residual_echo_detector.h

/*

 *  Copyright (c) 2016 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_RESIDUAL_ECHO_DETECTOR_H_

#define MODULES_AUDIO_PROCESSING_RESIDUAL_ECHO_DETECTOR_H_

#include <atomic>

#include <vector>

#include "api/array_view.h"

#include "api/audio/audio_processing.h"

#include "modules/audio_processing/echo_detector/circular_buffer.h"

#include "modules/audio_processing/echo_detector/mean_variance_estimator.h"

#include "modules/audio_processing/echo_detector/moving_max.h"

#include "modules/audio_processing/echo_detector/normalized_covariance_estimator.h"

namespace webrtc {

class ApmDataDumper;

class AudioBuffer;

class ResidualEchoDetector : public EchoDetector {

 public:

  ResidualEchoDetector();

  ~ResidualEchoDetector() override;

  // This function should be called while holding the render lock.

  void AnalyzeRenderAudio(rtc::ArrayView<const float> render_audio) override;

  // This function should be called while holding the capture lock.

  void AnalyzeCaptureAudio(rtc::ArrayView<const float> capture_audio) override;

  // This function should be called while holding the capture lock.

  void Initialize(int capture_sample_rate_hz,

                  int num_capture_channels,

                  int render_sample_rate_hz,

                  int num_render_channels) override;

  // This function is for testing purposes only.

  void SetReliabilityForTest(float value) { reliability_ = value; }

  // This function should be called while holding the capture lock.

  EchoDetector::Metrics GetMetrics() const override;

 private:

  static std::atomic<int> instance_count_;

  std::unique_ptr<ApmDataDumper> data_dumper_;

  // Keep track if the `Process` function has been previously called.

  bool first_process_call_ = true;

  // Buffer for storing the power of incoming farend buffers. This is needed for

  // cases where calls to BufferFarend and Process are jittery.

  CircularBuffer render_buffer_;

  // Count how long ago it was that the size of `render_buffer_` was zero. This

  // value is also reset to zero when clock drift is detected and a value from

  // the renderbuffer is discarded, even though the buffer is not actually zero

  // at that point. This is done to avoid repeatedly removing elements in this

  // situation.

  size_t frames_since_zero_buffer_size_ = 0;

  // Circular buffers containing delayed versions of the power, mean and

  // standard deviation, for calculating the delayed covariance values.

  std::vector<float> render_power_;

  std::vector<float> render_power_mean_;

  std::vector<float> render_power_std_dev_;

  // Covariance estimates for different delay values.

  std::vector<NormalizedCovarianceEstimator> covariances_;

  // Index where next element should be inserted in all of the above circular

  // buffers.

  size_t next_insertion_index_ = 0;

  MeanVarianceEstimator render_statistics_;

  MeanVarianceEstimator capture_statistics_;

  // Current echo likelihood.

  float echo_likelihood_ = 0.f;

  // Reliability of the current likelihood.

  float reliability_ = 0.f;

  MovingMax recent_likelihood_max_;

  int log_counter_ = 0;

};

}  // namespace webrtc

#endif  // MODULES_AUDIO_PROCESSING_RESIDUAL_ECHO_DETECTOR_H_