Source code
Revision control
Copy as Markdown
Other Tools
/*
* 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 <atomic>
#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/checks.h"
#include "rtc_base/logging.h"
namespace webrtc {
namespace {
// Maximum number of channels for which the capture channel data is stored on
// the stack. If the number of channels are larger than this, they are stored
// using scratch memory that is pre-allocated on the heap. The reason for this
// partitioning is not to waste heap space for handling the more common numbers
// of channels, while at the same time not limiting the support for higher
// numbers of channels by enforcing the capture channel data to be stored on the
// stack using a fixed maximum value.
constexpr size_t kMaxNumChannelsOnStack = 2;
// Chooses the number of channels to store on the heap when that is required due
// to the number of capture channels being larger than the pre-defined number
// of channels to store on the stack.
size_t NumChannelsOnHeap(size_t num_capture_channels) {
return num_capture_channels > kMaxNumChannelsOnStack ? num_capture_channels
: 0;
}
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) {
if (from == to) {
RTC_DCHECK_EQ(to.size(), out.size());
std::copy(to.begin(), to.end(), out.begin());
} else {
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,
size_t num_render_channels,
size_t num_capture_channels);
~EchoRemoverImpl() override;
EchoRemoverImpl(const EchoRemoverImpl&) = delete;
EchoRemoverImpl& operator=(const EchoRemoverImpl&) = delete;
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,
Block* linear_output,
Block* 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;
}
void SetCaptureOutputUsage(bool capture_output_used) override {
capture_output_used_ = capture_output_used;
}
private:
// Selects which of the coarse and refined 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 std::atomic<int> instance_count_;
const EchoCanceller3Config config_;
const Aec3Fft fft_;
std::unique_ptr<ApmDataDumper> data_dumper_;
const Aec3Optimization optimization_;
const int sample_rate_hz_;
const size_t num_render_channels_;
const size_t num_capture_channels_;
const bool use_coarse_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;
bool capture_output_used_ = true;
AecState aec_state_;
EchoRemoverMetrics metrics_;
std::vector<std::array<float, kFftLengthBy2>> e_old_;
std::vector<std::array<float, kFftLengthBy2>> y_old_;
size_t block_counter_ = 0;
int gain_change_hangover_ = 0;
bool refined_filter_output_last_selected_ = true;
std::vector<std::array<float, kFftLengthBy2>> e_heap_;
std::vector<std::array<float, kFftLengthBy2Plus1>> Y2_heap_;
std::vector<std::array<float, kFftLengthBy2Plus1>> E2_heap_;
std::vector<std::array<float, kFftLengthBy2Plus1>> R2_heap_;
std::vector<std::array<float, kFftLengthBy2Plus1>> R2_unbounded_heap_;
std::vector<std::array<float, kFftLengthBy2Plus1>> S2_linear_heap_;
std::vector<FftData> Y_heap_;
std::vector<FftData> E_heap_;
std::vector<FftData> comfort_noise_heap_;
std::vector<FftData> high_band_comfort_noise_heap_;
std::vector<SubtractorOutput> subtractor_output_heap_;
};
std::atomic<int> EchoRemoverImpl::instance_count_(0);
EchoRemoverImpl::EchoRemoverImpl(const EchoCanceller3Config& config,
int sample_rate_hz,
size_t num_render_channels,
size_t num_capture_channels)
: config_(config),
fft_(),
data_dumper_(new ApmDataDumper(instance_count_.fetch_add(1) + 1)),
optimization_(DetectOptimization()),
sample_rate_hz_(sample_rate_hz),
num_render_channels_(num_render_channels),
num_capture_channels_(num_capture_channels),
use_coarse_filter_output_(
config_.filter.enable_coarse_filter_output_usage),
subtractor_(config,
num_render_channels_,
