075cb2b2f7
In this work we introduce some changes on how the reverberation model for AEC3 is applied. Currently, the exponential modelling of the tails is applied over the linear echo estimates. That might result in an overestimation of the reverberation tails under certain conditions. In this work, the reverberation model is instead applied over an estimate of the energies at the tails of the linear estimate. Additionally, the stationary estimator is changed so it does not disable the aec immediately after a burst of activity. Bug: webrtc:9384,webrtc:9400,chromium:852257 Change-Id: Ia486694ed326cfe231fc688877c0b9b6e2c450ff Reviewed-on: https://webrtc-review.googlesource.com/82161 Reviewed-by: Per Åhgren <peah@webrtc.org> Commit-Queue: Jesus de Vicente Pena <devicentepena@webrtc.org> Cr-Commit-Position: refs/heads/master@{#23599}
305 lines
11 KiB
C++
305 lines
11 KiB
C++
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/*
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* Copyright (c) 2017 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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#include "modules/audio_processing/aec3/residual_echo_estimator.h"
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#include <numeric>
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#include <vector>
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#include "modules/audio_processing/aec3/reverb_model.h"
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#include "modules/audio_processing/aec3/reverb_model_fallback.h"
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#include "rtc_base/checks.h"
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#include "system_wrappers/include/field_trial.h"
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namespace webrtc {
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namespace {
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bool EnableSoftTransparentMode() {
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return !field_trial::IsEnabled("WebRTC-Aec3SoftTransparentModeKillSwitch");
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}
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bool OverrideEstimatedEchoPathGain() {
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return !field_trial::IsEnabled("WebRTC-Aec3OverrideEchoPathGainKillSwitch");
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}
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// Computes the indexes that will be used for computing spectral power over
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// the blocks surrounding the delay.
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void GetRenderIndexesToAnalyze(
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const VectorBuffer& spectrum_buffer,
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const EchoCanceller3Config::EchoModel& echo_model,
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int filter_delay_blocks,
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bool gain_limiter_running,
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int headroom,
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int* idx_start,
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int* idx_stop) {
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RTC_DCHECK(idx_start);
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RTC_DCHECK(idx_stop);
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if (gain_limiter_running) {
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if (static_cast<size_t>(headroom) >
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echo_model.render_post_window_size_init) {
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*idx_start = spectrum_buffer.OffsetIndex(
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spectrum_buffer.read,
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-static_cast<int>(echo_model.render_post_window_size_init));
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} else {
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*idx_start = spectrum_buffer.IncIndex(spectrum_buffer.write);
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}
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*idx_stop = spectrum_buffer.OffsetIndex(
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spectrum_buffer.read, echo_model.render_pre_window_size_init);
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} else {
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size_t window_start;
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size_t window_end;
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window_start =
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std::max(0, filter_delay_blocks -
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static_cast<int>(echo_model.render_pre_window_size));
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window_end = filter_delay_blocks +
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static_cast<int>(echo_model.render_post_window_size);
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*idx_start =
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spectrum_buffer.OffsetIndex(spectrum_buffer.read, window_start);
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*idx_stop =
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spectrum_buffer.OffsetIndex(spectrum_buffer.read, window_end + 1);
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}
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}
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} // namespace
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ResidualEchoEstimator::ResidualEchoEstimator(const EchoCanceller3Config& config)
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: config_(config),
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soft_transparent_mode_(EnableSoftTransparentMode()),
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override_estimated_echo_path_gain_(OverrideEstimatedEchoPathGain()) {
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if (config_.ep_strength.reverb_based_on_render) {
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echo_reverb_.reset(new ReverbModel());
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} else {
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echo_reverb_fallback.reset(
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new ReverbModelFallback(config_.filter.main.length_blocks));
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}
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Reset();
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}
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ResidualEchoEstimator::~ResidualEchoEstimator() = default;
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void ResidualEchoEstimator::Estimate(
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const AecState& aec_state,
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const RenderBuffer& render_buffer,
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const std::array<float, kFftLengthBy2Plus1>& S2_linear,
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const std::array<float, kFftLengthBy2Plus1>& Y2,
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std::array<float, kFftLengthBy2Plus1>* R2) {
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RTC_DCHECK(R2);
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// Estimate the power of the stationary noise in the render signal.
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RenderNoisePower(render_buffer, &X2_noise_floor_, &X2_noise_floor_counter_);
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// Estimate the residual echo power.
