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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 <stddef.h>
#include <algorithm>
#include <array>
#include <cmath>
#include <memory>
#include "api/array_view.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/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_signal_analyzer.h"
#include "modules/audio_processing/aec3/residual_echo_estimator.h"
#include "modules/audio_processing/aec3/subtractor.h"
#include "modules/audio_processing/aec3/subtractor_output.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/atomic_ops.h"
#include "rtc_base/checks.h"
#include "rtc_base/constructor_magic.h"
#include "rtc_base/logging.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]);
}
}
// Fades between two input signals using a fix-sized transition.
void SignalTransition(rtc::ArrayView<const float> from,
rtc::ArrayView<const float> to,
rtc::ArrayView<float> out) {
constexpr size_t kTransitionSize = 30;
constexpr float kOneByTransitionSizePlusOne = 1.f / (kTransitionSize + 1);
RTC_DCHECK_EQ(from.size(), to.size());
RTC_DCHECK_EQ(from.size(), out.size());
RTC_DCHECK_LE(kTransitionSize, out.size());
for (size_t k = 0; k < kTransitionSize; ++k) {
float a = (k + 1) * kOneByTransitionSizePlusOne;
out[k] = a * to[k] + (1.f - a) * from[k];
}
std::copy(to.begin() + kTransitionSize, to.end(),
out.begin() + kTransitionSize);
}
// 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(EchoPathVariability echo_path_variability,
bool capture_signal_saturation,
const absl::optional<DelayEstimate>& external_delay,
RenderBuffer* render_buffer,
std::vector<std::vector<float>>* capture) override;
// 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:
// Selects which of the shadow and main linear filter outputs that is most
// appropriate to pass to the suppressor and forms the linear filter output by
// smoothly transition between those.
void FormLinearFilterOutput(const SubtractorOutput& subtractor_output,
rtc::ArrayView<float> output);
static int instance_count_;
const EchoCanceller3Config config_;
const Aec3Fft fft_;
std::unique_ptr<ApmDataDumper> data_dumper_;
const Aec3Optimization optimization_;
const int sample_rate_hz_;
const bool use_shadow_filter_output_;
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_;
std::array<float, kFftLengthBy2> e_old_;
std::array<float, kFftLengthBy2> x_old_;
std::array<float, kFftLengthBy2> y_old_;
size_t block_counter_ = 0;
int gain_change_hangover_ = 0;
bool main_filter_output_last_selected_ = true;
bool linear_filter_output_last_selected_ = true;
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),
use_shadow_filter_output_(
config_.filter.enable_shadow_filter_output_usage),
subtractor_(config, data_dumper_.get(), optimization_),
suppression_gain_(config_, optimization_, sample_rate_hz),
cng_(optimization_),
suppression_filter_(optimization_, 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 * std::log10(aec_state_.ErlTimeDomain());
metrics->echo_return_loss_enhancement =
Log2TodB(aec_state_.FullBandErleLog2());
}
void EchoRemoverImpl::ProcessCapture(
EchoPathVariability echo_path_variability,
bool capture_signal_saturation,
const absl::optional<DelayEstimate>& external_delay,
RenderBuffer* render_buffer,
std::vector<std::vector<float>>* capture) {
++block_counter_;
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()) {
// Ensure that the gain change is only acted on once per frame.
if (echo_path_variability.gain_change) {
if (gain_change_hangover_ == 0) {
constexpr int kMaxBlocksPerFrame = 3;
gain_change_hangover_ = kMaxBlocksPerFrame;
RTC_LOG(LS_INFO) << "Gain change detected at block " << block_counter_;
} else {
echo_path_variability.gain_change = false;
}
}
subtractor_.HandleEchoPathChange(echo_path_variability);
aec_state_.HandleEchoPathChange(echo_path_variability);
if (echo_path_variability.delay_change !=
EchoPathVariability::DelayAdjustment::kNone) {
suppression_gain_.SetInitialState(true);
}
}
if (gain_change_hangover_ > 0) {
--gain_change_hangover_;
}
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 (aec_state_.TransitionTriggered()) {
subtractor_.ExitInitialState();
suppression_gain_.SetInitialState(false);
}
// If the delay is known, use the echo subtractor.
