text: /*
   *  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_AEC_STATE_H_
  #define MODULES_AUDIO_PROCESSING_AEC3_AEC_STATE_H_
  
  #include <algorithm>
  #include <memory>
  #include <vector>
  
  #include "api/array_view.h"
  #include "api/optional.h"
  #include "modules/audio_processing/aec3/aec3_common.h"
  #include "modules/audio_processing/aec3/echo_path_variability.h"
  #include "modules/audio_processing/aec3/erl_estimator.h"
  #include "modules/audio_processing/aec3/erle_estimator.h"
  #include "modules/audio_processing/aec3/render_buffer.h"
  #include "modules/audio_processing/include/audio_processing.h"
  #include "rtc_base/constructormagic.h"
  
  namespace webrtc {
  
  class ApmDataDumper;
  
  // Handles the state and the conditions for the echo removal functionality.
  class AecState {
   public:
    explicit AecState(const AudioProcessing::Config::EchoCanceller3& config);
    ~AecState();
  
    // Returns whether the linear filter estimate is usable.
    bool UsableLinearEstimate() const { return usable_linear_estimate_; }
  
    // Returns whether there has been echo leakage detected.
    bool EchoLeakageDetected() const { return echo_leakage_detected_; }
  
    // Returns whether the render signal is currently active.
    // TODO(peah): Deprecate this in an upcoming CL.
    bool ActiveRender() const { return blocks_with_filter_adaptation_ > 200; }
  
    // Returns the ERLE.
    const std::array<float, kFftLengthBy2Plus1>& Erle() const {
      return erle_estimator_.Erle();
    }
  
    // Returns the ERL.
    const std::array<float, kFftLengthBy2Plus1>& Erl() const {
      return erl_estimator_.Erl();
    }
  
    // Returns the delay estimate based on the linear filter.
    rtc::Optional<size_t> FilterDelay() const { return filter_delay_; }
  
    // Returns the externally provided delay.
    rtc::Optional<size_t> ExternalDelay() const { return external_delay_; }
  
    // Returns whether the capture signal is saturated.
    bool SaturatedCapture() const { return capture_signal_saturation_; }
  
    // Returns whether the echo signal is saturated.
    bool SaturatedEcho() const { return echo_saturation_; }
  
    // Updates the capture signal saturation.
    void UpdateCaptureSaturation(bool capture_signal_saturation) {
      capture_signal_saturation_ = capture_signal_saturation;
    }
  
    // Returns whether the transparent mode is active
    bool TransparentMode() const { return transparent_mode_; }
  
    // Takes appropriate action at an echo path change.
    void HandleEchoPathChange(const EchoPathVariability& echo_path_variability);
  
    // Returns the decay factor for the echo reverberation.
    float ReverbDecay() const { return reverb_decay_; }
  
    // Returns whether the echo suppression gain should be forced to zero.
    bool ForcedZeroGain() const { return force_zero_gain_; }
  
    // Returns whether the echo in the capture signal is audible.
    bool InaudibleEcho() const { return echo_audibility_.InaudibleEcho(); }
  
    // Updates the aec state with the AEC output signal.
    void UpdateWithOutput(rtc::ArrayView<const float> e) {
      echo_audibility_.UpdateWithOutput(e);
    }
  
    // Returns whether the linear filter should have been able to adapt properly.
    bool SufficientFilterUpdates() const {
      return blocks_with_filter_adaptation_ >= kEchoPathChangeConvergenceBlocks;
    }
  
    // Returns whether the echo subtractor can be used to determine the residual
    // echo.
    bool LinearEchoEstimate() const {
      return UsableLinearEstimate() && !TransparentMode();
    }
  
    // Returns whether the AEC is in an initial state.
    bool InitialState() const {
      return capture_block_counter_ < 3 * kNumBlocksPerSecond;
    }
  
    // Updates the aec state.
    void Update(const std::vector<std::array<float, kFftLengthBy2Plus1>>&
                    adaptive_filter_frequency_response,
                const std::array<float, kAdaptiveFilterTimeDomainLength>&
                    adaptive_filter_impulse_response,
                bool converged_filter,
                const rtc::Optional<size_t>& external_delay_samples,
                const RenderBuffer& render_buffer,
                const std::array<float, kFftLengthBy2Plus1>& E2_main,
                const std::array<float, kFftLengthBy2Plus1>& Y2,
                rtc::ArrayView<const float> x,
                const std::array<float, kBlockSize>& s_main,
                bool echo_leakage_detected);
  
   private:
    class EchoAudibility {
     public:
      void Update(rtc::ArrayView<const float> x,
                  const std::array<float, kBlockSize>& s,
                  bool converged_filter);
      void UpdateWithOutput(rtc::ArrayView<const float> e);
      bool InaudibleEcho() const { return inaudible_echo_; }
  
     private:
      float max_nearend_ = 0.f;
      size_t max_nearend_counter_ = 0;
      size_t low_farend_counter_ = 0;
      bool inaudible_echo_ = false;
    };
  
    void UpdateReverb(const std::array<float, kAdaptiveFilterTimeDomainLength>&
                          impulse_response);
  
    static int instance_count_;
    std::unique_ptr<ApmDataDumper> data_dumper_;
    ErlEstimator erl_estimator_;
    ErleEstimator erle_estimator_;
    size_t capture_block_counter_ = 0;
    size_t blocks_with_filter_adaptation_ = 0;
    bool usable_linear_estimate_ = false;
    bool echo_leakage_detected_ = false;
    bool capture_signal_saturation_ = false;
    bool echo_saturation_ = false;
    bool transparent_mode_ = false;
    float previous_max_sample_ = 0.f;
    bool force_zero_gain_ = false;
    bool render_received_ = false;
    size_t force_zero_gain_counter_ = 0;
    rtc::Optional<size_t> filter_delay_;
    rtc::Optional<size_t> external_delay_;
    size_t blocks_since_last_saturation_ = 1000;
    float reverb_decay_to_test_ = 0.9f;
    float reverb_decay_candidate_ = 0.f;
    float reverb_decay_candidate_residual_ = -1.f;
    EchoAudibility echo_audibility_;
    const AudioProcessing::Config::EchoCanceller3 config_;
    float reverb_decay_;
  
    RTC_DISALLOW_COPY_AND_ASSIGN(AecState);
  };
  
  }  // namespace webrtc
  
  #endif  // MODULES_AUDIO_PROCESSING_AEC3_AEC_STATE_H_
  