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169c7fd521da7530ea55f9c4d4d045ccfd952e18
platform-external-webrtc/modules/audio_processing/aec3/echo_remover.cc
Per Åhgren 169c7fd521 Use windowed, data padded, FFTs when computing the AEC3 suppressor gain 
This CL changes the way the suppressor gain is computed in AEC3 in that
the FFTs used are padded with data and windowed with a Hanning-style
window.
This gives better FFT accuracy, an behavior matching the suppressor
gain application, and also results in one less FFT operation.

Bug: webrtc:9204,chromium:837563
Change-Id: I612676c389cb76a3130966a9b596ff3f44d21863
Reviewed-on: https://webrtc-review.googlesource.com/73141
Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org>
Commit-Queue: Per Åhgren <peah@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23057}
2018-04-27 14:47:56 +00:00

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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 "modules/audio_processing/aec3/echo_remover.h"
#include <math.h>
#include <algorithm>
#include <memory>
#include <numeric>
#include <string>
#include "api/array_view.h"
#include "modules/audio_processing/aec3/aec3_common.h"
#include "modules/audio_processing/aec3/aec_state.h"
#include "modules/audio_processing/aec3/comfort_noise_generator.h"
#include "modules/audio_processing/aec3/echo_path_variability.h"
#include "modules/audio_processing/aec3/echo_remover_metrics.h"
#include "modules/audio_processing/aec3/fft_data.h"
#include "modules/audio_processing/aec3/render_buffer.h"
#include "modules/audio_processing/aec3/render_delay_buffer.h"
#include "modules/audio_processing/aec3/residual_echo_estimator.h"
#include "modules/audio_processing/aec3/subtractor.h"
#include "modules/audio_processing/aec3/suppression_filter.h"
#include "modules/audio_processing/aec3/suppression_gain.h"
#include "modules/audio_processing/logging/apm_data_dumper.h"
#include "rtc_base/atomicops.h"
#include "rtc_base/constructormagic.h"
namespace webrtc {
namespace {
void LinearEchoPower(const FftData& E,
const FftData& Y,
std::array<float, kFftLengthBy2Plus1>* S2) {
for (size_t k = 0; k < E.re.size(); ++k) {
(*S2)[k] = (Y.re[k] - E.re[k]) * (Y.re[k] - E.re[k]) +
(Y.im[k] - E.im[k]) * (Y.im[k] - E.im[k]);
}
}
// Computes a windowed (square root Hanning) padded FFT and updates the related
// memory.
void WindowedPaddedFft(const Aec3Fft& fft,
rtc::ArrayView<const float> v,
rtc::ArrayView<float> v_old,
FftData* V) {
fft.PaddedFft(v, v_old, Aec3Fft::Window::kSqrtHanning, V);
std::copy(v.begin(), v.end(), v_old.begin());
}
// Class for removing the echo from the capture signal.
class EchoRemoverImpl final : public EchoRemover {
public:
EchoRemoverImpl(const EchoCanceller3Config& config, int sample_rate_hz);
~EchoRemoverImpl() override;
void GetMetrics(EchoControl::Metrics* metrics) const override;
// Removes the echo from a block of samples from the capture signal. The
// supplied render signal is assumed to be pre-aligned with the capture
// signal.
void ProcessCapture(const EchoPathVariability& echo_path_variability,
bool capture_signal_saturation,
const rtc::Optional<DelayEstimate>& external_delay,
RenderBuffer* render_buffer,
std::vector<std::vector<float>>* capture) override;
// Returns the internal delay estimate in blocks.
rtc::Optional<int> Delay() const override {
return aec_state_.InternalDelay();
}
// Updates the status on whether echo leakage is detected in the output of the
// echo remover.