subtractor_.Process(*render_buffer, y0, render_signal_analyzer_, aec_state_,
&subtractor_output);
std::array<float, kBlockSize> e;
FormLinearFilterOutput(subtractor_output, e);
// 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(), *render_buffer, E2, Y2,
subtractor_output, y0);
// Choose the linear output.
data_dumper_->DumpWav("aec3_output_linear2", kBlockSize, &e[0],
LowestBandRate(sample_rate_hz_), 1);
if (aec_state_.UseLinearFilterOutput()) {
if (!linear_filter_output_last_selected_) {
SignalTransition(y0, e, y0);
} else {
std::copy(e.begin(), e.end(), y0.begin());
}
} else {
if (linear_filter_output_last_selected_) {
SignalTransition(e, y0, y0);
}
}
linear_filter_output_last_selected_ = aec_state_.UseLinearFilterOutput();
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);
// Suppressor echo estimate.
const auto& echo_spectrum =
aec_state_.UsableLinearEstimate() ? S2_linear : R2;
// Suppressor nearend estimate.
std::array<float, kFftLengthBy2Plus1> nearend_spectrum_bounded;
if (aec_state_.UsableLinearEstimate()) {
std::transform(E2.begin(), E2.end(), Y2.begin(),
nearend_spectrum_bounded.begin(),
[](float a, float b) { return std::min(a, b); });
}
auto& nearend_spectrum =
aec_state_.UsableLinearEstimate() ? nearend_spectrum_bounded : Y2;
// Compute and apply the suppression gain.
suppression_gain_.GetGain(nearend_spectrum, echo_spectrum, R2,
cng_.NoiseSpectrum(), 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_R2_reverb",
residual_echo_estimator_.GetReverbPowerSpectrum());
data_dumper_->DumpRaw("aec3_filter_delay", aec_state_.FilterDelayBlocks());
data_dumper_->DumpRaw("aec3_capture_saturation",
aec_state_.SaturatedCapture() ? 1 : 0);
}
void EchoRemoverImpl::FormLinearFilterOutput(
const SubtractorOutput& subtractor_output,
rtc::ArrayView<float> output) {
RTC_DCHECK_EQ(subtractor_output.e_main.size(), output.size());
RTC_DCHECK_EQ(subtractor_output.e_shadow.size(), output.size());
bool use_main_output = true;
if (use_shadow_filter_output_) {
// As the output of the main adaptive filter generally should be better
// than the shadow filter output, add a margin and threshold for when
// choosing the shadow filter output.
if (subtractor_output.e2_shadow < 0.9f * subtractor_output.e2_main &&
subtractor_output.y2 > 30.f * 30.f * kBlockSize &&
(subtractor_output.s2_main > 60.f * 60.f * kBlockSize ||
subtractor_output.s2_shadow > 60.f * 60.f * kBlockSize)) {
use_main_output = false;
} else {
// If the main filter is diverged, choose the filter output that has the
// lowest power.
if (subtractor_output.e2_shadow < subtractor_output.e2_main &&
subtractor_output.y2 < subtractor_output.e2_main) {
use_main_output = false;
}
}
}
if (use_main_output) {
if (!main_filter_output_last_selected_) {
SignalTransition(subtractor_output.e_shadow, subtractor_output.e_main,
output);
} else {
std::copy(subtractor_output.e_main.begin(),
subtractor_output.e_main.end(), output.begin());
}
} else {
if (main_filter_output_last_selected_) {
SignalTransition(subtractor_output.e_main, subtractor_output.e_shadow,
output);
} else {
std::copy(subtractor_output.e_shadow.begin(),
subtractor_output.e_shadow.end(), output.begin());
}
}
main_filter_output_last_selected_ = use_main_output;
}
} // namespace
EchoRemover* EchoRemover::Create(const EchoCanceller3Config& config,
int sample_rate_hz) {
return new EchoRemoverImpl(config, sample_rate_hz);
}
} // namespace webrtc