vad_circular_buffer.h

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/*

 *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.

 *  Use of this source code is governed by a BSD-style license

 *  that can be found in the LICENSE file in the root of the source

 *  tree. An additional intellectual property rights grant can be found

 *  in the file PATENTS.  All contributing project authors may

 *  be found in the AUTHORS file in the root of the source tree.

*/

#ifndef MODULES_AUDIO_PROCESSING_VAD_VAD_CIRCULAR_BUFFER_H_

#define MODULES_AUDIO_PROCESSING_VAD_VAD_CIRCULAR_BUFFER_H_

#include <memory>

namespace webrtc {

// A circular buffer tailored to the need of this project. It stores last

// K samples of the input, and keeps track of the mean of the last samples.

//

// It is used in class "PitchBasedActivity" to keep track of posterior

// probabilities in the past few seconds. The posterior probabilities are used

// to recursively update prior probabilities.

class VadCircularBuffer {

 public:

  static VadCircularBuffer* Create(int buffer_size);

  ~VadCircularBuffer();

  // If buffer is wrapped around.

  bool is_full() const { return is_full_; }

  // Get the oldest entry in the buffer.

  double Oldest() const;

  // Insert new value into the buffer.

  void Insert(double value);

  // Reset buffer, forget the past, start fresh.

  void Reset();

  // The mean value of the elements in the buffer. The return value is zero if

  // buffer is empty, i.e. no value is inserted.

  double Mean();

  // Remove transients. If the values exceed `val_threshold` for a period

  // shorter then or equal to `width_threshold`, then that period is considered

  // transient and set to zero.

  int RemoveTransient(int width_threshold, double val_threshold);

 private:

  explicit VadCircularBuffer(int buffer_size);

  // Get previous values. |index = 0| corresponds to the most recent

  // insertion. |index = 1| is the one before the most recent insertion, and

  // so on.

  int Get(int index, double* value) const;

  // Set a given position to `value`. `index` is interpreted as above.

  int Set(int index, double value);

  // Return the number of valid elements in the buffer.

  int BufferLevel();

  // Convert an index with the interpretation as get() method to the

  // corresponding linear index.

  int ConvertToLinearIndex(int* index) const;

  std::unique_ptr<double[]> buffer_;

  bool is_full_;

  int index_;

  int buffer_size_;

  double sum_;

};

}  // namespace webrtc

#endif  // MODULES_AUDIO_PROCESSING_VAD_VAD_CIRCULAR_BUFFER_H_