void UpdateEchoLeakageStatus(bool leakage_detected) override {
echo_leakage_detected_ = leakage_detected;
}
private:
static int instance_count_;
const EchoCanceller3Config config_;
const Aec3Fft fft_;
std::unique_ptr<ApmDataDumper> data_dumper_;
const Aec3Optimization optimization_;
const int sample_rate_hz_;
Subtractor subtractor_;
SuppressionGain suppression_gain_;
ComfortNoiseGenerator cng_;
SuppressionFilter suppression_filter_;
RenderSignalAnalyzer render_signal_analyzer_;
ResidualEchoEstimator residual_echo_estimator_;
bool echo_leakage_detected_ = false;
AecState aec_state_;
EchoRemoverMetrics metrics_;
bool initial_state_ = true;
std::array<float, kFftLengthBy2> e_old_;
std::array<float, kFftLengthBy2> x_old_;
std::array<float, kFftLengthBy2> y_old_;
RTC_DISALLOW_COPY_AND_ASSIGN(EchoRemoverImpl);
};
int EchoRemoverImpl::instance_count_ = 0;
EchoRemoverImpl::EchoRemoverImpl(const EchoCanceller3Config& config,
int sample_rate_hz)
: config_(config),
fft_(),
data_dumper_(
new ApmDataDumper(rtc::AtomicOps::Increment(&instance_count_))),
optimization_(DetectOptimization()),
sample_rate_hz_(sample_rate_hz),
subtractor_(config, data_dumper_.get(), optimization_),
suppression_gain_(config_, optimization_, sample_rate_hz),
cng_(optimization_),
suppression_filter_(sample_rate_hz_),
render_signal_analyzer_(config_),
residual_echo_estimator_(config_),
aec_state_(config_) {
RTC_DCHECK(ValidFullBandRate(sample_rate_hz));
x_old_.fill(0.f);
y_old_.fill(0.f);
e_old_.fill(0.f);
}
EchoRemoverImpl::~EchoRemoverImpl() = default;
void EchoRemoverImpl::GetMetrics(EchoControl::Metrics* metrics) const {
// Echo return loss (ERL) is inverted to go from gain to attenuation.
metrics->echo_return_loss = -10.0 * log10(aec_state_.ErlTimeDomain());
metrics->echo_return_loss_enhancement =
10.0 * log10(aec_state_.ErleTimeDomain());
}
void EchoRemoverImpl::ProcessCapture(
const EchoPathVariability& echo_path_variability,
bool capture_signal_saturation,
const rtc::Optional<DelayEstimate>& external_delay,
RenderBuffer* render_buffer,
std::vector<std::vector<float>>* capture) {
const std::vector<std::vector<float>>& x = render_buffer->Block(0);
std::vector<std::vector<float>>* y = capture;
RTC_DCHECK(render_buffer);
RTC_DCHECK(y);
RTC_DCHECK_EQ(x.size(), NumBandsForRate(sample_rate_hz_));
RTC_DCHECK_EQ(y->size(), NumBandsForRate(sample_rate_hz_));
RTC_DCHECK_EQ(x[0].size(), kBlockSize);
RTC_DCHECK_EQ((*y)[0].size(), kBlockSize);
const std::vector<float>& x0 = x[0];
std::vector<float>& y0 = (*y)[0];
data_dumper_->DumpWav("aec3_echo_remover_capture_input", kBlockSize, &y0[0],
LowestBandRate(sample_rate_hz_), 1);
data_dumper_->DumpWav("aec3_echo_remover_render_input", kBlockSize, &x0[0],
LowestBandRate(sample_rate_hz_), 1);
data_dumper_->DumpRaw("aec3_echo_remover_capture_input", y0);
data_dumper_->DumpRaw("aec3_echo_remover_render_input", x0);
aec_state_.UpdateCaptureSaturation(capture_signal_saturation);
if (echo_path_variability.AudioPathChanged()) {
subtractor_.HandleEchoPathChange(echo_path_variability);
aec_state_.HandleEchoPathChange(echo_path_variability);
suppression_gain_.SetInitialState(true);
initial_state_ = true;
}
std::array<float, kFftLengthBy2Plus1> Y2;
std::array<float, kFftLengthBy2Plus1> E2;
std::array<float, kFftLengthBy2Plus1> R2;
std::array<float, kFftLengthBy2Plus1> S2_linear;
std::array<float, kFftLengthBy2Plus1> G;
float high_bands_gain;
FftData Y;
FftData E;
FftData comfort_noise;
FftData high_band_comfort_noise;
SubtractorOutput subtractor_output;
// Analyze the render signal.
render_signal_analyzer_.Update(*render_buffer,
aec_state_.FilterDelayBlocks());
// Perform linear echo cancellation.
if (initial_state_ && !aec_state_.InitialState()) {
subtractor_.ExitInitialState();
suppression_gain_.SetInitialState(false);
initial_state_ = false;
}
// If the delay is known, use the echo subtractor.
subtractor_.Process(*render_buffer, y0, render_signal_analyzer_, aec_state_,
&subtractor_output);
const auto& e = subtractor_output.e_main;
// Compute spectra.
