
void DynamicsCompressor::setEmphasisParameters(float gain, float anchorFreq, float filterStageRatio)
{
setEmphasisStageParameters(0, gain, anchorFreq);
setEmphasisStageParameters(1, gain, anchorFreq / filterStageRatio);
setEmphasisStageParameters(2, gain, anchorFreq / (filterStageRatio * filterStageRatio));
setEmphasisStageParameters(3, gain, anchorFreq / (filterStageRatio * filterStageRatio * filterStageRatio));
}
void DynamicsCompressor::process(const AudioBus* sourceBus, AudioBus* destinationBus, unsigned framesToProcess)
{
const float* sourceL = sourceBus->channel(0)->data();
const float* sourceR;
if (sourceBus->numberOfChannels() > 1)
sourceR = sourceBus->channel(1)->data();
else
sourceR = sourceL;
ASSERT(destinationBus->numberOfChannels() == 2);
float* destinationL = destinationBus->channel(0)->mutableData();
float* destinationR = destinationBus->channel(1)->mutableData();
float filterStageGain = parameterValue(ParamFilterStageGain);
float filterStageRatio = parameterValue(ParamFilterStageRatio);
float anchor = parameterValue(ParamFilterAnchor);
if (filterStageGain != m_lastFilterStageGain || filterStageRatio != m_lastFilterStageRatio || anchor != m_lastAnchor) {
m_lastFilterStageGain = filterStageGain;
m_lastFilterStageRatio = filterStageRatio;
m_lastAnchor = anchor;
setEmphasisParameters(filterStageGain, anchor, filterStageRatio);
}
// Apply pre-emphasis filter.
// Note that the final three stages are computed in-place in the destination buffer.
m_preFilter[0].process(sourceL, destinationL, framesToProcess);
m_preFilter[1].process(destinationL, destinationL, framesToProcess);
m_preFilter[2].process(destinationL, destinationL, framesToProcess);
m_preFilter[3].process(destinationL, destinationL, framesToProcess);
if (isStereo()) {
m_preFilterR[0].process(sourceR, destinationR, framesToProcess);
m_preFilterR[1].process(destinationR, destinationR, framesToProcess);
m_preFilterR[2].process(destinationR, destinationR, framesToProcess);
m_preFilterR[3].process(destinationR, destinationR, framesToProcess);
}
float dbThreshold = parameterValue(ParamThreshold);
float dbHeadroom = parameterValue(ParamHeadroom);
float attackTime = parameterValue(ParamAttack);
float releaseTime = parameterValue(ParamRelease);
float preDelayTime = parameterValue(ParamPreDelay);
// This is effectively a master volume on the compressed signal (pre-blending).
float dbPostGain = parameterValue(ParamPostGain);
// Linear blending value from dry to completely processed (0 -> 1)
// 0 means the signal is completely unprocessed.
// 1 mixes in only the compressed signal.
float effectBlend = parameterValue(ParamEffectBlend);
float releaseZone1 = parameterValue(ParamReleaseZone1);
float releaseZone2 = parameterValue(ParamReleaseZone2);
float releaseZone3 = parameterValue(ParamReleaseZone3);
float releaseZone4 = parameterValue(ParamReleaseZone4);
// Apply compression to the pre-filtered signal.
// The processing is performed in place.
m_compressor.process(destinationL,
destinationL,
destinationR,
destinationR,
framesToProcess,
dbThreshold,
dbHeadroom,
attackTime,
releaseTime,
preDelayTime,
dbPostGain,
effectBlend,
releaseZone1,
releaseZone2,
releaseZone3,
releaseZone4
);
// Apply de-emphasis filter.
m_postFilter[0].process(destinationL, destinationL, framesToProcess);
m_postFilter[1].process(destinationL, destinationL, framesToProcess);
m_postFilter[2].process(destinationL, destinationL, framesToProcess);
m_postFilter[3].process(destinationL, destinationL, framesToProcess);
if (isStereo()) {
m_postFilterR[0].process(destinationR, destinationR, framesToProcess);
m_postFilterR[1].process(destinationR, destinationR, framesToProcess);
m_postFilterR[2].process(destinationR, destinationR, framesToProcess);
m_postFilterR[3].process(destinationR, destinationR, framesToProcess);
}
}
void DynamicsCompressor::reset()
{
m_lastFilterStageRatio = -1; // for recalc
m_lastAnchor = -1;
m_lastFilterStageGain = -1;
for (unsigned i = 0; i < 4; ++i) {
m_preFilter[i].reset();
m_preFilterR[i].reset();
m_postFilter[i].reset();
m_postFilterR[i].reset();
}
m_compressor.reset();
}
} // namespace WebCore
#endif // ENABLE(WEB_AUDIO)
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