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Diffstat (limited to 'webrtc/modules/audio_processing/ns/noise_estimator.cc')
| -rw-r--r-- | webrtc/modules/audio_processing/ns/noise_estimator.cc | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/webrtc/modules/audio_processing/ns/noise_estimator.cc b/webrtc/modules/audio_processing/ns/noise_estimator.cc new file mode 100644 index 0000000..5367545 --- /dev/null +++ b/webrtc/modules/audio_processing/ns/noise_estimator.cc @@ -0,0 +1,195 @@ +/* + * Copyright (c) 2019 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/ns/noise_estimator.h" + +#include <algorithm> + +#include "modules/audio_processing/ns/fast_math.h" +#include "rtc_base/checks.h" + +namespace webrtc { + +namespace { + +// Log(i). +constexpr std::array<float, 129> log_table = { + 0.f, 0.f, 0.f, 0.f, 0.f, 1.609438f, 1.791759f, + 1.945910f, 2.079442f, 2.197225f, 2.302585f, 2.397895f, 2.484907f, 2.564949f, + 2.639057f, 2.708050f, 2.772589f, 2.833213f, 2.890372f, 2.944439f, 2.995732f, + 3.044522f, 3.091043f, 3.135494f, 3.178054f, 3.218876f, 3.258097f, 3.295837f, + 3.332205f, 3.367296f, 3.401197f, 3.433987f, 3.465736f, 3.496507f, 3.526361f, + 3.555348f, 3.583519f, 3.610918f, 3.637586f, 3.663562f, 3.688879f, 3.713572f, + 3.737669f, 3.761200f, 3.784190f, 3.806663f, 3.828641f, 3.850147f, 3.871201f, + 3.891820f, 3.912023f, 3.931826f, 3.951244f, 3.970292f, 3.988984f, 4.007333f, + 4.025352f, 4.043051f, 4.060443f, 4.077538f, 4.094345f, 4.110874f, 4.127134f, + 4.143135f, 4.158883f, 4.174387f, 4.189655f, 4.204693f, 4.219508f, 4.234107f, + 4.248495f, 4.262680f, 4.276666f, 4.290460f, 4.304065f, 4.317488f, 4.330733f, + 4.343805f, 4.356709f, 4.369448f, 4.382027f, 4.394449f, 4.406719f, 4.418841f, + 4.430817f, 4.442651f, 4.454347f, 4.465908f, 4.477337f, 4.488636f, 4.499810f, + 4.510859f, 4.521789f, 4.532599f, 4.543295f, 4.553877f, 4.564348f, 4.574711f, + 4.584968f, 4.595119f, 4.605170f, 4.615121f, 4.624973f, 4.634729f, 4.644391f, + 4.653960f, 4.663439f, 4.672829f, 4.682131f, 4.691348f, 4.700480f, 4.709530f, + 4.718499f, 4.727388f, 4.736198f, 4.744932f, 4.753591f, 4.762174f, 4.770685f, + 4.779124f, 4.787492f, 4.795791f, 4.804021f, 4.812184f, 4.820282f, 4.828314f, + 4.836282f, 4.844187f, 4.852030f}; + +} // namespace + +NoiseEstimator::NoiseEstimator(const SuppressionParams& suppression_params) + : suppression_params_(suppression_params) { + noise_spectrum_.fill(0.f); + prev_noise_spectrum_.fill(0.f); + conservative_noise_spectrum_.fill(0.f); + parametric_noise_spectrum_.fill(0.f); +} + +void NoiseEstimator::PrepareAnalysis() { + std::copy(noise_spectrum_.begin(), noise_spectrum_.end(), + prev_noise_spectrum_.begin()); +} + +void NoiseEstimator::PreUpdate( + int32_t num_analyzed_frames, + rtc::ArrayView<const float, kFftSizeBy2Plus1> signal_spectrum, + float signal_spectral_sum) { + quantile_noise_estimator_.Estimate(signal_spectrum, noise_spectrum_); + + if (num_analyzed_frames < kShortStartupPhaseBlocks) { + // Compute simplified noise model during startup. + const size_t kStartBand = 5; + float sum_log_i_log_magn = 0.f; + float sum_log_i = 0.f; + float sum_log_i_square = 0.f; + float sum_log_magn = 0.f; + for (size_t i = kStartBand; i < kFftSizeBy2Plus1; ++i) { + float log_i = log_table[i]; + sum_log_i += log_i; + sum_log_i_square += log_i * log_i; + float log_signal = LogApproximation(signal_spectrum[i]); + sum_log_magn += log_signal; + sum_log_i_log_magn += log_i * log_signal; + } + + // Estimate the parameter for the level of the white noise. + constexpr float kOneByFftSizeBy2Plus1 = 1.f / kFftSizeBy2Plus1; + white_noise_level_ += signal_spectral_sum * kOneByFftSizeBy2Plus1 * + suppression_params_.over_subtraction_factor; + + // Estimate pink noise parameters. + float denom = sum_log_i_square * (kFftSizeBy2Plus1 - kStartBand) - + sum_log_i * sum_log_i; + float num = + sum_log_i_square * sum_log_magn - sum_log_i * sum_log_i_log_magn; + RTC_DCHECK_NE(denom, 0.f); + float pink_noise_adjustment = num / denom; + + // Constrain the estimated spectrum to be positive. + pink_noise_adjustment = std::max(pink_noise_adjustment, 0.f); + pink_noise_numerator_ += pink_noise_adjustment; + num = sum_log_i * sum_log_magn - + (kFftSizeBy2Plus1 - kStartBand) * sum_log_i_log_magn; + RTC_DCHECK_NE(denom, 0.f); + pink_noise_adjustment = num / denom; + + // Constrain the pink noise power to be in the interval [0, 1]. + pink_noise_adjustment = std::max(std::min(pink_noise_adjustment, 1.f), 0.f); + + pink_noise_exp_ += pink_noise_adjustment; + + const float one_by_num_analyzed_frames_plus_1 = + 1.f / (num_analyzed_frames + 1.f); + + // Calculate the frequency-independent parts of parametric noise estimate. + float parametric_exp = 0.f; + float parametric_num = 0.f; + if (pink_noise_exp_ > 0.f) { + // Use pink noise estimate. + parametric_num = ExpApproximation(pink_noise_numerator_ * + one_by_num_analyzed_frames_plus_1); + parametric_num *= num_analyzed_frames + 1.f; + parametric_exp = pink_noise_exp_ * one_by_num_analyzed_frames_plus_1; + } + + constexpr float kOneByShortStartupPhaseBlocks = + 1.f / kShortStartupPhaseBlocks; + for (size_t i = 0; i < kFftSizeBy2Plus1; ++i) { + // Estimate the background noise using the white and pink noise + // parameters. + if (pink_noise_exp_ == 0.f) { + // Use white noise estimate. + parametric_noise_spectrum_[i] = white_noise_level_; + } else { + // Use pink noise estimate. + float use_band = i < kStartBand ? kStartBand : i; + float denom = PowApproximation(use_band, parametric_exp); + RTC_DCHECK_NE(denom, 0.f); + parametric_noise_spectrum_[i] = parametric_num / denom; + } + } + + // Weight quantile noise with modeled noise. + for (size_t i = 0; i < kFftSizeBy2Plus1; ++i) { + noise_spectrum_[i] *= num_analyzed_frames; + float tmp = parametric_noise_spectrum_[i] * + (kShortStartupPhaseBlocks - num_analyzed_frames); + noise_spectrum_[i] += tmp * one_by_num_analyzed_frames_plus_1; + noise_spectrum_[i] *= kOneByShortStartupPhaseBlocks; + } + } +} + +void NoiseEstimator::PostUpdate( + rtc::ArrayView<const float> speech_probability, + rtc::ArrayView<const float, kFftSizeBy2Plus1> signal_spectrum) { + // Time-avg parameter for noise_spectrum update. + constexpr float kNoiseUpdate = 0.9f; + + float gamma = kNoiseUpdate; + for (size_t i = 0; i < kFftSizeBy2Plus1; ++i) { + const float prob_speech = speech_probability[i]; + const float prob_non_speech = 1.f - prob_speech; + + // Temporary noise update used for speech frames if update value is less + // than previous. + float noise_update_tmp = + gamma * prev_noise_spectrum_[i] + + (1.f - gamma) * (prob_non_speech * signal_spectrum[i] + + prob_speech * prev_noise_spectrum_[i]); + + // Time-constant based on speech/noise_spectrum state. + float gamma_old = gamma; + + // Increase gamma for frame likely to be seech. + constexpr float kProbRange = .2f; + gamma = prob_speech > kProbRange ? .99f : kNoiseUpdate; + + // Conservative noise_spectrum update. + if (prob_speech < kProbRange) { + conservative_noise_spectrum_[i] += + 0.05f * (signal_spectrum[i] - conservative_noise_spectrum_[i]); + } + + // Noise_spectrum update. + if (gamma == gamma_old) { + noise_spectrum_[i] = noise_update_tmp; + } else { + noise_spectrum_[i] = + gamma * prev_noise_spectrum_[i] + + (1.f - gamma) * (prob_non_speech * signal_spectrum[i] + + prob_speech * prev_noise_spectrum_[i]); + // Allow for noise_spectrum update downwards: If noise_spectrum update + // decreases the noise_spectrum, it is safe, so allow it to happen. + noise_spectrum_[i] = std::min(noise_spectrum_[i], noise_update_tmp); + } + } +} + +} // namespace webrtc |