vad_audio_proc.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_PROCESSING_VAD_VAD_AUDIO_PROC_H_

#define MODULES_AUDIO_PROCESSING_VAD_VAD_AUDIO_PROC_H_

#include <stddef.h>

#include <stdint.h>

#include <memory>

#include "modules/audio_processing/vad/common.h"  // AudioFeatures, kSampleR...

namespace webrtc {

class PoleZeroFilter;

class VadAudioProc {

 public:

  // Forward declare iSAC structs.

  struct PitchAnalysisStruct;

  struct PreFiltBankstr;

  VadAudioProc();

  ~VadAudioProc();

  int ExtractFeatures(const int16_t* audio_frame,

                      size_t length,

                      AudioFeatures* audio_features);

  static constexpr size_t kDftSize = 512;

 private:

  void PitchAnalysis(double* pitch_gains, double* pitch_lags_hz, size_t length);

  void SubframeCorrelation(double* corr,

                           size_t length_corr,

                           size_t subframe_index);

  void GetLpcPolynomials(double* lpc, size_t length_lpc);

  void FindFirstSpectralPeaks(double* f_peak, size_t length_f_peak);

  void Rms(double* rms, size_t length_rms);

  void ResetBuffer();

  // To compute spectral peak we perform LPC analysis to get spectral envelope.

  // For every 30 ms we compute 3 spectral peak there for 3 LPC analysis.

  // LPC is computed over 15 ms of windowed audio. For every 10 ms sub-frame

  // we need 5 ms of past signal to create the input of LPC analysis.

  static constexpr size_t kNumPastSignalSamples = size_t{kSampleRateHz / 200};

  // TODO(turajs): maybe defining this at a higher level (maybe enum) so that

  // all the code recognize it as "no-error."

  static constexpr int kNoError = 0;

  static constexpr size_t kNum10msSubframes = 3;

  static constexpr size_t kNumSubframeSamples = size_t{kSampleRateHz / 100};

  // Samples in 30 ms @ given sampling rate.

  static constexpr size_t kNumSamplesToProcess =

      kNum10msSubframes * kNumSubframeSamples;

  static constexpr size_t kBufferLength =

      kNumPastSignalSamples + kNumSamplesToProcess;

  static constexpr size_t kIpLength = kDftSize >> 1;

  static constexpr size_t kWLength = kDftSize >> 1;

  static constexpr size_t kLpcOrder = 16;

  size_t ip_[kIpLength];

  float w_fft_[kWLength];

  // A buffer of 5 ms (past audio) + 30 ms (one iSAC frame ).

  float audio_buffer_[kBufferLength];

  size_t num_buffer_samples_;

  double log_old_gain_;

  double old_lag_;

  std::unique_ptr<PitchAnalysisStruct> pitch_analysis_handle_;

  std::unique_ptr<PreFiltBankstr> pre_filter_handle_;

  std::unique_ptr<PoleZeroFilter> high_pass_filter_;

};

}  // namespace webrtc

#endif  // MODULES_AUDIO_PROCESSING_VAD_VAD_AUDIO_PROC_H_