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if (aec_state.UsableLinearEstimate()) {
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RTC_DCHECK(!aec_state.SaturatedEcho());
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LinearEstimate(S2_linear, aec_state.Erle(), R2);
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// Adds the estimated unmodelled echo power to the residual echo power
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// estimate.
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if (echo_reverb_) {
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echo_reverb_->AddReverb(
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render_buffer.Spectrum(aec_state.FilterLengthBlocks() + 1),
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aec_state.GetFilterTailGain(), aec_state.ReverbDecay(), *R2);
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} else {
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RTC_DCHECK(echo_reverb_fallback);
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echo_reverb_fallback->AddEchoReverb(S2_linear,
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aec_state.FilterDelayBlocks(),
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aec_state.ReverbDecay(), R2);
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}
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} else {
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// Estimate the echo generating signal power.
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std::array<float, kFftLengthBy2Plus1> X2;
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EchoGeneratingPower(render_buffer.GetSpectrumBuffer(), config_.echo_model,
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render_buffer.Headroom(), aec_state.FilterDelayBlocks(),
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aec_state.IsSuppressionGainLimitActive(),
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!aec_state.UseStationaryProperties(), &X2);
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// Subtract the stationary noise power to avoid stationary noise causing
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// excessive echo suppression.
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std::transform(X2.begin(), X2.end(), X2_noise_floor_.begin(), X2.begin(),
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[&](float a, float b) {
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return std::max(
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0.f, a - config_.echo_model.stationary_gate_slope * b);
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});
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float echo_path_gain;
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if (override_estimated_echo_path_gain_) {
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echo_path_gain = aec_state.TransparentMode() && soft_transparent_mode_
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? 0.01f
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: config_.ep_strength.lf;
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} else {
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echo_path_gain = aec_state.TransparentMode() && soft_transparent_mode_
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? 0.01f
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: aec_state.EchoPathGain();
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}
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NonLinearEstimate(echo_path_gain, X2, Y2, R2);
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// If the echo is saturated, estimate the echo power as the maximum echo
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// power with a leakage factor.
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if (aec_state.SaturatedEcho()) {
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R2->fill((*std::max_element(R2->begin(), R2->end())) * 100.f);
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}
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if (!(aec_state.TransparentMode() && soft_transparent_mode_)) {
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if (echo_reverb_) {
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echo_reverb_->AddReverb(
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render_buffer.Spectrum(aec_state.FilterDelayBlocks() + 1),
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echo_path_gain * echo_path_gain, aec_state.ReverbDecay(), *R2);
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} else {
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RTC_DCHECK(echo_reverb_fallback);
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echo_reverb_fallback->AddEchoReverb(*R2,
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config_.filter.main.length_blocks,
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aec_state.ReverbDecay(), R2);
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}
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}
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}
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if (aec_state.UseStationaryProperties()) {
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// Scale the echo according to echo audibility.
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std::array<float, kFftLengthBy2Plus1> residual_scaling;
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aec_state.GetResidualEchoScaling(residual_scaling);
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for (size_t k = 0; k < R2->size(); ++k) {
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(*R2)[k] *= residual_scaling[k];
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if (residual_scaling[k] == 0.f) {
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R2_hold_counter_[k] = 0;
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}
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}
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}
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if (!soft_transparent_mode_) {
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// If the echo is deemed inaudible, set the residual echo to zero.
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if (aec_state.TransparentMode()) {
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R2->fill(0.f);
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R2_old_.fill(0.f);
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R2_hold_counter_.fill(0.f);
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}
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}
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std::copy(R2->begin(), R2->end(), R2_old_.begin());
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}
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void ResidualEchoEstimator::Reset() {
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if (echo_reverb_) {
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echo_reverb_->Reset();
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} else {
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RTC_DCHECK(echo_reverb_fallback);
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echo_reverb_fallback->Reset();
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}
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X2_noise_floor_counter_.fill(config_.echo_model.noise_floor_hold);
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X2_noise_floor_.fill(config_.echo_model.min_noise_floor_power);
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R2_old_.fill(0.f);
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R2_hold_counter_.fill(0.f);
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}
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void ResidualEchoEstimator::LinearEstimate(
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const std::array<float, kFftLengthBy2Plus1>& S2_linear,
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const std::array<float, kFftLengthBy2Plus1>& erle,
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std::array<float, kFftLengthBy2Plus1>* R2) {
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std::fill(R2_hold_counter_.begin(), R2_hold_counter_.end(), 10.f);
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std::transform(erle.begin(), erle.end(), S2_linear.begin(), R2->begin(),
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[](float a, float b) {
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RTC_DCHECK_LT(0.f, a);
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return b / a;
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});
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}
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void ResidualEchoEstimator::NonLinearEstimate(
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float echo_path_gain,
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const std::array<float, kFftLengthBy2Plus1>& X2,
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const std::array<float, kFftLengthBy2Plus1>& Y2,
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std::array<float, kFftLengthBy2Plus1>* R2) {
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// Compute preliminary residual echo.
