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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 "modules/audio_processing/agc/loudness_histogram.h"
#include <string.h>
#include <cmath>
#include "rtc_base/checks.h"
namespace webrtc {
static const double kHistBinCenters[] = {
7.59621091765857e-02, 9.02036021061016e-02, 1.07115112009343e-01,
1.27197217770508e-01, 1.51044347572047e-01, 1.79362373905283e-01,
2.12989507320644e-01, 2.52921107370304e-01, 3.00339145144454e-01,
3.56647189489147e-01, 4.23511952494003e-01, 5.02912623991786e-01,
5.97199455365749e-01, 7.09163326739184e-01, 8.42118356728544e-01,
1.00000000000000e+00, 1.18748153630660e+00, 1.41011239906908e+00,
1.67448243801153e+00, 1.98841697800836e+00, 2.36120844786349e+00,
2.80389143520905e+00, 3.32956930911896e+00, 3.95380207843188e+00,
4.69506696634852e+00, 5.57530533426190e+00, 6.62057214370769e+00,
7.86180718043869e+00, 9.33575086877358e+00, 1.10860317842269e+01,
1.31644580546776e+01, 1.56325508754123e+01, 1.85633655299256e+01,
2.20436538184971e+01, 2.61764319021997e+01, 3.10840295702492e+01,
3.69117111886792e+01, 4.38319755100383e+01, 5.20496616180135e+01,
6.18080121423973e+01, 7.33958732149108e+01, 8.71562442838066e+01,
1.03496430860848e+02, 1.22900100720889e+02, 1.45941600416277e+02,
1.73302955873365e+02, 2.05794060286978e+02, 2.44376646872353e+02,
2.90192756065437e+02, 3.44598539797631e+02, 4.09204403447902e+02,
4.85922673669740e+02, 5.77024203055553e+02, 6.85205587130498e+02,
8.13668983291589e+02, 9.66216894324125e+02, 1.14736472207740e+03,
1.36247442287647e+03, 1.61791322085579e+03, 1.92124207711260e+03,
2.28143949334655e+03, 2.70916727454970e+03, 3.21708611729384e+03,
3.82023036499473e+03, 4.53645302286906e+03, 5.38695420497926e+03,
6.39690865534207e+03, 7.59621091765857e+03, 9.02036021061016e+03,
1.07115112009343e+04, 1.27197217770508e+04, 1.51044347572047e+04,
1.79362373905283e+04, 2.12989507320644e+04, 2.52921107370304e+04,
3.00339145144454e+04, 3.56647189489147e+04};
static const double kProbQDomain = 1024.0;
// Loudness of -15 dB (smallest expected loudness) in log domain,
// loudness_db = 13.5 * log10(rms);
static const double kLogDomainMinBinCenter = -2.57752062648587;
// Loudness step of 1 dB in log domain
static const double kLogDomainStepSizeInverse = 5.81954605750359;
static const int kTransientWidthThreshold = 7;
static const double kLowProbabilityThreshold = 0.2;
static const int kLowProbThresholdQ10 =
static_cast<int>(kLowProbabilityThreshold * kProbQDomain);
LoudnessHistogram::LoudnessHistogram()
: num_updates_(0),
audio_content_q10_(0),
bin_count_q10_(),
activity_probability_(),
hist_bin_index_(),
buffer_index_(0),
buffer_is_full_(false),
len_circular_buffer_(0),
len_high_activity_(0) {
static_assert(
kHistSize == sizeof(kHistBinCenters) / sizeof(kHistBinCenters[0]),
"histogram bin centers incorrect size");
}
LoudnessHistogram::LoudnessHistogram(int window_size)
: num_updates_(0),
audio_content_q10_(0),
bin_count_q10_(),
activity_probability_(new int[window_size]),
hist_bin_index_(new int[window_size]),
buffer_index_(0),
buffer_is_full_(false),
len_circular_buffer_(window_size),
len_high_activity_(0) {}
LoudnessHistogram::~LoudnessHistogram() {}
void LoudnessHistogram::Update(double rms, double activity_probaility) {
// If circular histogram is activated then remove the oldest entry.
if (len_circular_buffer_ > 0)
RemoveOldestEntryAndUpdate();
// Find the corresponding bin.
int hist_index = GetBinIndex(rms);
// To Q10 domain.
int prob_q10 =
static_cast<int16_t>(floor(activity_probaility * kProbQDomain));
InsertNewestEntryAndUpdate(prob_q10, hist_index);
}
// Doing nothing if buffer is not full, yet.
