modules/audio_processing/aec3/echo_audibility.h

/*
 *  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_AEC3_ECHO_AUDIBILITY_H_
#define MODULES_AUDIO_PROCESSING_AEC3_ECHO_AUDIBILITY_H_

#include <stddef.h>

#include "absl/types/optional.h"
#include "api/array_view.h"
#include "modules/audio_processing/aec3/block_buffer.h"
#include "modules/audio_processing/aec3/render_buffer.h"
#include "modules/audio_processing/aec3/spectrum_buffer.h"
#include "modules/audio_processing/aec3/stationarity_estimator.h"

namespace webrtc {

class EchoAudibility {
 public:
  explicit EchoAudibility(bool use_render_stationarity_at_init);
  ~EchoAudibility();

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

  // Feed new render data to the echo audibility estimator.
  void Update(const RenderBuffer& render_buffer,
              rtc::ArrayView<const float> average_reverb,
              int min_channel_delay_blocks,
              bool external_delay_seen);
  // Get the residual echo scaling.
  void GetResidualEchoScaling(bool filter_has_had_time_to_converge,
                              rtc::ArrayView<float> residual_scaling) const {
    for (size_t band = 0; band < residual_scaling.size(); ++band) {
      if (render_stationarity_.IsBandStationary(band) &&
          (filter_has_had_time_to_converge ||
           use_render_stationarity_at_init_)) {
        residual_scaling[band] = 0.f;
      } else {
        residual_scaling[band] = 1.0f;
      }
    }
  }

  // Returns true if the current render block is estimated as stationary.
  bool IsBlockStationary() const {
    return render_stationarity_.IsBlockStationary();
  }

 private:
  // Reset the EchoAudibility class.
  void Reset();

  // Updates the render stationarity flags for the current frame.
  void UpdateRenderStationarityFlags(const RenderBuffer& render_buffer,
                                     rtc::ArrayView<const float> average_reverb,
                                     int delay_blocks);

  // Updates the noise estimator with the new render data since the previous
  // call to this method.
  void UpdateRenderNoiseEstimator(const SpectrumBuffer& spectrum_buffer,
                                  const BlockBuffer& block_buffer,
                                  bool external_delay_seen);

  // Returns a bool being true if the render signal contains just close to zero
  // values.
  bool IsRenderTooLow(const BlockBuffer& block_buffer);

  absl::optional<int> render_spectrum_write_prev_;
  int render_block_write_prev_;
  bool non_zero_render_seen_;
  const bool use_render_stationarity_at_init_;
  StationarityEstimator render_stationarity_;
};

}  // namespace webrtc

#endif  // MODULES_AUDIO_PROCESSING_AEC3_ECHO_AUDIBILITY_H_