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std::transform(X2.begin(), X2.end(), R2->begin(), [echo_path_gain](float a) {
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return a * echo_path_gain * echo_path_gain;
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});
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for (size_t k = 0; k < R2->size(); ++k) {
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// Update hold counter.
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R2_hold_counter_[k] = R2_old_[k] < (*R2)[k] ? 0 : R2_hold_counter_[k] + 1;
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// Compute the residual echo by holding a maximum echo powers and an echo
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// fading corresponding to a room with an RT60 value of about 50 ms.
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(*R2)[k] =
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R2_hold_counter_[k] < config_.echo_model.nonlinear_hold
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? std::max((*R2)[k], R2_old_[k])
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: std::min(
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(*R2)[k] + R2_old_[k] * config_.echo_model.nonlinear_release,
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Y2[k]);
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}
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}
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void ResidualEchoEstimator::EchoGeneratingPower(
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const VectorBuffer& spectrum_buffer,
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const EchoCanceller3Config::EchoModel& echo_model,
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int headroom_spectrum_buffer,
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int filter_delay_blocks,
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bool gain_limiter_running,
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bool apply_noise_gating,
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std::array<float, kFftLengthBy2Plus1>* X2) const {
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int idx_stop, idx_start;
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RTC_DCHECK(X2);
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GetRenderIndexesToAnalyze(spectrum_buffer, config_.echo_model,
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filter_delay_blocks, gain_limiter_running,
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headroom_spectrum_buffer, &idx_start, &idx_stop);
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X2->fill(0.f);
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for (int k = idx_start; k != idx_stop; k = spectrum_buffer.IncIndex(k)) {
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std::transform(X2->begin(), X2->end(), spectrum_buffer.buffer[k].begin(),
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X2->begin(),
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[](float a, float b) { return std::max(a, b); });
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}
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if (apply_noise_gating) {
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// Apply soft noise gate.
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std::for_each(X2->begin(), X2->end(), [&](float& a) {
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if (config_.echo_model.noise_gate_power > a) {
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a = std::max(0.f, a - config_.echo_model.noise_gate_slope *
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(config_.echo_model.noise_gate_power - a));
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}
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});
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}
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}
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void ResidualEchoEstimator::RenderNoisePower(
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const RenderBuffer& render_buffer,
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std::array<float, kFftLengthBy2Plus1>* X2_noise_floor,
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std::array<int, kFftLengthBy2Plus1>* X2_noise_floor_counter) const {
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RTC_DCHECK(X2_noise_floor);
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RTC_DCHECK(X2_noise_floor_counter);
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const auto render_power = render_buffer.Spectrum(0);
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RTC_DCHECK_EQ(X2_noise_floor->size(), render_power.size());
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RTC_DCHECK_EQ(X2_noise_floor_counter->size(), render_power.size());
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// Estimate the stationary noise power in a minimum statistics manner.
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for (size_t k = 0; k < render_power.size(); ++k) {
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// Decrease rapidly.
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if (render_power[k] < (*X2_noise_floor)[k]) {
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(*X2_noise_floor)[k] = render_power[k];
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(*X2_noise_floor_counter)[k] = 0;
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} else {
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// Increase in a delayed, leaky manner.
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if ((*X2_noise_floor_counter)[k] >=
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static_cast<int>(config_.echo_model.noise_floor_hold)) {
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(*X2_noise_floor)[k] =
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std::max((*X2_noise_floor)[k] * 1.1f,
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config_.echo_model.min_noise_floor_power);
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} else {
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++(*X2_noise_floor_counter)[k];
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}
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}
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}
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}
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} // namespace webrtc
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