230 lines
8.0 KiB
C++
230 lines
8.0 KiB
C++
/*
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* Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "modules/audio_processing/agc/loudness_histogram.h"
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#include <string.h>
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#include <cmath>
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#include "rtc_base/checks.h"
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namespace webrtc {
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static const double kHistBinCenters[] = {
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7.59621091765857e-02, 9.02036021061016e-02, 1.07115112009343e-01,
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1.27197217770508e-01, 1.51044347572047e-01, 1.79362373905283e-01,
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2.12989507320644e-01, 2.52921107370304e-01, 3.00339145144454e-01,
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3.56647189489147e-01, 4.23511952494003e-01, 5.02912623991786e-01,
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5.97199455365749e-01, 7.09163326739184e-01, 8.42118356728544e-01,
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1.00000000000000e+00, 1.18748153630660e+00, 1.41011239906908e+00,
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1.67448243801153e+00, 1.98841697800836e+00, 2.36120844786349e+00,
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2.80389143520905e+00, 3.32956930911896e+00, 3.95380207843188e+00,
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4.69506696634852e+00, 5.57530533426190e+00, 6.62057214370769e+00,
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7.86180718043869e+00, 9.33575086877358e+00, 1.10860317842269e+01,
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1.31644580546776e+01, 1.56325508754123e+01, 1.85633655299256e+01,
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2.20436538184971e+01, 2.61764319021997e+01, 3.10840295702492e+01,
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3.69117111886792e+01, 4.38319755100383e+01, 5.20496616180135e+01,
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6.18080121423973e+01, 7.33958732149108e+01, 8.71562442838066e+01,
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1.03496430860848e+02, 1.22900100720889e+02, 1.45941600416277e+02,
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1.73302955873365e+02, 2.05794060286978e+02, 2.44376646872353e+02,
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2.90192756065437e+02, 3.44598539797631e+02, 4.09204403447902e+02,
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4.85922673669740e+02, 5.77024203055553e+02, 6.85205587130498e+02,
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8.13668983291589e+02, 9.66216894324125e+02, 1.14736472207740e+03,
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1.36247442287647e+03, 1.61791322085579e+03, 1.92124207711260e+03,
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2.28143949334655e+03, 2.70916727454970e+03, 3.21708611729384e+03,
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3.82023036499473e+03, 4.53645302286906e+03, 5.38695420497926e+03,
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6.39690865534207e+03, 7.59621091765857e+03, 9.02036021061016e+03,
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1.07115112009343e+04, 1.27197217770508e+04, 1.51044347572047e+04,
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1.79362373905283e+04, 2.12989507320644e+04, 2.52921107370304e+04,
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3.00339145144454e+04, 3.56647189489147e+04};
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static const double kProbQDomain = 1024.0;
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// Loudness of -15 dB (smallest expected loudness) in log domain,
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// loudness_db = 13.5 * log10(rms);
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static const double kLogDomainMinBinCenter = -2.57752062648587;
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// Loudness step of 1 dB in log domain
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static const double kLogDomainStepSizeInverse = 5.81954605750359;
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static const int kTransientWidthThreshold = 7;
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static const double kLowProbabilityThreshold = 0.2;
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static const int kLowProbThresholdQ10 =
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static_cast<int>(kLowProbabilityThreshold * kProbQDomain);
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LoudnessHistogram::LoudnessHistogram()
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: num_updates_(0),
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audio_content_q10_(0),
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bin_count_q10_(),
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activity_probability_(),
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hist_bin_index_(),
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buffer_index_(0),
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buffer_is_full_(false),
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len_circular_buffer_(0),
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len_high_activity_(0) {
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static_assert(
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kHistSize == sizeof(kHistBinCenters) / sizeof(kHistBinCenters[0]),
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"histogram bin centers incorrect size");
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}
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LoudnessHistogram::LoudnessHistogram(int window_size)
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: num_updates_(0),
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audio_content_q10_(0),
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bin_count_q10_(),
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activity_probability_(new int[window_size]),
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hist_bin_index_(new int[window_size]),
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buffer_index_(0),
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buffer_is_full_(false),
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len_circular_buffer_(window_size),
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len_high_activity_(0) {}
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LoudnessHistogram::~LoudnessHistogram() {}
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void LoudnessHistogram::Update(double rms, double activity_probaility) {
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// If circular histogram is activated then remove the oldest entry.
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if (len_circular_buffer_ > 0)
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RemoveOldestEntryAndUpdate();
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// Find the corresponding bin.
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int hist_index = GetBinIndex(rms);
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// To Q10 domain.
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int prob_q10 =
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static_cast<int16_t>(floor(activity_probaility * kProbQDomain));
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InsertNewestEntryAndUpdate(prob_q10, hist_index);
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}
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// Doing nothing if buffer is not full, yet.
