| /* |
| * Copyright (c) 2018 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. |
| */ |
| |
| #ifndef MODULES_AUDIO_PROCESSING_AEC3_STATIONARITY_ESTIMATOR_H_ |
| #define MODULES_AUDIO_PROCESSING_AEC3_STATIONARITY_ESTIMATOR_H_ |
| |
| #include <stddef.h> |
| |
| #include <array> |
| #include <memory> |
| |
| #include "api/array_view.h" |
| #include "modules/audio_processing/aec3/aec3_common.h" // kFftLengthBy2Plus1... |
| #include "modules/audio_processing/aec3/reverb_model.h" |
| #include "rtc_base/checks.h" |
| |
| namespace webrtc { |
| |
| class ApmDataDumper; |
| struct VectorBuffer; |
| |
| class StationarityEstimator { |
| public: |
| StationarityEstimator(); |
| ~StationarityEstimator(); |
| |
| // Reset the stationarity estimator. |
| void Reset(); |
| |
| // Update just the noise estimator. Usefull until the delay is known |
| void UpdateNoiseEstimator(rtc::ArrayView<const float> spectrum); |
| |
| // Update the flag indicating whether this current frame is stationary. For |
| // getting a more robust estimation, it looks at future and/or past frames. |
| void UpdateStationarityFlags( |
| const VectorBuffer& spectrum_buffer, |
| rtc::ArrayView<const float> render_reverb_contribution_spectrum, |
| int idx_current, |
| int num_lookahead); |
| |
| // Returns true if the current band is stationary. |
| bool IsBandStationary(size_t band) const { |
| return stationarity_flags_[band] && (hangovers_[band] == 0); |
| } |
| |
| // Returns true if the current block is estimated as stationary. |
| bool IsBlockStationary() const; |
| |
| private: |
| static constexpr int kWindowLength = 13; |
| // Returns the power of the stationary noise spectrum at a band. |
| float GetStationarityPowerBand(size_t k) const { return noise_.Power(k); } |
| |
| // Get an estimation of the stationarity for the current band by looking |
| // at the past/present/future available data. |
| bool EstimateBandStationarity(const VectorBuffer& spectrum_buffer, |
| rtc::ArrayView<const float> reverb, |
| const std::array<int, kWindowLength>& indexes, |
| size_t band) const; |
| |
| // True if all bands at the current point are stationary. |
| bool AreAllBandsStationary(); |
| |
| // Update the hangover depending on the stationary status of the current |
| // frame. |
| void UpdateHangover(); |
| |
| // Smooth the stationarity detection by looking at neighbouring frequency |
| // bands. |
| void SmoothStationaryPerFreq(); |
| |
| class NoiseSpectrum { |
| public: |
| NoiseSpectrum(); |
| ~NoiseSpectrum(); |
| |
| // Reset the noise power spectrum estimate state. |
| void Reset(); |
| |
| // Update the noise power spectrum with a new frame. |
| void Update(rtc::ArrayView<const float> spectrum); |
| |
| // Get the noise estimation power spectrum. |
| rtc::ArrayView<const float> Spectrum() const { return noise_spectrum_; } |
| |
| // Get the noise power spectrum at a certain band. |
| float Power(size_t band) const { |
| RTC_DCHECK_LT(band, noise_spectrum_.size()); |
| return noise_spectrum_[band]; |
| } |
| |
| private: |
| // Get the update coefficient to be used for the current frame. |
| float GetAlpha() const; |
| |
| // Update the noise power spectrum at a certain band with a new frame. |
| float UpdateBandBySmoothing(float power_band, |
| float power_band_noise, |
| float alpha) const; |
| std::array<float, kFftLengthBy2Plus1> noise_spectrum_; |
| size_t block_counter_; |
| }; |
| |
| static int instance_count_; |
| std::unique_ptr<ApmDataDumper> data_dumper_; |
| NoiseSpectrum noise_; |
| std::array<int, kFftLengthBy2Plus1> hangovers_; |
| std::array<bool, kFftLengthBy2Plus1> stationarity_flags_; |
| }; |
| |
| } // namespace webrtc |
| |
| #endif // MODULES_AUDIO_PROCESSING_AEC3_STATIONARITY_ESTIMATOR_H_ |