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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 "platform/audio/AudioBus.h"
#include "platform/audio/AudioUtilities.h"
#include "platform/audio/DynamicsCompressor.h"
#include "wtf/MathExtras.h"
#include "wtf/PtrUtil.h"
namespace blink {
using namespace AudioUtilities;
DynamicsCompressor::DynamicsCompressor(float sampleRate,
unsigned numberOfChannels)
: m_numberOfChannels(numberOfChannels),
m_sampleRate(sampleRate),
m_compressor(sampleRate, numberOfChannels) {
// Uninitialized state - for parameter recalculation.
m_lastFilterStageRatio = -1;
m_lastAnchor = -1;
m_lastFilterStageGain = -1;
setNumberOfChannels(numberOfChannels);
initializeParameters();
}
void DynamicsCompressor::setParameterValue(unsigned parameterID, float value) {
ASSERT(parameterID < ParamLast);
if (parameterID < ParamLast)
m_parameters[parameterID] = value;
}
void DynamicsCompressor::initializeParameters() {
// Initializes compressor to default values.
m_parameters[ParamThreshold] = -24; // dB
m_parameters[ParamKnee] = 30; // dB
m_parameters[ParamRatio] = 12; // unit-less
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
m_parameters[ParamReduction] = 0; // dB
// Linear crossfade (0 -> 1).
m_parameters[ParamEffectBlend] = 1;
}
float DynamicsCompressor::parameterValue(unsigned parameterID) {
ASSERT(parameterID < ParamLast);
return m_parameters[parameterID];
}
void DynamicsCompressor::process(const AudioBus* sourceBus,
AudioBus* destinationBus,
unsigned framesToProcess) {
// Though numberOfChannels is retrived from destinationBus, we still name it
// numberOfChannels instead of numberOfDestinationChannels. It's because we
// internally match sourceChannels's size to destinationBus by channel
// up/down mix. Thus we need numberOfChannels
// to do the loop work for both m_sourceChannels and m_destinationChannels.
unsigned numberOfChannels = destinationBus->numberOfChannels();
unsigned numberOfSourceChannels = sourceBus->numberOfChannels();
ASSERT(numberOfChannels == m_numberOfChannels && numberOfSourceChannels);
if (numberOfChannels != m_numberOfChannels || !numberOfSourceChannels) {
destinationBus->zero();
return;
}
switch (numberOfChannels) {
case 2: // stereo
m_sourceChannels[0] = sourceBus->channel(0)->data();
if (numberOfSourceChannels > 1)
m_sourceChannels[1] = sourceBus->channel(1)->data();
else
// Simply duplicate mono channel input data to right channel for stereo
// processing.
m_sourceChannels[1] = m_sourceChannels[0];
break;
default:
// FIXME : support other number of channels.
NOTREACHED();
destinationBus->zero();
return;
}
for (unsigned i = 0; i < numberOfChannels; ++i)
m_destinationChannels[i] = destinationBus->channel(i)->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;
}
float dbThreshold = parameterValue(ParamThreshold);
float dbKnee = parameterValue(ParamKnee);
float ratio = parameterValue(ParamRatio);
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 source signal.
m_compressor.process(m_sourceChannels.get(), m_destinationChannels.get(),
numberOfChannels, framesToProcess,
dbThreshold, dbKnee, ratio, attackTime, releaseTime,
preDelayTime, dbPostGain, effectBlend,
releaseZone1, releaseZone2, releaseZone3, releaseZone4);
// Update the compression amount.
setParameterValue(ParamReduction, m_compressor.meteringGain());
}
void DynamicsCompressor::reset() {
m_lastFilterStageRatio = -1; // for recalc
m_lastAnchor = -1;
m_lastFilterStageGain = -1;
m_compressor.reset();
}
void DynamicsCompressor::setNumberOfChannels(unsigned numberOfChannels) {
m_sourceChannels = wrapArrayUnique(new const float*[numberOfChannels]);
m_destinationChannels = wrapArrayUnique(new float*[numberOfChannels]);
m_compressor.setNumberOfChannels(numberOfChannels);
m_numberOfChannels = numberOfChannels;
}
} // namespace blink
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