DynamicsCompressor.h

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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

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 * 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

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*/

#ifndef DynamicsCompressor_h

#define DynamicsCompressor_h

#include "DynamicsCompressorKernel.h"

#include "ZeroPole.h"

#include "nsTArray.h"

#include "mozilla/MemoryReporting.h"

#include "mozilla/UniquePtr.h"

namespace mozilla {

class AudioBlock;

}  // namespace mozilla

namespace WebCore {

using mozilla::AudioBlock;

using mozilla::UniquePtr;

// DynamicsCompressor implements a flexible audio dynamics compression effect

// such as is commonly used in musical production and game audio. It lowers the

// volume of the loudest parts of the signal and raises the volume of the

// softest parts, making the sound richer, fuller, and more controlled.

class DynamicsCompressor {

 public:

  enum {

    ParamThreshold,

    ParamKnee,

    ParamRatio,

    ParamAttack,

    ParamRelease,

    ParamPreDelay,

    ParamReleaseZone1,

    ParamReleaseZone2,

    ParamReleaseZone3,

    ParamReleaseZone4,

    ParamPostGain,

    ParamFilterStageGain,

    ParamFilterStageRatio,

    ParamFilterAnchor,

    ParamEffectBlend,

    ParamReduction,

    ParamLast

};

  DynamicsCompressor(float sampleRate, unsigned numberOfChannels);

  void process(const AudioBlock* sourceChunk, AudioBlock* destinationChunk,

               unsigned framesToProcess);

  void reset();

  void setNumberOfChannels(unsigned);

  unsigned numberOfChannels() const { return m_numberOfChannels; }

  void setParameterValue(unsigned parameterID, float value);

  float parameterValue(unsigned parameterID);

  float sampleRate() const { return m_sampleRate; }

  float nyquist() const { return m_sampleRate / 2; }

  double tailTime() const { return 0; }

  double latencyTime() const {

    return m_compressor.latencyFrames() / static_cast<double>(sampleRate());

  size_t sizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;

 protected:

  unsigned m_numberOfChannels;

  // m_parameters holds the tweakable compressor parameters.

  float m_parameters[ParamLast];

  void initializeParameters();

  float m_sampleRate;

  // Emphasis filter controls.

  float m_lastFilterStageRatio;

  float m_lastAnchor;

  float m_lastFilterStageGain;

  struct ZeroPoleFilterPack4 {

    ZeroPole filters[4];

    size_t sizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {

      return aMallocSizeOf(this);

};

  // Per-channel emphasis filters.

  nsTArray<UniquePtr<ZeroPoleFilterPack4> > m_preFilterPacks;

  nsTArray<UniquePtr<ZeroPoleFilterPack4> > m_postFilterPacks;

  mozilla::UniquePtr<const float*[]> m_sourceChannels;

  mozilla::UniquePtr<float*[]> m_destinationChannels;

  void setEmphasisStageParameters(unsigned stageIndex, float gain,

                                  float normalizedFrequency /* 0 -> 1 */);

  void setEmphasisParameters(float gain, float anchorFreq,

                             float filterStageRatio);

  // The core compressor.

  DynamicsCompressorKernel m_compressor;

};

}  // namespace WebCore

#endif  // DynamicsCompressor_h