blob: 25bb5be6888766ed7704cb922cb3b4c995810040 [file] [log] [blame]
/*
* 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/aec_state.h"
#include <math.h>
#include <numeric>
#include <vector>
#include "api/array_view.h"
#include "modules/audio_processing/logging/apm_data_dumper.h"
#include "rtc_base/atomicops.h"
#include "rtc_base/checks.h"
namespace webrtc {
namespace {
// Computes delay of the adaptive filter.
int EstimateFilterDelay(
const std::vector<std::array<float, kFftLengthBy2Plus1>>&
adaptive_filter_frequency_response) {
const auto& H2 = adaptive_filter_frequency_response;
constexpr size_t kUpperBin = kFftLengthBy2 - 5;
RTC_DCHECK_GE(kMaxAdaptiveFilterLength, H2.size());
std::array<int, kMaxAdaptiveFilterLength> delays;
delays.fill(0);
for (size_t k = 1; k < kUpperBin; ++k) {
// Find the maximum of H2[j].
size_t peak = 0;
for (size_t j = 0; j < H2.size(); ++j) {
if (H2[j][k] > H2[peak][k]) {
peak = j;
}
}
++delays[peak];
}
return std::distance(delays.begin(),
std::max_element(delays.begin(), delays.end()));
}
} // namespace
int AecState::instance_count_ = 0;
AecState::AecState(const EchoCanceller3Config& config)
: data_dumper_(
new ApmDataDumper(rtc::AtomicOps::Increment(&instance_count_))),
erle_estimator_(config.erle.min, config.erle.max_l, config.erle.max_h),
config_(config),
max_render_(config_.filter.length_blocks, 0.f),
reverb_decay_(config_.ep_strength.default_len) {}
AecState::~AecState() = default;
void AecState::HandleEchoPathChange(
const EchoPathVariability& echo_path_variability) {
const auto full_reset = [&]() {
blocks_since_last_saturation_ = 0;
usable_linear_estimate_ = false;
echo_leakage_detected_ = false;
capture_signal_saturation_ = false;
echo_saturation_ = false;
previous_max_sample_ = 0.f;
std::fill(max_render_.begin(), max_render_.end(), 0.f);
force_zero_gain_counter_ = 0;
blocks_with_proper_filter_adaptation_ = 0;
capture_block_counter_ = 0;
filter_has_had_time_to_converge_ = false;
render_received_ = false;
force_zero_gain_ = true;
blocks_with_active_render_ = 0;
};
// TODO(peah): Refine the reset scheme according to the type of gain and
// delay adjustment.
if (echo_path_variability.gain_change) {
full_reset();
}
if (echo_path_variability.delay_change !=
EchoPathVariability::DelayAdjustment::kBufferReadjustment) {
full_reset();
} else if (echo_path_variability.delay_change !=
EchoPathVariability::DelayAdjustment::kBufferFlush) {
full_reset();
} else if (echo_path_variability.delay_change !=
EchoPathVariability::DelayAdjustment::kDelayReset) {
full_reset();
} else if (echo_path_variability.delay_change !=
EchoPathVariability::DelayAdjustment::kNewDetectedDelay) {
full_reset();
} else if (echo_path_variability.gain_change) {
capture_block_counter_ = kNumBlocksPerSecond;
}
}
void AecState::Update(
const std::vector<std::array<float, kFftLengthBy2Plus1>>&
adaptive_filter_frequency_response,
const std::vector<float>& adaptive_filter_impulse_response,
bool converged_filter,
const RenderBuffer& render_buffer,
const std::array<float, kFftLengthBy2Plus1>& E2_main,
const std::array<float, kFftLengthBy2Plus1>& Y2,
const std::array<float, kBlockSize>& s,
bool echo_leakage_detected) {
// Store input parameters.
echo_leakage_detected_ = echo_leakage_detected;
// Estimate the filter delay.
filter_delay_ = EstimateFilterDelay(adaptive_filter_frequency_response);
const std::vector<float>& x = render_buffer.Block(-filter_delay_)[0];
// Update counters.
