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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.
*/
#ifndef DynamicsCompressorKernel_h
#define DynamicsCompressorKernel_h
#include "nsTArray.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/UniquePtr.h"
namespace WebCore {
class DynamicsCompressorKernel {
public:
DynamicsCompressorKernel(float sampleRate, unsigned numberOfChannels);
void setNumberOfChannels(unsigned);
// Performs stereo-linked compression.
void process(float* sourceChannels[],
float* destinationChannels[],
unsigned numberOfChannels,
unsigned framesToProcess,
float dbThreshold,
float dbKnee,
float ratio,
float attackTime,
float releaseTime,
float preDelayTime,
float dbPostGain,
float effectBlend,
float releaseZone1,
float releaseZone2,
float releaseZone3,
float releaseZone4
);
void reset();
unsigned latencyFrames() const { return m_lastPreDelayFrames; }
float sampleRate() const { return m_sampleRate; }
float meteringGain() const { return m_meteringGain; }
size_t sizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
protected:
float m_sampleRate;
float m_detectorAverage;
float m_compressorGain;
// Metering
float m_meteringReleaseK;
float m_meteringGain;
// Lookahead section.
enum { MaxPreDelayFrames = 1024 };
enum { MaxPreDelayFramesMask = MaxPreDelayFrames - 1 };
enum { DefaultPreDelayFrames = 256 }; // setPreDelayTime() will override this initial value
unsigned m_lastPreDelayFrames;
void setPreDelayTime(float);
nsTArray<mozilla::UniquePtr<float[]>> m_preDelayBuffers;
int m_preDelayReadIndex;
int m_preDelayWriteIndex;
float m_maxAttackCompressionDiffDb;
// Static compression curve.
float kneeCurve(float x, float k);
float saturate(float x, float k);
float slopeAt(float x, float k);
float kAtSlope(float desiredSlope);
float updateStaticCurveParameters(float dbThreshold, float dbKnee, float ratio);
// Amount of input change in dB required for 1 dB of output change.
// This applies to the portion of the curve above m_kneeThresholdDb (see below).
float m_ratio;
float m_slope; // Inverse ratio.
// The input to output change below the threshold is linear 1:1.
float m_linearThreshold;
float m_dbThreshold;
// m_dbKnee is the number of dB above the threshold before we enter the "ratio" portion of the curve.
// m_kneeThresholdDb = m_dbThreshold + m_dbKnee
// The portion between m_dbThreshold and m_kneeThresholdDb is the "soft knee" portion of the curve
// which transitions smoothly from the linear portion to the ratio portion.
float m_dbKnee;
float m_kneeThreshold;
float m_kneeThresholdDb;
float m_ykneeThresholdDb;
// Internal parameter for the knee portion of the curve.
float m_K;
};
} // namespace WebCore
#endif // DynamicsCompressorKernel_h
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