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Diffstat (limited to 'webrtc/modules/audio_processing/agc/pitch_based_vad.cc')
-rw-r--r-- | webrtc/modules/audio_processing/agc/pitch_based_vad.cc | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/webrtc/modules/audio_processing/agc/pitch_based_vad.cc b/webrtc/modules/audio_processing/agc/pitch_based_vad.cc new file mode 100644 index 0000000000..0cfa52a010 --- /dev/null +++ b/webrtc/modules/audio_processing/agc/pitch_based_vad.cc @@ -0,0 +1,122 @@ +/* + * 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 "webrtc/modules/audio_processing/agc/pitch_based_vad.h" + +#include <assert.h> +#include <math.h> +#include <string.h> + +#include "webrtc/modules/audio_processing/agc/circular_buffer.h" +#include "webrtc/modules/audio_processing/agc/common.h" +#include "webrtc/modules/audio_processing/agc/noise_gmm_tables.h" +#include "webrtc/modules/audio_processing/agc/voice_gmm_tables.h" +#include "webrtc/modules/interface/module_common_types.h" + +namespace webrtc { + +static_assert(kNoiseGmmDim == kVoiceGmmDim, + "noise and voice gmm dimension not equal"); + +// These values should match MATLAB counterparts for unit-tests to pass. +static const int kPosteriorHistorySize = 500; // 5 sec of 10 ms frames. +static const double kInitialPriorProbability = 0.3; +static const int kTransientWidthThreshold = 7; +static const double kLowProbabilityThreshold = 0.2; + +static double LimitProbability(double p) { + const double kLimHigh = 0.99; + const double kLimLow = 0.01; + + if (p > kLimHigh) + p = kLimHigh; + else if (p < kLimLow) + p = kLimLow; + return p; +} + +PitchBasedVad::PitchBasedVad() + : p_prior_(kInitialPriorProbability), + circular_buffer_(AgcCircularBuffer::Create(kPosteriorHistorySize)) { + // Setup noise GMM. + noise_gmm_.dimension = kNoiseGmmDim; + noise_gmm_.num_mixtures = kNoiseGmmNumMixtures; + noise_gmm_.weight = kNoiseGmmWeights; + noise_gmm_.mean = &kNoiseGmmMean[0][0]; + noise_gmm_.covar_inverse = &kNoiseGmmCovarInverse[0][0][0]; + + // Setup voice GMM. + voice_gmm_.dimension = kVoiceGmmDim; + voice_gmm_.num_mixtures = kVoiceGmmNumMixtures; + voice_gmm_.weight = kVoiceGmmWeights; + voice_gmm_.mean = &kVoiceGmmMean[0][0]; + voice_gmm_.covar_inverse = &kVoiceGmmCovarInverse[0][0][0]; +} + +PitchBasedVad::~PitchBasedVad() {} + +int PitchBasedVad::VoicingProbability(const AudioFeatures& features, + double* p_combined) { + double p; + double gmm_features[3]; + double pdf_features_given_voice; + double pdf_features_given_noise; + // These limits are the same in matlab implementation 'VoicingProbGMM().' + const double kLimLowLogPitchGain = -2.0; + const double kLimHighLogPitchGain = -0.9; + const double kLimLowSpectralPeak = 200; + const double kLimHighSpectralPeak = 2000; + const double kEps = 1e-12; + for (int n = 0; n < features.num_frames; n++) { + gmm_features[0] = features.log_pitch_gain[n]; + gmm_features[1] = features.spectral_peak[n]; + gmm_features[2] = features.pitch_lag_hz[n]; + + pdf_features_given_voice = EvaluateGmm(gmm_features, voice_gmm_); + pdf_features_given_noise = EvaluateGmm(gmm_features, noise_gmm_); + + if (features.spectral_peak[n] < kLimLowSpectralPeak || + features.spectral_peak[n] > kLimHighSpectralPeak || + features.log_pitch_gain[n] < kLimLowLogPitchGain) { + pdf_features_given_voice = kEps * pdf_features_given_noise; + } else if (features.log_pitch_gain[n] > kLimHighLogPitchGain) { + pdf_features_given_noise = kEps * pdf_features_given_voice; + } + + p = p_prior_ * pdf_features_given_voice / (pdf_features_given_voice * + p_prior_ + pdf_features_given_noise * (1 - p_prior_)); + + p = LimitProbability(p); + + // Combine pitch-based probability with standalone probability, before + // updating prior probabilities. + double prod_active = p * p_combined[n]; + double prod_inactive = (1 - p) * (1 - p_combined[n]); + p_combined[n] = prod_active / (prod_active + prod_inactive); + + if (UpdatePrior(p_combined[n]) < 0) + return -1; + // Limit prior probability. With a zero prior probability the posterior + // probability is always zero. + p_prior_ = LimitProbability(p_prior_); + } + return 0; +} + +int PitchBasedVad::UpdatePrior(double p) { + circular_buffer_->Insert(p); + if (circular_buffer_->RemoveTransient(kTransientWidthThreshold, + kLowProbabilityThreshold) < 0) + return -1; + p_prior_ = circular_buffer_->Mean(); + return 0; +} + +} // namespace webrtc |