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Diffstat (limited to 'third_party/libwebrtc/modules/audio_processing/agc/loudness_histogram.cc')
-rw-r--r-- | third_party/libwebrtc/modules/audio_processing/agc/loudness_histogram.cc | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/third_party/libwebrtc/modules/audio_processing/agc/loudness_histogram.cc b/third_party/libwebrtc/modules/audio_processing/agc/loudness_histogram.cc new file mode 100644 index 0000000000..b0a1f53b97 --- /dev/null +++ b/third_party/libwebrtc/modules/audio_processing/agc/loudness_histogram.cc @@ -0,0 +1,229 @@ +/* + * 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 |