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128 lines
4.4 KiB
C++
128 lines
4.4 KiB
C++
/*
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* Copyright (C) 2011 Google Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
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* its contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef DynamicsCompressorKernel_h
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#define DynamicsCompressorKernel_h
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#include "nsTArray.h"
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#include "nsAutoPtr.h"
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namespace WebCore {
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class DynamicsCompressorKernel {
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public:
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DynamicsCompressorKernel(float sampleRate, unsigned numberOfChannels);
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void setNumberOfChannels(unsigned);
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// Performs stereo-linked compression.
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void process(float* sourceChannels[],
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float* destinationChannels[],
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unsigned numberOfChannels,
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unsigned framesToProcess,
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float dbThreshold,
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float dbKnee,
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float ratio,
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float attackTime,
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float releaseTime,
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float preDelayTime,
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float dbPostGain,
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float effectBlend,
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float releaseZone1,
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float releaseZone2,
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float releaseZone3,
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float releaseZone4
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);
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void reset();
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unsigned latencyFrames() const { return m_lastPreDelayFrames; }
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float sampleRate() const { return m_sampleRate; }
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float meteringGain() const { return m_meteringGain; }
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protected:
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float m_sampleRate;
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float m_detectorAverage;
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float m_compressorGain;
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// Metering
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float m_meteringReleaseK;
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float m_meteringGain;
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// Lookahead section.
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enum { MaxPreDelayFrames = 1024 };
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enum { MaxPreDelayFramesMask = MaxPreDelayFrames - 1 };
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enum { DefaultPreDelayFrames = 256 }; // setPreDelayTime() will override this initial value
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unsigned m_lastPreDelayFrames;
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void setPreDelayTime(float);
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nsTArray<nsAutoArrayPtr<float> > m_preDelayBuffers;
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int m_preDelayReadIndex;
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int m_preDelayWriteIndex;
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float m_maxAttackCompressionDiffDb;
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// Static compression curve.
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float kneeCurve(float x, float k);
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float saturate(float x, float k);
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float slopeAt(float x, float k);
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float kAtSlope(float desiredSlope);
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float updateStaticCurveParameters(float dbThreshold, float dbKnee, float ratio);
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// Amount of input change in dB required for 1 dB of output change.
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// This applies to the portion of the curve above m_kneeThresholdDb (see below).
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float m_ratio;
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float m_slope; // Inverse ratio.
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// The input to output change below the threshold is linear 1:1.
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float m_linearThreshold;
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float m_dbThreshold;
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// m_dbKnee is the number of dB above the threshold before we enter the "ratio" portion of the curve.
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// m_kneeThresholdDb = m_dbThreshold + m_dbKnee
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// The portion between m_dbThreshold and m_kneeThresholdDb is the "soft knee" portion of the curve
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// which transitions smoothly from the linear portion to the ratio portion.
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float m_dbKnee;
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float m_kneeThreshold;
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float m_kneeThresholdDb;
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float m_ykneeThresholdDb;
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// Internal parameter for the knee portion of the curve.
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float m_K;
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};
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} // namespace WebCore
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#endif // DynamicsCompressorKernel_h
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