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reverb_decay_estimator.h (3738B)

      1 /*
      2 *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
      3 *
      4 *  Use of this source code is governed by a BSD-style license
      5 *  that can be found in the LICENSE file in the root of the source
      6 *  tree. An additional intellectual property rights grant can be found
      7 *  in the file PATENTS.  All contributing project authors may
      8 *  be found in the AUTHORS file in the root of the source tree.
      9 */
     10 
     11 #ifndef MODULES_AUDIO_PROCESSING_AEC3_REVERB_DECAY_ESTIMATOR_H_
     12 #define MODULES_AUDIO_PROCESSING_AEC3_REVERB_DECAY_ESTIMATOR_H_
     13 
     14 #include <optional>
     15 #include <vector>
     16 
     17 #include "api/array_view.h"
     18 
     19 namespace webrtc {
     20 
     21 class ApmDataDumper;
     22 struct EchoCanceller3Config;
     23 
     24 // Class for estimating the decay of the late reverb.
     25 class ReverbDecayEstimator {
     26 public:
     27  explicit ReverbDecayEstimator(const EchoCanceller3Config& config);
     28  ~ReverbDecayEstimator();
     29  // Updates the decay estimate.
     30  void Update(ArrayView<const float> filter,
     31              const std::optional<float>& filter_quality,
     32              int filter_delay_blocks,
     33              bool usable_linear_filter,
     34              bool stationary_signal);
     35  // Returns the decay for the exponential model. The parameter `mild` indicates
     36  // which exponential decay to return, the default one or a milder one.
     37  float Decay(bool mild) const {
     38    if (use_adaptive_echo_decay_) {
     39      return decay_;
     40    } else {
     41      return mild ? mild_decay_ : decay_;
     42    }
     43  }
     44  // Dumps debug data.
     45  void Dump(ApmDataDumper* data_dumper) const;
     46 
     47 private:
     48  void EstimateDecay(ArrayView<const float> filter, int peak_block);
     49  void AnalyzeFilter(ArrayView<const float> filter);
     50 
     51  void ResetDecayEstimation();
     52 
     53  // Class for estimating the decay of the late reverb from the linear filter.
     54  class LateReverbLinearRegressor {
     55   public:
     56    // Resets the estimator to receive a specified number of data points.
     57    void Reset(int num_data_points);
     58    // Accumulates estimation data.
     59    void Accumulate(float z);
     60    // Estimates the decay.
     61    float Estimate();
     62    // Returns whether an estimate is available.
     63    bool EstimateAvailable() const { return n_ == N_ && N_ != 0; }
     64 
     65   public:
     66    float nz_ = 0.f;
     67    float nn_ = 0.f;
     68    float count_ = 0.f;
     69    int N_ = 0;
     70    int n_ = 0;
     71  };
     72 
     73  // Class for identifying the length of the early reverb from the linear
     74  // filter. For identifying the early reverberations, the impulse response is
     75  // divided in sections and the tilt of each section is computed by a linear
     76  // regressor.
     77  class EarlyReverbLengthEstimator {
     78   public:
     79    explicit EarlyReverbLengthEstimator(int max_blocks);
     80    ~EarlyReverbLengthEstimator();
     81 
     82    // Resets the estimator.
     83    void Reset();
     84    // Accumulates estimation data.
     85    void Accumulate(float value, float smoothing);
     86    // Estimates the size in blocks of the early reverb.
     87    int Estimate();
     88    // Dumps debug data.
     89    void Dump(ApmDataDumper* data_dumper) const;
     90 
     91   private:
     92    std::vector<float> numerators_smooth_;
     93    std::vector<float> numerators_;
     94    int coefficients_counter_;
     95    int block_counter_ = 0;
     96    int n_sections_ = 0;
     97  };
     98 
     99  const int filter_length_blocks_;
    100  const int filter_length_coefficients_;
    101  const bool use_adaptive_echo_decay_;
    102  LateReverbLinearRegressor late_reverb_decay_estimator_;
    103  EarlyReverbLengthEstimator early_reverb_estimator_;
    104  int late_reverb_start_;
    105  int late_reverb_end_;
    106  int block_to_analyze_ = 0;
    107  int estimation_region_candidate_size_ = 0;
    108  bool estimation_region_identified_ = false;
    109  std::vector<float> previous_gains_;
    110  float decay_;
    111  float mild_decay_;
    112  float tail_gain_ = 0.f;
    113  float smoothing_constant_ = 0.f;
    114 };
    115 
    116 }  // namespace webrtc
    117 
    118 #endif  // MODULES_AUDIO_PROCESSING_AEC3_REVERB_DECAY_ESTIMATOR_H_