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 "webrtc/modules/audio_processing/agc/histogram.h"
12
13 #include <cmath>
14 #include <cstring>
15
16 #include "webrtc/modules/include/module_common_types.h"
17
18 namespace webrtc {
19
20 static const double kHistBinCenters[] = {
21 7.59621091765857e-02, 9.02036021061016e-02, 1.07115112009343e-01,
22 1.27197217770508e-01, 1.51044347572047e-01, 1.79362373905283e-01,
23 2.12989507320644e-01, 2.52921107370304e-01, 3.00339145144454e-01,
24 3.56647189489147e-01, 4.23511952494003e-01, 5.02912623991786e-01,
25 5.97199455365749e-01, 7.09163326739184e-01, 8.42118356728544e-01,
26 1.00000000000000e+00, 1.18748153630660e+00, 1.41011239906908e+00,
27 1.67448243801153e+00, 1.98841697800836e+00, 2.36120844786349e+00,
28 2.80389143520905e+00, 3.32956930911896e+00, 3.95380207843188e+00,
29 4.69506696634852e+00, 5.57530533426190e+00, 6.62057214370769e+00,
30 7.86180718043869e+00, 9.33575086877358e+00, 1.10860317842269e+01,
31 1.31644580546776e+01, 1.56325508754123e+01, 1.85633655299256e+01,
32 2.20436538184971e+01, 2.61764319021997e+01, 3.10840295702492e+01,
33 3.69117111886792e+01, 4.38319755100383e+01, 5.20496616180135e+01,
34 6.18080121423973e+01, 7.33958732149108e+01, 8.71562442838066e+01,
35 1.03496430860848e+02, 1.22900100720889e+02, 1.45941600416277e+02,
36 1.73302955873365e+02, 2.05794060286978e+02, 2.44376646872353e+02,
37 2.90192756065437e+02, 3.44598539797631e+02, 4.09204403447902e+02,
38 4.85922673669740e+02, 5.77024203055553e+02, 6.85205587130498e+02,
39 8.13668983291589e+02, 9.66216894324125e+02, 1.14736472207740e+03,
40 1.36247442287647e+03, 1.61791322085579e+03, 1.92124207711260e+03,
41 2.28143949334655e+03, 2.70916727454970e+03, 3.21708611729384e+03,
42 3.82023036499473e+03, 4.53645302286906e+03, 5.38695420497926e+03,
43 6.39690865534207e+03, 7.59621091765857e+03, 9.02036021061016e+03,
44 1.07115112009343e+04, 1.27197217770508e+04, 1.51044347572047e+04,
45 1.79362373905283e+04, 2.12989507320644e+04, 2.52921107370304e+04,
46 3.00339145144454e+04, 3.56647189489147e+04};
47
48 static const double kProbQDomain = 1024.0;
49 // Loudness of -15 dB (smallest expected loudness) in log domain,
50 // loudness_db = 13.5 * log10(rms);
51 static const double kLogDomainMinBinCenter = -2.57752062648587;
52 // Loudness step of 1 dB in log domain
53 static const double kLogDomainStepSizeInverse = 5.81954605750359;
54
55 static const int kTransientWidthThreshold = 7;
56 static const double kLowProbabilityThreshold = 0.2;
57
58 static const int kLowProbThresholdQ10 = static_cast<int>(
59 kLowProbabilityThreshold * kProbQDomain);
60
Histogram()61 Histogram::Histogram()
62 : num_updates_(0),
63 audio_content_q10_(0),
64 bin_count_q10_(),
65 activity_probability_(),
66 hist_bin_index_(),
67 buffer_index_(0),
68 buffer_is_full_(false),
69 len_circular_buffer_(0),
70 len_high_activity_(0) {
71 static_assert(
72 kHistSize == sizeof(kHistBinCenters) / sizeof(kHistBinCenters[0]),
73 "histogram bin centers incorrect size");
74 }
75
Histogram(int window_size)76 Histogram::Histogram(int window_size)
77 : num_updates_(0),
78 audio_content_q10_(0),
79 bin_count_q10_(),
80 activity_probability_(new int[window_size]),
81 hist_bin_index_(new int[window_size]),
82 buffer_index_(0),
83 buffer_is_full_(false),
84 len_circular_buffer_(window_size),
85 len_high_activity_(0) {}
86
~Histogram()87 Histogram::~Histogram() {}
88
Update(double rms,double activity_probaility)89 void Histogram::Update(double rms, double activity_probaility) {
90 // If circular histogram is activated then remove the oldest entry.
91 if (len_circular_buffer_ > 0)
92 RemoveOldestEntryAndUpdate();
93
94 // Find the corresponding bin.
95 int hist_index = GetBinIndex(rms);
96 // To Q10 domain.
97 int prob_q10 = static_cast<int16_t>(floor(activity_probaility *
98 kProbQDomain));
99 InsertNewestEntryAndUpdate(prob_q10, hist_index);
100 }
101
102 // Doing nothing if buffer is not full, yet.