num_capture_channels_,
data_dumper_.get(),
optimization_),
suppression_gain_(config_,
optimization_,
sample_rate_hz,
num_capture_channels),
cng_(config_, optimization_, num_capture_channels_),
suppression_filter_(optimization_,
sample_rate_hz_,
num_capture_channels_),
render_signal_analyzer_(config_),
residual_echo_estimator_(config_, num_render_channels),
aec_state_(config_, num_capture_channels_),
e_old_(num_capture_channels_, {0.f}),
y_old_(num_capture_channels_, {0.f}),
e_heap_(NumChannelsOnHeap(num_capture_channels_), {0.f}),
Y2_heap_(NumChannelsOnHeap(num_capture_channels_)),
E2_heap_(NumChannelsOnHeap(num_capture_channels_)),
R2_heap_(NumChannelsOnHeap(num_capture_channels_)),
R2_unbounded_heap_(NumChannelsOnHeap(num_capture_channels_)),
S2_linear_heap_(NumChannelsOnHeap(num_capture_channels_)),
Y_heap_(NumChannelsOnHeap(num_capture_channels_)),
E_heap_(NumChannelsOnHeap(num_capture_channels_)),
comfort_noise_heap_(NumChannelsOnHeap(num_capture_channels_)),
high_band_comfort_noise_heap_(NumChannelsOnHeap(num_capture_channels_)),
subtractor_output_heap_(NumChannelsOnHeap(num_capture_channels_)) {
RTC_DCHECK(ValidFullBandRate(sample_rate_hz));
}
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,
Block* linear_output,
Block* capture) {
++block_counter_;
const Block& x = render_buffer->GetBlock(0);
Block* y = capture;
RTC_DCHECK(render_buffer);
RTC_DCHECK(y);
RTC_DCHECK_EQ(x.NumBands(), NumBandsForRate(sample_rate_hz_));
RTC_DCHECK_EQ(y->NumBands(), NumBandsForRate(sample_rate_hz_));
RTC_DCHECK_EQ(x.NumChannels(), num_render_channels_);
RTC_DCHECK_EQ(y->NumChannels(), num_capture_channels_);
// Stack allocated data to use when the number of channels is low.
std::array<std::array<float, kFftLengthBy2>, kMaxNumChannelsOnStack> e_stack;
std::array<std::array<float, kFftLengthBy2Plus1>, kMaxNumChannelsOnStack>
Y2_stack;
std::array<std::array<float, kFftLengthBy2Plus1>, kMaxNumChannelsOnStack>
E2_stack;
std::array<std::array<float, kFftLengthBy2Plus1>, kMaxNumChannelsOnStack>
R2_stack;
std::array<std::array<float, kFftLengthBy2Plus1>, kMaxNumChannelsOnStack>
R2_unbounded_stack;
std::array<std::array<float, kFftLengthBy2Plus1>, kMaxNumChannelsOnStack>
S2_linear_stack;
std::array<FftData, kMaxNumChannelsOnStack> Y_stack;
std::array<FftData, kMaxNumChannelsOnStack> E_stack;
std::array<FftData, kMaxNumChannelsOnStack> comfort_noise_stack;
std::array<FftData, kMaxNumChannelsOnStack> high_band_comfort_noise_stack;
std::array<SubtractorOutput, kMaxNumChannelsOnStack> subtractor_output_stack;
rtc::ArrayView<std::array<float, kFftLengthBy2>> e(e_stack.data(),
num_capture_channels_);
rtc::ArrayView<std::array<float, kFftLengthBy2Plus1>> Y2(
Y2_stack.data(), num_capture_channels_);
rtc::ArrayView<std::array<float, kFftLengthBy2Plus1>> E2(
E2_stack.data(), num_capture_channels_);
rtc::ArrayView<std::array<float, kFftLengthBy2Plus1>> R2(
R2_stack.data(), num_capture_channels_);
rtc::ArrayView<std::array<float, kFftLengthBy2Plus1>> R2_unbounded(
R2_unbounded_stack.data(), num_capture_channels_);
rtc::ArrayView<std::array<float, kFftLengthBy2Plus1>> S2_linear(
S2_linear_stack.data(), num_capture_channels_);
rtc::ArrayView<FftData> Y(Y_stack.data(), num_capture_channels_);
rtc::ArrayView<FftData> E(E_stack.data(), num_capture_channels_);
rtc::ArrayView<FftData> comfort_noise(comfort_noise_stack.data(),
num_capture_channels_);
rtc::ArrayView<FftData> high_band_comfort_noise(
high_band_comfort_noise_stack.data(), num_capture_channels_);
rtc::ArrayView<SubtractorOutput> subtractor_output(
subtractor_output_stack.data(), num_capture_channels_);
if (NumChannelsOnHeap(num_capture_channels_) > 0) {
// If the stack-allocated space is too small, use the heap for storing the
// microphone data.
