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* Copyright (c) 2012 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.
#include <stdint.h>
#include <memory>
namespace webrtc {
// This class implements the histogram of loudness with circular buffers so that
// the histogram tracks the last T seconds of the loudness.
class LoudnessHistogram {
// Create a non-sliding LoudnessHistogram.
static LoudnessHistogram* Create();
// Create a sliding LoudnessHistogram, i.e. the histogram represents the last
// `window_size` samples.
static LoudnessHistogram* Create(int window_size);
// Insert RMS and the corresponding activity probability.
void Update(double rms, double activity_probability);
// Reset the histogram, forget the past.
void Reset();
// Current loudness, which is actually the mean of histogram in loudness
// domain.
double CurrentRms() const;
// Sum of the histogram content.
double AudioContent() const;
// Number of times the histogram has been updated.
int num_updates() const { return num_updates_; }
explicit LoudnessHistogram(int window);
// Find the histogram bin associated with the given `rms`.
int GetBinIndex(double rms);
void RemoveOldestEntryAndUpdate();
void InsertNewestEntryAndUpdate(int activity_prob_q10, int hist_index);
void UpdateHist(int activity_prob_q10, int hist_index);
void RemoveTransient();
// Number of histogram bins.
static const int kHistSize = 77;
// Number of times the histogram is updated
int num_updates_;
// Audio content, this should be equal to the sum of the components of
// `bin_count_q10_`.
int64_t audio_content_q10_;
// LoudnessHistogram of input RMS in Q10 with `kHistSize_` bins. In each
// 'Update(),' we increment the associated histogram-bin with the given
// probability. The increment is implemented in Q10 to avoid rounding errors.
int64_t bin_count_q10_[kHistSize];
// Circular buffer for probabilities
std::unique_ptr<int[]> activity_probability_;
// Circular buffer for histogram-indices of probabilities.
std::unique_ptr<int[]> hist_bin_index_;
// Current index of circular buffer, where the newest data will be written to,
// therefore, pointing to the oldest data if buffer is full.
int buffer_index_;
// Indicating if buffer is full and we had a wrap around.
int buffer_is_full_;
// Size of circular buffer.
int len_circular_buffer_;
int len_high_activity_;
} // namespace webrtc