subtractor.h - mozsearch

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/*

 *  Copyright (c) 2017 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_SUBTRACTOR_H_

#define MODULES_AUDIO_PROCESSING_AEC3_SUBTRACTOR_H_

#include <math.h>

#include <stddef.h>

#include <array>

#include <vector>

#include "api/array_view.h"

#include "api/audio/echo_canceller3_config.h"

#include "modules/audio_processing/aec3/adaptive_fir_filter.h"

#include "modules/audio_processing/aec3/aec3_common.h"

#include "modules/audio_processing/aec3/aec3_fft.h"

#include "modules/audio_processing/aec3/aec_state.h"

#include "modules/audio_processing/aec3/block.h"

#include "modules/audio_processing/aec3/coarse_filter_update_gain.h"

#include "modules/audio_processing/aec3/echo_path_variability.h"

#include "modules/audio_processing/aec3/refined_filter_update_gain.h"

#include "modules/audio_processing/aec3/render_buffer.h"

#include "modules/audio_processing/aec3/render_signal_analyzer.h"

#include "modules/audio_processing/aec3/subtractor_output.h"

#include "modules/audio_processing/logging/apm_data_dumper.h"

#include "rtc_base/checks.h"

namespace webrtc {

// Proves linear echo cancellation functionality

class Subtractor {

 public:

  Subtractor(const EchoCanceller3Config& config,

             size_t num_render_channels,

             size_t num_capture_channels,

             ApmDataDumper* data_dumper,

             Aec3Optimization optimization);

  ~Subtractor();

  Subtractor(const Subtractor&) = delete;

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

  // Performs the echo subtraction.

  void Process(const RenderBuffer& render_buffer,

               const Block& capture,

               const RenderSignalAnalyzer& render_signal_analyzer,

               const AecState& aec_state,

               rtc::ArrayView<SubtractorOutput> outputs);

  void HandleEchoPathChange(const EchoPathVariability& echo_path_variability);

  // Exits the initial state.

  void ExitInitialState();

  // Returns the block-wise frequency responses for the refined adaptive

  // filters.

  const std::vector<std::vector<std::array<float, kFftLengthBy2Plus1>>>&

  FilterFrequencyResponses() const {

    return refined_frequency_responses_;

  // Returns the estimates of the impulse responses for the refined adaptive

  // filters.

  const std::vector<std::vector<float>>& FilterImpulseResponses() const {

    return refined_impulse_responses_;

  void DumpFilters() {

    data_dumper_->DumpRaw(

        "aec3_subtractor_h_refined",

        rtc::ArrayView<const float>(

            refined_impulse_responses_[0].data(),

            GetTimeDomainLength(

                refined_filters_[0]->max_filter_size_partitions())));

    if (ApmDataDumper::IsAvailable()) {

      RTC_DCHECK_GT(coarse_impulse_responses_.size(), 0);

      data_dumper_->DumpRaw(

          "aec3_subtractor_h_coarse",

          rtc::ArrayView<const float>(

              coarse_impulse_responses_[0].data(),

              GetTimeDomainLength(

                  coarse_filter_[0]->max_filter_size_partitions())));

    refined_filters_[0]->DumpFilter("aec3_subtractor_H_refined");

    coarse_filter_[0]->DumpFilter("aec3_subtractor_H_coarse");

 private:

  class FilterMisadjustmentEstimator {

   public:

    FilterMisadjustmentEstimator() = default;

    ~FilterMisadjustmentEstimator() = default;

    // Update the misadjustment estimator.

    void Update(const SubtractorOutput& output);

    // GetMisadjustment() Returns a recommended scale for the filter so the

    // prediction error energy gets closer to the energy that is seen at the

    // microphone input.

    float GetMisadjustment() const {

      RTC_DCHECK_GT(inv_misadjustment_, 0.0f);

      // It is not aiming to adjust all the estimated mismatch. Instead,

      // it adjusts half of that estimated mismatch.

      return 2.f / sqrtf(inv_misadjustment_);

    // Returns true if the prediciton error energy is significantly larger

    // than the microphone signal energy and, therefore, an adjustment is

    // recommended.

    bool IsAdjustmentNeeded() const { return inv_misadjustment_ > 10.f; }

    void Reset();

    void Dump(ApmDataDumper* data_dumper) const;

   private:

    const int n_blocks_ = 4;

    int n_blocks_acum_ = 0;

    float e2_acum_ = 0.f;

    float y2_acum_ = 0.f;

    float inv_misadjustment_ = 0.f;

    int overhang_ = 0.f;

};

  const Aec3Fft fft_;

  ApmDataDumper* data_dumper_;

  const Aec3Optimization optimization_;

  const EchoCanceller3Config config_;

  const size_t num_capture_channels_;

  const bool use_coarse_filter_reset_hangover_;

  std::vector<std::unique_ptr<AdaptiveFirFilter>> refined_filters_;

  std::vector<std::unique_ptr<AdaptiveFirFilter>> coarse_filter_;

  std::vector<std::unique_ptr<RefinedFilterUpdateGain>> refined_gains_;

  std::vector<std::unique_ptr<CoarseFilterUpdateGain>> coarse_gains_;

  std::vector<FilterMisadjustmentEstimator> filter_misadjustment_estimators_;

  std::vector<size_t> poor_coarse_filter_counters_;

  std::vector<int> coarse_filter_reset_hangover_;

  std::vector<std::vector<std::array<float, kFftLengthBy2Plus1>>>

      refined_frequency_responses_;

  std::vector<std::vector<float>> refined_impulse_responses_;

  std::vector<std::vector<float>> coarse_impulse_responses_;

};

}  // namespace webrtc

#endif  // MODULES_AUDIO_PROCESSING_AEC3_SUBTRACTOR_H_