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void LoudnessHistogram::RemoveOldestEntryAndUpdate() {
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RTC_DCHECK_GT(len_circular_buffer_, 0);
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// Do nothing if circular buffer is not full.
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if (!buffer_is_full_)
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return;
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int oldest_prob = activity_probability_[buffer_index_];
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int oldest_hist_index = hist_bin_index_[buffer_index_];
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UpdateHist(-oldest_prob, oldest_hist_index);
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}
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void LoudnessHistogram::RemoveTransient() {
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// Don't expect to be here if high-activity region is longer than
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// |kTransientWidthThreshold| or there has not been any transient.
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RTC_DCHECK_LE(len_high_activity_, kTransientWidthThreshold);
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int index =
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(buffer_index_ > 0) ? (buffer_index_ - 1) : len_circular_buffer_ - 1;
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while (len_high_activity_ > 0) {
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UpdateHist(-activity_probability_[index], hist_bin_index_[index]);
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activity_probability_[index] = 0;
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index = (index > 0) ? (index - 1) : (len_circular_buffer_ - 1);
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len_high_activity_--;
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}
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}
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void LoudnessHistogram::InsertNewestEntryAndUpdate(int activity_prob_q10,
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int hist_index) {
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// Update the circular buffer if it is enabled.
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if (len_circular_buffer_ > 0) {
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// Removing transient.
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if (activity_prob_q10 <= kLowProbThresholdQ10) {
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// Lower than threshold probability, set it to zero.
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activity_prob_q10 = 0;
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// Check if this has been a transient.
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if (len_high_activity_ <= kTransientWidthThreshold)
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RemoveTransient(); // Remove this transient.
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len_high_activity_ = 0;
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} else if (len_high_activity_ <= kTransientWidthThreshold) {
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len_high_activity_++;
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}
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// Updating the circular buffer.
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activity_probability_[buffer_index_] = activity_prob_q10;
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hist_bin_index_[buffer_index_] = hist_index;
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// Increment the buffer index and check for wrap-around.
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buffer_index_++;
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if (buffer_index_ >= len_circular_buffer_) {
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buffer_index_ = 0;
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buffer_is_full_ = true;
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}
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}
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num_updates_++;
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if (num_updates_ < 0)
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num_updates_--;
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UpdateHist(activity_prob_q10, hist_index);
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}
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void LoudnessHistogram::UpdateHist(int activity_prob_q10, int hist_index) {
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bin_count_q10_[hist_index] += activity_prob_q10;
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audio_content_q10_ += activity_prob_q10;
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}
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double LoudnessHistogram::AudioContent() const {
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return audio_content_q10_ / kProbQDomain;
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}
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LoudnessHistogram* LoudnessHistogram::Create() {
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return new LoudnessHistogram;
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}
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LoudnessHistogram* LoudnessHistogram::Create(int window_size) {
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if (window_size < 0)
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return NULL;
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return new LoudnessHistogram(window_size);
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}
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void LoudnessHistogram::Reset() {
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// Reset the histogram, audio-content and number of updates.
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memset(bin_count_q10_, 0, sizeof(bin_count_q10_));
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audio_content_q10_ = 0;
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num_updates_ = 0;
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// Empty the circular buffer.
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buffer_index_ = 0;
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buffer_is_full_ = false;
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len_high_activity_ = 0;
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}
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int LoudnessHistogram::GetBinIndex(double rms) {
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// First exclude overload cases.
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if (rms <= kHistBinCenters[0]) {
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return 0;
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} else if (rms >= kHistBinCenters[kHistSize - 1]) {
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return kHistSize - 1;
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} else {
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// The quantizer is uniform in log domain. Alternatively we could do binary
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// search in linear domain.
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double rms_log = log(rms);
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int index = static_cast<int>(
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floor((rms_log - kLogDomainMinBinCenter) * kLogDomainStepSizeInverse));
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// The final decision is in linear domain.
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double b = 0.5 * (kHistBinCenters[index] + kHistBinCenters[index + 1]);
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if (rms > b) {
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return index + 1;
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}
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return index;
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}
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}
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double LoudnessHistogram::CurrentRms() const {
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double p;
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double mean_val = 0;
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if (audio_content_q10_ > 0) {
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double p_total_inverse = 1. / static_cast<double>(audio_content_q10_);
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for (int n = 0; n < kHistSize; n++) {
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p = static_cast<double>(bin_count_q10_[n]) * p_total_inverse;
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mean_val += p * kHistBinCenters[n];
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}
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} else {
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mean_val = kHistBinCenters[0];
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}
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return mean_val;
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}
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} // namespace webrtc
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