e = rtc::ArrayView<std::array<float, kFftLengthBy2>>(e_heap_.data(),
num_capture_channels_);
Y2 = rtc::ArrayView<std::array<float, kFftLengthBy2Plus1>>(
Y2_heap_.data(), num_capture_channels_);
E2 = rtc::ArrayView<std::array<float, kFftLengthBy2Plus1>>(
E2_heap_.data(), num_capture_channels_);
R2 = rtc::ArrayView<std::array<float, kFftLengthBy2Plus1>>(
R2_heap_.data(), num_capture_channels_);
R2_unbounded = rtc::ArrayView<std::array<float, kFftLengthBy2Plus1>>(
R2_unbounded_heap_.data(), num_capture_channels_);
S2_linear = rtc::ArrayView<std::array<float, kFftLengthBy2Plus1>>(
S2_linear_heap_.data(), num_capture_channels_);
Y = rtc::ArrayView<FftData>(Y_heap_.data(), num_capture_channels_);
E = rtc::ArrayView<FftData>(E_heap_.data(), num_capture_channels_);
comfort_noise = rtc::ArrayView<FftData>(comfort_noise_heap_.data(),
num_capture_channels_);
high_band_comfort_noise = rtc::ArrayView<FftData>(
high_band_comfort_noise_heap_.data(), num_capture_channels_);
subtractor_output = rtc::ArrayView<SubtractorOutput>(
subtractor_output_heap_.data(), num_capture_channels_);
}
data_dumper_->DumpWav("aec3_echo_remover_capture_input",
y->View(/*band=*/0, /*channel=*/0), 16000, 1);
data_dumper_->DumpWav("aec3_echo_remover_render_input",
x.View(/*band=*/0, /*channel=*/0), 16000, 1);
data_dumper_->DumpRaw("aec3_echo_remover_capture_input",
y->View(/*band=*/0, /*channel=*/0));
data_dumper_->DumpRaw("aec3_echo_remover_render_input",
x.View(/*band=*/0, /*channel=*/0));
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::LoggingSeverity log_level =
config_.delay.log_warning_on_delay_changes ? rtc::LS_WARNING
: rtc::LS_VERBOSE;
RTC_LOG_V(log_level)
<< "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_;
}
// Analyze the render signal.
render_signal_analyzer_.Update(*render_buffer,
aec_state_.MinDirectPathFilterDelay());
// State transition.
if (aec_state_.TransitionTriggered()) {
subtractor_.ExitInitialState();
suppression_gain_.SetInitialState(false);
}
// Perform linear echo cancellation.
subtractor_.Process(*render_buffer, *y, render_signal_analyzer_, aec_state_,
subtractor_output);
// Compute spectra.
for (size_t ch = 0; ch < num_capture_channels_; ++ch) {
FormLinearFilterOutput(subtractor_output[ch], e[ch]);
WindowedPaddedFft(fft_, y->View(/*band=*/0, ch), y_old_[ch], &Y[ch]);
WindowedPaddedFft(fft_, e[ch], e_old_[ch], &E[ch]);
LinearEchoPower(E[ch], Y[ch], &S2_linear[ch]);
Y[ch].Spectrum(optimization_, Y2[ch]);
E[ch].Spectrum(optimization_, E2[ch]);
}
// Optionally return the linear filter output.
if (linear_output) {
RTC_DCHECK_GE(1, linear_output->NumBands());
RTC_DCHECK_EQ(num_capture_channels_, linear_output->NumChannels());
for (size_t ch = 0; ch < num_capture_channels_; ++ch) {
std::copy(e[ch].begin(), e[ch].end(),
linear_output->begin(/*band=*/0, ch));
}
}
// Update the AEC state information.
aec_state_.Update(external_delay, subtractor_.FilterFrequencyResponses(),
subtractor_.FilterImpulseResponses(), *render_buffer, E2,
Y2, subtractor_output);
// Choose the linear output.
const auto& Y_fft = aec_state_.UseLinearFilterOutput() ? E : Y;
data_dumper_->DumpWav("aec3_output_linear",
y->View(/*band=*/0, /*channel=*/0), 16000, 1);
data_dumper_->DumpWav("aec3_output_linear2", kBlockSize, &e[0][0], 16000, 1);
// Estimate the comfort noise.
cng_.Compute(aec_state_.SaturatedCapture(), Y2, comfort_noise,
high_band_comfort_noise);
// Only do the below processing if the output of the audio processing module
// is used.
std::array<float, kFftLengthBy2Plus1> G;
if (capture_output_used_) {
// Estimate the residual echo power.
residual_echo_estimator_.Estimate(aec_state_, *render_buffer, S2_linear, Y2,
suppression_gain_.IsDominantNearend(), R2,
R2_unbounded);
// Suppressor nearend estimate.
