accelerate.h - mozsearch

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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_CODING_NETEQ_ACCELERATE_H_

#define MODULES_AUDIO_CODING_NETEQ_ACCELERATE_H_

#include <stddef.h>

#include <stdint.h>

#include "modules/audio_coding/neteq/time_stretch.h"

namespace webrtc {

class AudioMultiVector;

class BackgroundNoise;

// This class implements the Accelerate operation. Most of the work is done

// in the base class TimeStretch, which is shared with the PreemptiveExpand

// operation. In the Accelerate class, the operations that are specific to

// Accelerate are implemented.

class Accelerate : public TimeStretch {

 public:

  Accelerate(int sample_rate_hz,

             size_t num_channels,

             const BackgroundNoise& background_noise)

      : TimeStretch(sample_rate_hz, num_channels, background_noise) {}

  Accelerate(const Accelerate&) = delete;

  Accelerate& operator=(const Accelerate&) = delete;

  // This method performs the actual Accelerate operation. The samples are

  // read from `input`, of length `input_length` elements, and are written to

  // `output`. The number of samples removed through time-stretching is

  // is provided in the output `length_change_samples`. The method returns

  // the outcome of the operation as an enumerator value. If `fast_accelerate`

  // is true, the algorithm will relax the requirements on finding strong

  // correlations, and may remove multiple pitch periods if possible.

  ReturnCodes Process(const int16_t* input,

                      size_t input_length,

                      bool fast_accelerate,

                      AudioMultiVector* output,

                      size_t* length_change_samples);

 protected:

  // Sets the parameters `best_correlation` and `peak_index` to suitable

  // values when the signal contains no active speech.

  void SetParametersForPassiveSpeech(size_t len,

                                     int16_t* best_correlation,

                                     size_t* peak_index) const override;

  // Checks the criteria for performing the time-stretching operation and,

  // if possible, performs the time-stretching.

  ReturnCodes CheckCriteriaAndStretch(const int16_t* input,

                                      size_t input_length,

                                      size_t peak_index,

                                      int16_t best_correlation,

                                      bool active_speech,

                                      bool fast_mode,

                                      AudioMultiVector* output) const override;

};

struct AccelerateFactory {

  AccelerateFactory() {}

  virtual ~AccelerateFactory() {}

  virtual Accelerate* Create(int sample_rate_hz,

                             size_t num_channels,

                             const BackgroundNoise& background_noise) const;

};

}  // namespace webrtc

#endif  // MODULES_AUDIO_CODING_NETEQ_ACCELERATE_H_