third_party/WebKit/Source/modules/webaudio/RealtimeAnalyser.h

/*
 * Copyright (C) 2010, 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.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. 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 INC. 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 RealtimeAnalyser_h
#define RealtimeAnalyser_h

#include "core/dom/DOMTypedArray.h"
#include "platform/audio/AudioArray.h"
#include "platform/audio/FFTFrame.h"
#include "wtf/Noncopyable.h"
#include <memory>

namespace blink {

class AudioBus;

class RealtimeAnalyser final {
  WTF_MAKE_NONCOPYABLE(RealtimeAnalyser);
  DISALLOW_NEW();

 public:
  RealtimeAnalyser();

  size_t fftSize() const { return m_fftSize; }
  bool setFftSize(size_t);

  unsigned frequencyBinCount() const { return m_fftSize / 2; }

  void setMinDecibels(double k) { m_minDecibels = k; }
  double minDecibels() const { return m_minDecibels; }

  void setMaxDecibels(double k) { m_maxDecibels = k; }
  double maxDecibels() const { return m_maxDecibels; }

  void setSmoothingTimeConstant(double k) { m_smoothingTimeConstant = k; }
  double smoothingTimeConstant() const { return m_smoothingTimeConstant; }

  void getFloatFrequencyData(DOMFloat32Array*, double);
  void getByteFrequencyData(DOMUint8Array*, double);
  void getFloatTimeDomainData(DOMFloat32Array*);
  void getByteTimeDomainData(DOMUint8Array*);

  // The audio thread writes input data here.
  void writeInput(AudioBus*, size_t framesToProcess);

  static const double DefaultSmoothingTimeConstant;
  static const double DefaultMinDecibels;
  static const double DefaultMaxDecibels;

  static const unsigned DefaultFFTSize;
  static const unsigned MinFFTSize;
  static const unsigned MaxFFTSize;
  static const unsigned InputBufferSize;

 private:
  // The audio thread writes the input audio here.
  AudioFloatArray m_inputBuffer;
  unsigned m_writeIndex;

  // Input audio is downmixed to this bus before copying to m_inputBuffer.
  RefPtr<AudioBus> m_downMixBus;

  size_t m_fftSize;
  std::unique_ptr<FFTFrame> m_analysisFrame;
  void doFFTAnalysis();

  // Convert the contents of magnitudeBuffer to byte values, saving the result
  // in |destination|.
  void convertToByteData(DOMUint8Array* destination);

  // Convert magnidue buffer to dB, saving the result in |destination|
  void convertFloatToDb(DOMFloat32Array* destination);

  // doFFTAnalysis() stores the floating-point magnitude analysis data here.
  AudioFloatArray m_magnitudeBuffer;
  AudioFloatArray& magnitudeBuffer() { return m_magnitudeBuffer; }

  // A value between 0 and 1 which averages the previous version of
  // m_magnitudeBuffer with the current analysis magnitude data.
  double m_smoothingTimeConstant;

  // The range used when converting when using getByteFrequencyData().
  double m_minDecibels;
  double m_maxDecibels;

  // Time at which the FFT was last computed.
  double m_lastAnalysisTime;
};

}  // namespace blink

#endif  // RealtimeAnalyser_h