/* * 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 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 "AudioArray.h" #include <memory> #include <wtf/Vector.h> namespace WebCore { class DynamicsCompressorKernel final { WTF_MAKE_FAST_ALLOCATED; public: explicit DynamicsCompressorKernel(float sampleRate, unsigned numberOfChannels); void setNumberOfChannels(unsigned); // Performs stereo-linked compression. void process(const 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; } double tailTime() const; protected: static constexpr float uninitializedValue = -1; 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 { DefaultPreDelayFrames }; void setPreDelayTime(float); Vector<std::unique_ptr<AudioFloatArray>> m_preDelayBuffers; int m_preDelayReadIndex { 0 }; int m_preDelayWriteIndex { DefaultPreDelayFrames }; 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 { uninitializedValue }; float m_slope { uninitializedValue }; // Inverse ratio. // The input to output change below the threshold is linear 1:1. float m_linearThreshold { uninitializedValue }; float m_dbThreshold { uninitializedValue }; // 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 { uninitializedValue }; float m_kneeThreshold { uninitializedValue }; float m_kneeThresholdDb { uninitializedValue }; float m_ykneeThresholdDb { uninitializedValue }; // Internal parameter for the knee portion of the curve. float m_K { uninitializedValue }; }; } // namespace WebCore #endif // DynamicsCompressorKernel_h