if (aec_state_.UsableLinearEstimate()) {
// E2 is bound by Y2.
for (size_t ch = 0; ch < num_capture_channels_; ++ch) {
std::transform(E2[ch].begin(), E2[ch].end(), Y2[ch].begin(),
E2[ch].begin(),
[](float a, float b) { return std::min(a, b); });
}
}
const auto& nearend_spectrum = aec_state_.UsableLinearEstimate() ? E2 : Y2;
// Suppressor echo estimate.
const auto& echo_spectrum =
aec_state_.UsableLinearEstimate() ? S2_linear : R2;
// Determine if the suppressor should assume clock drift.
const bool clock_drift = config_.echo_removal_control.has_clock_drift ||
echo_path_variability.clock_drift;
// Compute preferred gains.
float high_bands_gain;
suppression_gain_.GetGain(nearend_spectrum, echo_spectrum, R2, R2_unbounded,
cng_.NoiseSpectrum(), render_signal_analyzer_,
aec_state_, x, clock_drift, &high_bands_gain, &G);
suppression_filter_.ApplyGain(comfort_noise, high_band_comfort_noise, G,
high_bands_gain, Y_fft, y);
} else {
G.fill(0.f);
}
// Update the metrics.
metrics_.Update(aec_state_, cng_.NoiseSpectrum()[0], G);
// Debug outputs for the purpose of development and analysis.
data_dumper_->DumpWav("aec3_echo_estimate", kBlockSize,
&subtractor_output[0].s_refined[0], 16000, 1);
data_dumper_->DumpRaw("aec3_output", y->View(/*band=*/0, /*channel=*/0));
data_dumper_->DumpRaw("aec3_narrow_render",
render_signal_analyzer_.NarrowPeakBand() ? 1 : 0);
data_dumper_->DumpRaw("aec3_N2", cng_.NoiseSpectrum()[0]);
data_dumper_->DumpRaw("aec3_suppressor_gain", G);
data_dumper_->DumpWav("aec3_output", y->View(/*band=*/0, /*channel=*/0),
16000, 1);
data_dumper_->DumpRaw("aec3_using_subtractor_output[0]",
aec_state_.UseLinearFilterOutput() ? 1 : 0);
data_dumper_->DumpRaw("aec3_E2", E2[0]);
data_dumper_->DumpRaw("aec3_S2_linear", S2_linear[0]);
data_dumper_->DumpRaw("aec3_Y2", Y2[0]);
data_dumper_->DumpRaw(
"aec3_X2", render_buffer->Spectrum(
aec_state_.MinDirectPathFilterDelay())[/*channel=*/0]);
data_dumper_->DumpRaw("aec3_R2", R2[0]);
data_dumper_->DumpRaw("aec3_filter_delay",
aec_state_.MinDirectPathFilterDelay());
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_refined.size(), output.size());
RTC_DCHECK_EQ(subtractor_output.e_coarse.size(), output.size());
bool use_refined_output = true;
if (use_coarse_filter_output_) {
// As the output of the refined adaptive filter generally should be better
// than the coarse filter output, add a margin and threshold for when
// choosing the coarse filter output.
if (subtractor_output.e2_coarse < 0.9f * subtractor_output.e2_refined &&
subtractor_output.y2 > 30.f * 30.f * kBlockSize &&
(subtractor_output.s2_refined > 60.f * 60.f * kBlockSize ||
subtractor_output.s2_coarse > 60.f * 60.f * kBlockSize)) {
use_refined_output = false;
} else {
// If the refined filter is diverged, choose the filter output that has
// the lowest power.
if (subtractor_output.e2_coarse < subtractor_output.e2_refined &&
subtractor_output.y2 < subtractor_output.e2_refined) {
use_refined_output = false;
}
}
}
SignalTransition(refined_filter_output_last_selected_
? subtractor_output.e_refined
: subtractor_output.e_coarse,
use_refined_output ? subtractor_output.e_refined
: subtractor_output.e_coarse,
output);
refined_filter_output_last_selected_ = use_refined_output;
}
} // namespace
EchoRemover* EchoRemover::Create(const EchoCanceller3Config& config,
int sample_rate_hz,
size_t num_render_channels,
size_t num_capture_channels) {
return new EchoRemoverImpl(config, sample_rate_hz, num_render_channels,
num_capture_channels);
}
} // namespace webrtc