WindowedPaddedFft(fft_, y0, y_old_, &Y);
WindowedPaddedFft(fft_, e, e_old_, &E);
LinearEchoPower(E, Y, &S2_linear);
Y.Spectrum(optimization_, Y2);
E.Spectrum(optimization_, E2);
// Update the AEC state information.
aec_state_.Update(external_delay, subtractor_.FilterFrequencyResponse(),
subtractor_.FilterImpulseResponse(),
subtractor_.ConvergedFilter(), subtractor_.DivergedFilter(),
*render_buffer, E2, Y2, subtractor_output.s_main);
// Compute spectra.
const bool suppression_gain_uses_ffts =
config_.suppressor.bands_with_reliable_coherence > 0;
FftData X;
if (suppression_gain_uses_ffts) {
auto& x_aligned = render_buffer->Block(-aec_state_.FilterDelayBlocks())[0];
WindowedPaddedFft(fft_, x_aligned, x_old_, &X);
} else {
X.Clear();
}
// Choose the linear output.
data_dumper_->DumpWav("aec3_output_linear2", kBlockSize, &e[0],
LowestBandRate(sample_rate_hz_), 1);
if (aec_state_.UseLinearFilterOutput()) {
std::copy(e.begin(), e.end(), y0.begin());
}
const auto& Y_fft = aec_state_.UseLinearFilterOutput() ? E : Y;
data_dumper_->DumpWav("aec3_output_linear", kBlockSize, &y0[0],
LowestBandRate(sample_rate_hz_), 1);
// Estimate the residual echo power.
residual_echo_estimator_.Estimate(aec_state_, *render_buffer, S2_linear, Y2,
&R2);
// Estimate the comfort noise.
cng_.Compute(aec_state_, Y2, &comfort_noise, &high_band_comfort_noise);
// Compute and apply the suppression gain.
suppression_gain_.GetGain(E2, R2, cng_.NoiseSpectrum(), E, X, Y,
render_signal_analyzer_, aec_state_, x,
&high_bands_gain, &G);
suppression_filter_.ApplyGain(comfort_noise, high_band_comfort_noise, G,
high_bands_gain, Y_fft, y);
// Update the metrics.
metrics_.Update(aec_state_, cng_.NoiseSpectrum(), G);
// Debug outputs for the purpose of development and analysis.
data_dumper_->DumpWav("aec3_echo_estimate", kBlockSize,
&subtractor_output.s_main[0],
LowestBandRate(sample_rate_hz_), 1);
data_dumper_->DumpRaw("aec3_output", y0);
data_dumper_->DumpRaw("aec3_narrow_render",
render_signal_analyzer_.NarrowPeakBand() ? 1 : 0);
data_dumper_->DumpRaw("aec3_N2", cng_.NoiseSpectrum());
data_dumper_->DumpRaw("aec3_suppressor_gain", G);
data_dumper_->DumpWav("aec3_output",
rtc::ArrayView<const float>(&y0[0], kBlockSize),
LowestBandRate(sample_rate_hz_), 1);
data_dumper_->DumpRaw("aec3_using_subtractor_output",
aec_state_.UseLinearFilterOutput() ? 1 : 0);
data_dumper_->DumpRaw("aec3_E2", E2);
data_dumper_->DumpRaw("aec3_S2_linear", S2_linear);
data_dumper_->DumpRaw("aec3_Y2", Y2);
data_dumper_->DumpRaw(
"aec3_X2", render_buffer->Spectrum(aec_state_.FilterDelayBlocks()));
data_dumper_->DumpRaw("aec3_R2", R2);
data_dumper_->DumpRaw("aec3_filter_delay", aec_state_.FilterDelayBlocks());
data_dumper_->DumpRaw("aec3_capture_saturation",
aec_state_.SaturatedCapture() ? 1 : 0);
}
} // namespace
EchoRemover* EchoRemover::Create(const EchoCanceller3Config& config,
int sample_rate_hz) {
return new EchoRemoverImpl(config, sample_rate_hz);
}
} // namespace webrtc
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