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