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loudness_histogram.h (3010B)

      1 /*
      2 *  Copyright (c) 2012 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_AGC_LOUDNESS_HISTOGRAM_H_
     12 #define MODULES_AUDIO_PROCESSING_AGC_LOUDNESS_HISTOGRAM_H_
     13 
     14 #include <stdint.h>
     15 
     16 #include <memory>
     17 
     18 namespace webrtc {
     19 
     20 // This class implements the histogram of loudness with circular buffers so that
     21 // the histogram tracks the last T seconds of the loudness.
     22 class LoudnessHistogram {
     23 public:
     24  // Create a non-sliding LoudnessHistogram.
     25  static LoudnessHistogram* Create();
     26 
     27  // Create a sliding LoudnessHistogram, i.e. the histogram represents the last
     28  // `window_size` samples.
     29  static LoudnessHistogram* Create(int window_size);
     30  ~LoudnessHistogram();
     31 
     32  // Insert RMS and the corresponding activity probability.
     33  void Update(double rms, double activity_probability);
     34 
     35  // Reset the histogram, forget the past.
     36  void Reset();
     37 
     38  // Current loudness, which is actually the mean of histogram in loudness
     39  // domain.
     40  double CurrentRms() const;
     41 
     42  // Sum of the histogram content.
     43  double AudioContent() const;
     44 
     45  // Number of times the histogram has been updated.
     46  int num_updates() const { return num_updates_; }
     47 
     48 private:
     49  LoudnessHistogram();
     50  explicit LoudnessHistogram(int window);
     51 
     52  // Find the histogram bin associated with the given `rms`.
     53  int GetBinIndex(double rms);
     54 
     55  void RemoveOldestEntryAndUpdate();
     56  void InsertNewestEntryAndUpdate(int activity_prob_q10, int hist_index);
     57  void UpdateHist(int activity_prob_q10, int hist_index);
     58  void RemoveTransient();
     59 
     60  // Number of histogram bins.
     61  static const int kHistSize = 77;
     62 
     63  // Number of times the histogram is updated
     64  int num_updates_;
     65  // Audio content, this should be equal to the sum of the components of
     66  // `bin_count_q10_`.
     67  int64_t audio_content_q10_;
     68 
     69  // LoudnessHistogram of input RMS in Q10 with `kHistSize_` bins. In each
     70  // 'Update(),' we increment the associated histogram-bin with the given
     71  // probability. The increment is implemented in Q10 to avoid rounding errors.
     72  int64_t bin_count_q10_[kHistSize];
     73 
     74  // Circular buffer for probabilities
     75  std::unique_ptr<int[]> activity_probability_;
     76  // Circular buffer for histogram-indices of probabilities.
     77  std::unique_ptr<int[]> hist_bin_index_;
     78  // Current index of circular buffer, where the newest data will be written to,
     79  // therefore, pointing to the oldest data if buffer is full.
     80  int buffer_index_;
     81  // Indicating if buffer is full and we had a wrap around.
     82  int buffer_is_full_;
     83  // Size of circular buffer.
     84  int len_circular_buffer_;
     85  int len_high_activity_;
     86 };
     87 
     88 }  // namespace webrtc
     89 
     90 #endif  // MODULES_AUDIO_PROCESSING_AGC_LOUDNESS_HISTOGRAM_H_