vad_wrapper.h - mozsearch

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/*

 *  Copyright (c) 2018 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_AGC2_VAD_WRAPPER_H_

#define MODULES_AUDIO_PROCESSING_AGC2_VAD_WRAPPER_H_

#include <memory>

#include <vector>

#include "api/audio/audio_view.h"

#include "common_audio/resampler/include/push_resampler.h"

#include "modules/audio_processing/agc2/cpu_features.h"

namespace webrtc {

// Wraps a single-channel Voice Activity Detector (VAD) which is used to analyze

// the first channel of the input audio frames. Takes care of resampling the

// input frames to match the sample rate of the wrapped VAD and periodically

// resets the VAD.

class VoiceActivityDetectorWrapper {

 public:

  // Single channel VAD interface.

  class MonoVad {

   public:

    virtual ~MonoVad() = default;

    // Returns the sample rate (Hz) required for the input frames analyzed by

    // `ComputeProbability`.

    virtual int SampleRateHz() const = 0;

    // Resets the internal state.

    virtual void Reset() = 0;

    // Analyzes an audio frame and returns the speech probability.

    virtual float Analyze(MonoView<const float> frame) = 0;

};

  // Ctor. Uses `cpu_features` to instantiate the default VAD.

  VoiceActivityDetectorWrapper(const AvailableCpuFeatures& cpu_features,

                               int sample_rate_hz);

  // Ctor. `vad_reset_period_ms` indicates the period in milliseconds to call

  // `MonoVad::Reset()`; it must be equal to or greater than the duration of two

  // frames. Uses `cpu_features` to instantiate the default VAD.

  VoiceActivityDetectorWrapper(int vad_reset_period_ms,

                               const AvailableCpuFeatures& cpu_features,

                               int sample_rate_hz);

  // Ctor. Uses a custom `vad`.

  VoiceActivityDetectorWrapper(int vad_reset_period_ms,

                               std::unique_ptr<MonoVad> vad,

                               int sample_rate_hz);

  VoiceActivityDetectorWrapper(const VoiceActivityDetectorWrapper&) = delete;

  VoiceActivityDetectorWrapper& operator=(const VoiceActivityDetectorWrapper&) =

      delete;

  ~VoiceActivityDetectorWrapper();

  // Analyzes the first channel of `frame` and returns the speech probability.

  // `frame` must be a 10 ms frame with the sample rate specified in the last

  // `Initialize()` call.

  float Analyze(DeinterleavedView<const float> frame);

 private:

  const int vad_reset_period_frames_;

  const int frame_size_;

  int time_to_vad_reset_;

  std::unique_ptr<MonoVad> vad_;

  std::vector<float> resampled_buffer_;

  PushResampler<float> resampler_;

};

}  // namespace webrtc

#endif  // MODULES_AUDIO_PROCESSING_AGC2_VAD_WRAPPER_H_