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 #include "modules/audio_processing/agc/loudness_histogram.h"
12
13 #include <string.h>
14
15 #include <cmath>
16
17 #include "rtc_base/checks.h"
18
19 namespace webrtc {
20
21 static const double kHistBinCenters[] = {
22 7.59621091765857e-02, 9.02036021061016e-02, 1.07115112009343e-01,
23 1.27197217770508e-01, 1.51044347572047e-01, 1.79362373905283e-01,
24 2.12989507320644e-01, 2.52921107370304e-01, 3.00339145144454e-01,
25 3.56647189489147e-01, 4.23511952494003e-01, 5.02912623991786e-01,
26 5.97199455365749e-01, 7.09163326739184e-01, 8.42118356728544e-01,
27 1.00000000000000e+00, 1.18748153630660e+00, 1.41011239906908e+00,
28 1.67448243801153e+00, 1.98841697800836e+00, 2.36120844786349e+00,
29 2.80389143520905e+00, 3.32956930911896e+00, 3.95380207843188e+00,
30 4.69506696634852e+00, 5.57530533426190e+00, 6.62057214370769e+00,
31 7.86180718043869e+00, 9.33575086877358e+00, 1.10860317842269e+01,
32 1.31644580546776e+01, 1.56325508754123e+01, 1.85633655299256e+01,
33 2.20436538184971e+01, 2.61764319021997e+01, 3.10840295702492e+01,
34 3.69117111886792e+01, 4.38319755100383e+01, 5.20496616180135e+01,
35 6.18080121423973e+01, 7.33958732149108e+01, 8.71562442838066e+01,
36 1.03496430860848e+02, 1.22900100720889e+02, 1.45941600416277e+02,
37 1.73302955873365e+02, 2.05794060286978e+02, 2.44376646872353e+02,
38 2.90192756065437e+02, 3.44598539797631e+02, 4.09204403447902e+02,
39 4.85922673669740e+02, 5.77024203055553e+02, 6.85205587130498e+02,
40 8.13668983291589e+02, 9.66216894324125e+02, 1.14736472207740e+03,
41 1.36247442287647e+03, 1.61791322085579e+03, 1.92124207711260e+03,
42 2.28143949334655e+03, 2.70916727454970e+03, 3.21708611729384e+03,
43 3.82023036499473e+03, 4.53645302286906e+03, 5.38695420497926e+03,
44 6.39690865534207e+03, 7.59621091765857e+03, 9.02036021061016e+03,
45 1.07115112009343e+04, 1.27197217770508e+04, 1.51044347572047e+04,
46 1.79362373905283e+04, 2.12989507320644e+04, 2.52921107370304e+04,
47 3.00339145144454e+04, 3.56647189489147e+04};
48
49 static const double kProbQDomain = 1024.0;
50 // Loudness of -15 dB (smallest expected loudness) in log domain,
51 // loudness_db = 13.5 * log10(rms);
52 static const double kLogDomainMinBinCenter = -2.57752062648587;
53 // Loudness step of 1 dB in log domain
54 static const double kLogDomainStepSizeInverse = 5.81954605750359;
55
56 static const int kTransientWidthThreshold = 7;
57 static const double kLowProbabilityThreshold = 0.2;
58
59 static const int kLowProbThresholdQ10 =
60 static_cast<int>(kLowProbabilityThreshold * kProbQDomain);
61
LoudnessHistogram()62 LoudnessHistogram::LoudnessHistogram()
63 : num_updates_(0),
64 audio_content_q10_(0),
65 bin_count_q10_(),
66 activity_probability_(),
67 hist_bin_index_(),
68 buffer_index_(0),
69 buffer_is_full_(false),
70 len_circular_buffer_(0),
71 len_high_activity_(0) {
72 static_assert(
73 kHistSize == sizeof(kHistBinCenters) / sizeof(kHistBinCenters[0]),
74 "histogram bin centers incorrect size");
75 }
76
LoudnessHistogram(int window_size)77 LoudnessHistogram::LoudnessHistogram(int window_size)
78 : num_updates_(0),
79 audio_content_q10_(0),
80 bin_count_q10_(),
81 activity_probability_(new int[window_size]),
82 hist_bin_index_(new int[window_size]),
83 buffer_index_(0),
84 buffer_is_full_(false),
85 len_circular_buffer_(window_size),
86 len_high_activity_(0) {}
87
~LoudnessHistogram()88 LoudnessHistogram::~LoudnessHistogram() {}
89
Update(double rms,double activity_probaility)90 void LoudnessHistogram::Update(double rms, double activity_probaility) {
91 // If circular histogram is activated then remove the oldest entry.
92 if (len_circular_buffer_ > 0)
93 RemoveOldestEntryAndUpdate();
94
95 // Find the corresponding bin.
96 int hist_index = GetBinIndex(rms);
97 // To Q10 domain.
98 int prob_q10 =
99 static_cast<int16_t>(floor(activity_probaility * kProbQDomain));
100 InsertNewestEntryAndUpdate(prob_q10, hist_index);
101 }
102
103 // Doing nothing if buffer is not full, yet.