RemoveOldestEntryAndUpdate()103 void Histogram::RemoveOldestEntryAndUpdate() {
104 assert(len_circular_buffer_ > 0);
105 // Do nothing if circular buffer is not full.
106 if (!buffer_is_full_)
107 return;
108
109 int oldest_prob = activity_probability_[buffer_index_];
110 int oldest_hist_index = hist_bin_index_[buffer_index_];
111 UpdateHist(-oldest_prob, oldest_hist_index);
112 }
113
RemoveTransient()114 void Histogram::RemoveTransient() {
115 // Don't expect to be here if high-activity region is longer than
116 // |kTransientWidthThreshold| or there has not been any transient.
117 assert(len_high_activity_ <= kTransientWidthThreshold);
118 int index = (buffer_index_ > 0) ? (buffer_index_ - 1) :
119 len_circular_buffer_ - 1;
120 while (len_high_activity_ > 0) {
121 UpdateHist(-activity_probability_[index], hist_bin_index_[index]);
122 activity_probability_[index] = 0;
123 index = (index > 0) ? (index - 1) : (len_circular_buffer_ - 1);
124 len_high_activity_--;
125 }
126 }
127
InsertNewestEntryAndUpdate(int activity_prob_q10,int hist_index)128 void Histogram::InsertNewestEntryAndUpdate(int activity_prob_q10,
129 int hist_index) {
130 // Update the circular buffer if it is enabled.
131 if (len_circular_buffer_ > 0) {
132 // Removing transient.
133 if (activity_prob_q10 <= kLowProbThresholdQ10) {
134 // Lower than threshold probability, set it to zero.
135 activity_prob_q10 = 0;
136 // Check if this has been a transient.
137 if (len_high_activity_ <= kTransientWidthThreshold)
138 RemoveTransient(); // Remove this transient.
139 len_high_activity_ = 0;
140 } else if (len_high_activity_ <= kTransientWidthThreshold) {
141 len_high_activity_++;
142 }
143 // Updating the circular buffer.
144 activity_probability_[buffer_index_] = activity_prob_q10;
145 hist_bin_index_[buffer_index_] = hist_index;
146 // Increment the buffer index and check for wrap-around.
147 buffer_index_++;
148 if (buffer_index_ >= len_circular_buffer_) {
149 buffer_index_ = 0;
150 buffer_is_full_ = true;
151 }
152 }
153
154 num_updates_++;
155 if (num_updates_ < 0)
156 num_updates_--;
157
158 UpdateHist(activity_prob_q10, hist_index);
159 }
160
UpdateHist(int activity_prob_q10,int hist_index)161 void Histogram::UpdateHist(int activity_prob_q10, int hist_index) {
162 bin_count_q10_[hist_index] += activity_prob_q10;
163 audio_content_q10_ += activity_prob_q10;
164 }
165
AudioContent() const166 double Histogram::AudioContent() const {
167 return audio_content_q10_ / kProbQDomain;
168 }
169
Create()170 Histogram* Histogram::Create() {
171 return new Histogram;
172 }
173
Create(int window_size)174 Histogram* Histogram::Create(int window_size) {
175 if (window_size < 0)
176 return NULL;
177 return new Histogram(window_size);
178 }
179
Reset()180 void Histogram::Reset() {
181 // Reset the histogram, audio-content and number of updates.
182 memset(bin_count_q10_, 0, sizeof(bin_count_q10_));
183 audio_content_q10_ = 0;
184 num_updates_ = 0;
185 // Empty the circular buffer.
186 buffer_index_ = 0;
187 buffer_is_full_ = false;
188 len_high_activity_ = 0;
189 }
190
GetBinIndex(double rms)191 int Histogram::GetBinIndex(double rms) {
192 // First exclude overload cases.
193 if (rms <= kHistBinCenters[0]) {
194 return 0;
195 } else if (rms >= kHistBinCenters[kHistSize - 1]) {
196 return kHistSize - 1;
197 } else {
198 // The quantizer is uniform in log domain. Alternatively we could do binary
199 // search in linear domain.
200 double rms_log = log(rms);
201
202 int index = static_cast<int>(floor((rms_log - kLogDomainMinBinCenter) *
203 kLogDomainStepSizeInverse));
204 // The final decision is in linear domain.
205 double b = 0.5 * (kHistBinCenters[index] + kHistBinCenters[index + 1]);
206 if (rms > b) {
207 return index + 1;
208 }
209 return index;
210 }
211 }
212
CurrentRms() const213 double Histogram::CurrentRms() const {
214 double p;
215 double mean_val = 0;
216 if (audio_content_q10_ > 0) {
217 double p_total_inverse = 1. / static_cast<double>(audio_content_q10_);
218 for (int n = 0; n < kHistSize; n++) {
219 p = static_cast<double>(bin_count_q10_[n]) * p_total_inverse;
220 mean_val += p * kHistBinCenters[n];
221 }
222 } else {
223 mean_val = kHistBinCenters[0];
224 }
225 return mean_val;
226 }
227
228 } // namespace webrtc
229