void LoudnessHistogram::RemoveOldestEntryAndUpdate() {
RTC_DCHECK_GT(len_circular_buffer_, 0);
// Do nothing if circular buffer is not full.
if (!buffer_is_full_)
return;
int oldest_prob = activity_probability_[buffer_index_];
int oldest_hist_index = hist_bin_index_[buffer_index_];
UpdateHist(-oldest_prob, oldest_hist_index);
}
void LoudnessHistogram::RemoveTransient() {
// Don't expect to be here if high-activity region is longer than
// `kTransientWidthThreshold` or there has not been any transient.
RTC_DCHECK_LE(len_high_activity_, kTransientWidthThreshold);
int index =
(buffer_index_ > 0) ? (buffer_index_ - 1) : len_circular_buffer_ - 1;
while (len_high_activity_ > 0) {
UpdateHist(-activity_probability_[index], hist_bin_index_[index]);
activity_probability_[index] = 0;
index = (index > 0) ? (index - 1) : (len_circular_buffer_ - 1);
len_high_activity_--;
}
}
void LoudnessHistogram::InsertNewestEntryAndUpdate(int activity_prob_q10,
int hist_index) {
// Update the circular buffer if it is enabled.
if (len_circular_buffer_ > 0) {
// Removing transient.
if (activity_prob_q10 <= kLowProbThresholdQ10) {
// Lower than threshold probability, set it to zero.
activity_prob_q10 = 0;
// Check if this has been a transient.
if (len_high_activity_ <= kTransientWidthThreshold)
RemoveTransient(); // Remove this transient.
len_high_activity_ = 0;
} else if (len_high_activity_ <= kTransientWidthThreshold) {
len_high_activity_++;
}
// Updating the circular buffer.
activity_probability_[buffer_index_] = activity_prob_q10;
hist_bin_index_[buffer_index_] = hist_index;
// Increment the buffer index and check for wrap-around.
buffer_index_++;
if (buffer_index_ >= len_circular_buffer_) {
buffer_index_ = 0;
buffer_is_full_ = true;
}
}
num_updates_++;
if (num_updates_ < 0)
num_updates_--;
UpdateHist(activity_prob_q10, hist_index);
}
void LoudnessHistogram::UpdateHist(int activity_prob_q10, int hist_index) {
bin_count_q10_[hist_index] += activity_prob_q10;
audio_content_q10_ += activity_prob_q10;
}
double LoudnessHistogram::AudioContent() const {
return audio_content_q10_ / kProbQDomain;
}
LoudnessHistogram* LoudnessHistogram::Create() {
return new LoudnessHistogram;
}
LoudnessHistogram* LoudnessHistogram::Create(int window_size) {
if (window_size < 0)
return NULL;
return new LoudnessHistogram(window_size);
}
void LoudnessHistogram::Reset() {
// Reset the histogram, audio-content and number of updates.
memset(bin_count_q10_, 0, sizeof(bin_count_q10_));
audio_content_q10_ = 0;
num_updates_ = 0;
// Empty the circular buffer.
buffer_index_ = 0;
buffer_is_full_ = false;
len_high_activity_ = 0;
}
int LoudnessHistogram::GetBinIndex(double rms) {
// First exclude overload cases.
if (rms <= kHistBinCenters[0]) {
return 0;
} else if (rms >= kHistBinCenters[kHistSize - 1]) {
return kHistSize - 1;
} else {
// The quantizer is uniform in log domain. Alternatively we could do binary
// search in linear domain.
double rms_log = log(rms);
int index = static_cast<int>(
floor((rms_log - kLogDomainMinBinCenter) * kLogDomainStepSizeInverse));
// The final decision is in linear domain.
double b = 0.5 * (kHistBinCenters[index] + kHistBinCenters[index + 1]);
if (rms > b) {
return index + 1;
}
return index;
}
}
double LoudnessHistogram::CurrentRms() const {
double p;
double mean_val = 0;
if (audio_content_q10_ > 0) {
double p_total_inverse = 1. / static_cast<double>(audio_content_q10_);
for (int n = 0; n < kHistSize; n++) {
p = static_cast<double>(bin_count_q10_[n]) * p_total_inverse;
mean_val += p * kHistBinCenters[n];
}
} else {
mean_val = kHistBinCenters[0];
}
return mean_val;
}
} // namespace webrtc
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