RemoveOldestEntryAndUpdate()104 void LoudnessHistogram::RemoveOldestEntryAndUpdate() {
105 RTC_DCHECK_GT(len_circular_buffer_, 0);
106 // Do nothing if circular buffer is not full.
107 if (!buffer_is_full_)
108 return;
109
110 int oldest_prob = activity_probability_[buffer_index_];
111 int oldest_hist_index = hist_bin_index_[buffer_index_];
112 UpdateHist(-oldest_prob, oldest_hist_index);
113 }
114
RemoveTransient()115 void LoudnessHistogram::RemoveTransient() {
116 // Don't expect to be here if high-activity region is longer than
117 // |kTransientWidthThreshold| or there has not been any transient.
118 RTC_DCHECK_LE(len_high_activity_, kTransientWidthThreshold);
119 int index =
120 (buffer_index_ > 0) ? (buffer_index_ - 1) : len_circular_buffer_ - 1;
121 while (len_high_activity_ > 0) {
122 UpdateHist(-activity_probability_[index], hist_bin_index_[index]);
123 activity_probability_[index] = 0;
124 index = (index > 0) ? (index - 1) : (len_circular_buffer_ - 1);
125 len_high_activity_--;
126 }
127 }
128
InsertNewestEntryAndUpdate(int activity_prob_q10,int hist_index)129 void LoudnessHistogram::InsertNewestEntryAndUpdate(int activity_prob_q10,
130 int hist_index) {
131 // Update the circular buffer if it is enabled.
132 if (len_circular_buffer_ > 0) {
133 // Removing transient.
134 if (activity_prob_q10 <= kLowProbThresholdQ10) {
135 // Lower than threshold probability, set it to zero.
136 activity_prob_q10 = 0;
137 // Check if this has been a transient.
138 if (len_high_activity_ <= kTransientWidthThreshold)
139 RemoveTransient(); // Remove this transient.
140 len_high_activity_ = 0;
141 } else if (len_high_activity_ <= kTransientWidthThreshold) {
142 len_high_activity_++;
143 }
144 // Updating the circular buffer.
145 activity_probability_[buffer_index_] = activity_prob_q10;
146 hist_bin_index_[buffer_index_] = hist_index;
147 // Increment the buffer index and check for wrap-around.
148 buffer_index_++;
149 if (buffer_index_ >= len_circular_buffer_) {
150 buffer_index_ = 0;
151 buffer_is_full_ = true;
152 }
153 }
154
155 num_updates_++;
156 if (num_updates_ < 0)
157 num_updates_--;
158
159 UpdateHist(activity_prob_q10, hist_index);
160 }
161
UpdateHist(int activity_prob_q10,int hist_index)162 void LoudnessHistogram::UpdateHist(int activity_prob_q10, int hist_index) {
163 bin_count_q10_[hist_index] += activity_prob_q10;
164 audio_content_q10_ += activity_prob_q10;
165 }
166
AudioContent() const167 double LoudnessHistogram::AudioContent() const {
168 return audio_content_q10_ / kProbQDomain;
169 }
170
Create()171 LoudnessHistogram* LoudnessHistogram::Create() {
172 return new LoudnessHistogram;
173 }
174
Create(int window_size)175 LoudnessHistogram* LoudnessHistogram::Create(int window_size) {
176 if (window_size < 0)
177 return NULL;
178 return new LoudnessHistogram(window_size);
179 }
180
Reset()181 void LoudnessHistogram::Reset() {
182 // Reset the histogram, audio-content and number of updates.
183 memset(bin_count_q10_, 0, sizeof(bin_count_q10_));
184 audio_content_q10_ = 0;
185 num_updates_ = 0;
186 // Empty the circular buffer.
187 buffer_index_ = 0;
188 buffer_is_full_ = false;
189 len_high_activity_ = 0;
190 }
191
GetBinIndex(double rms)192 int LoudnessHistogram::GetBinIndex(double rms) {
193 // First exclude overload cases.
194 if (rms <= kHistBinCenters[0]) {
195 return 0;
196 } else if (rms >= kHistBinCenters[kHistSize - 1]) {
197 return kHistSize - 1;
198 } else {
199 // The quantizer is uniform in log domain. Alternatively we could do binary
200 // search in linear domain.
201 double rms_log = log(rms);
202
203 int index = static_cast<int>(
204 floor((rms_log - kLogDomainMinBinCenter) * kLogDomainStepSizeInverse));
205 // The final decision is in linear domain.
206 double b = 0.5 * (kHistBinCenters[index] + kHistBinCenters[index + 1]);
207 if (rms > b) {
208 return index + 1;
209 }
210 return index;
211 }
212 }
213
CurrentRms() const214 double LoudnessHistogram::CurrentRms() const {
215 double p;
216 double mean_val = 0;
217 if (audio_content_q10_ > 0) {
218 double p_total_inverse = 1. / static_cast<double>(audio_content_q10_);
219 for (int n = 0; n < kHistSize; n++) {
220 p = static_cast<double>(bin_count_q10_[n]) * p_total_inverse;
221 mean_val += p * kHistBinCenters[n];
222 }
223 } else {
224 mean_val = kHistBinCenters[0];
225 }
226 return mean_val;
227 }
228
229 } // namespace webrtc
230