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* Copyright (c) 2017 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 <math.h>
#include <stddef.h>
#include <array>
#include <vector>
#include "api/array_view.h"
#include "api/audio/echo_canceller3_config.h"
#include "modules/audio_processing/aec3/adaptive_fir_filter.h"
#include "modules/audio_processing/aec3/aec3_common.h"
#include "modules/audio_processing/aec3/aec3_fft.h"
#include "modules/audio_processing/aec3/aec_state.h"
#include "modules/audio_processing/aec3/echo_path_variability.h"
#include "modules/audio_processing/aec3/main_filter_update_gain.h"
#include "modules/audio_processing/aec3/render_buffer.h"
#include "modules/audio_processing/aec3/render_signal_analyzer.h"
#include "modules/audio_processing/aec3/shadow_filter_update_gain.h"
#include "modules/audio_processing/aec3/subtractor_output.h"
#include "modules/audio_processing/logging/apm_data_dumper.h"
#include "rtc_base/checks.h"
#include "rtc_base/constructormagic.h"
namespace webrtc {
// Proves linear echo cancellation functionality
class Subtractor {
Subtractor(const EchoCanceller3Config& config,
ApmDataDumper* data_dumper,
Aec3Optimization optimization);
// Performs the echo subtraction.
void Process(const RenderBuffer& render_buffer,
const rtc::ArrayView<const float> capture,
const RenderSignalAnalyzer& render_signal_analyzer,
const AecState& aec_state,
SubtractorOutput* output);
void HandleEchoPathChange(const EchoPathVariability& echo_path_variability);
// Exits the initial state.
void ExitInitialState();
// Returns the block-wise frequency response for the main adaptive filter.
const std::vector<std::array<float, kFftLengthBy2Plus1>>&
FilterFrequencyResponse() const {
return main_filter_.FilterFrequencyResponse();
// Returns the estimate of the impulse response for the main adaptive filter.
const std::vector<float>& FilterImpulseResponse() const {
return main_filter_.FilterImpulseResponse();
void DumpFilters() {
main_filter_.DumpFilter("aec3_subtractor_H_main", "aec3_subtractor_h_main");
class FilterMisadjustmentEstimator {
FilterMisadjustmentEstimator() = default;
~FilterMisadjustmentEstimator() = default;
// Update the misadjustment estimator.
void Update(const SubtractorOutput& output);
// GetMisadjustment() Returns a recommended scale for the filter so the
// prediction error energy gets closer to the energy that is seen at the
// microphone input.
float GetMisadjustment() const {
RTC_DCHECK_GT(inv_misadjustment_, 0.0f);
// It is not aiming to adjust all the estimated mismatch. Instead,
// it adjusts half of that estimated mismatch.
return 2.f / sqrtf(inv_misadjustment_);
// Returns true if the prediciton error energy is significantly larger
// than the microphone signal energy and, therefore, an adjustment is
// recommended.
bool IsAdjustmentNeeded() const { return inv_misadjustment_ > 10.f; }
void Reset();
void Dump(ApmDataDumper* data_dumper) const;
const int n_blocks_ = 4;
int n_blocks_acum_ = 0;
float e2_acum_ = 0.f;
float y2_acum_ = 0.f;
float inv_misadjustment_ = 0.f;
int overhang_ = 0.f;
const Aec3Fft fft_;
ApmDataDumper* data_dumper_;
const Aec3Optimization optimization_;
const EchoCanceller3Config config_;
const bool adaptation_during_saturation_;
const bool enable_misadjustment_estimator_;
const bool enable_agc_gain_change_response_;
const bool enable_shadow_filter_jumpstart_;
const bool enable_shadow_filter_boosted_jumpstart_;
const bool enable_early_shadow_filter_jumpstart_;
AdaptiveFirFilter main_filter_;
AdaptiveFirFilter shadow_filter_;
MainFilterUpdateGain G_main_;
ShadowFilterUpdateGain G_shadow_;
FilterMisadjustmentEstimator filter_misadjustment_estimator_;
size_t poor_shadow_filter_counter_ = 0;
} // namespace webrtc