++capture_block_counter_;
const bool active_render_block = DetectActiveRender(x);
blocks_with_active_render_ += active_render_block ? 1 : 0;
blocks_with_proper_filter_adaptation_ +=
active_render_block && !SaturatedCapture() ? 1 : 0;
// Force zero echo suppression gain after an echo path change to allow at
// least some render data to be collected in order to avoid an initial echo
// burst.
force_zero_gain_ = ++force_zero_gain_counter_ < kNumBlocksPerSecond / 5;
// Update the ERL and ERLE measures.
if (converged_filter && capture_block_counter_ >= 2 * kNumBlocksPerSecond) {
const auto& X2 = render_buffer.Spectrum(filter_delay_);
erle_estimator_.Update(X2, Y2, E2_main);
erl_estimator_.Update(X2, Y2);
}
// Update the echo audibility evaluator.
echo_audibility_.Update(x, s, converged_filter);
// Detect and flag echo saturation.
// TODO(peah): Add the delay in this computation to ensure that the render and
// capture signals are properly aligned.
if (config_.ep_strength.echo_can_saturate) {
echo_saturation_ = DetectEchoSaturation(x);
}
// TODO(peah): Move?
filter_has_had_time_to_converge_ =
blocks_with_proper_filter_adaptation_ >= 2 * kNumBlocksPerSecond;
// Flag whether the linear filter estimate is usable.
usable_linear_estimate_ =
!echo_saturation_ &&
(converged_filter || filter_has_had_time_to_converge_) &&
capture_block_counter_ >= 2 * kNumBlocksPerSecond && !TransparentMode();
// After an amount of active render samples for which an echo should have been
// detected in the capture signal if the ERL was not infinite, flag that a
// transparent mode should be entered.
transparent_mode_ =
!converged_filter &&
(blocks_with_active_render_ == 0 ||
blocks_with_proper_filter_adaptation_ >= 5 * kNumBlocksPerSecond);
// Update the room reverb estimate.
UpdateReverb(adaptive_filter_impulse_response);
}
void AecState::UpdateReverb(const std::vector<float>& impulse_response) {
if ((!(filter_delay_ && usable_linear_estimate_)) ||
(filter_delay_ > static_cast<int>(config_.filter.length_blocks) - 4)) {
return;
}
// Form the data to match against by squaring the impulse response
// coefficients.
std::array<float, GetTimeDomainLength(kMaxAdaptiveFilterLength)>
matching_data_data;
RTC_DCHECK_LE(GetTimeDomainLength(config_.filter.length_blocks),
matching_data_data.size());
rtc::ArrayView<float> matching_data(
matching_data_data.data(),
GetTimeDomainLength(config_.filter.length_blocks));
std::transform(impulse_response.begin(), impulse_response.end(),
matching_data.begin(), [](float a) { return a * a; });
// Avoid matching against noise in the model by subtracting an estimate of the
// model noise power.
constexpr size_t kTailLength = 64;
const size_t tail_index =
GetTimeDomainLength(config_.filter.length_blocks) - kTailLength;
const float tail_power = *std::max_element(matching_data.begin() + tail_index,
matching_data.end());
std::for_each(matching_data.begin(), matching_data.begin() + tail_index,
[tail_power](float& a) { a = std::max(0.f, a - tail_power); });
// Identify the peak index of the impulse response.
const size_t peak_index = *std::max_element(
matching_data.begin(), matching_data.begin() + tail_index);
if (peak_index + 128 < tail_index) {
size_t start_index = peak_index + 64;
// Compute the matching residual error for the current candidate to match.
float residual_sqr_sum = 0.f;
float d_k = reverb_decay_to_test_;
for (size_t k = start_index; k < tail_index; ++k) {
if (matching_data[start_index + 1] == 0.f) {
break;
}
float residual = matching_data[k] - matching_data[peak_index] * d_k;
residual_sqr_sum += residual * residual;
d_k *= reverb_decay_to_test_;
}
// If needed, update the best candidate for the reverb decay.
if (reverb_decay_candidate_residual_ < 0.f ||
residual_sqr_sum < reverb_decay_candidate_residual_) {
reverb_decay_candidate_residual_ = residual_sqr_sum;
reverb_decay_candidate_ = reverb_decay_to_test_;
}
}
// Compute the next reverb candidate to evaluate such that all candidates will
// be evaluated within one second.
reverb_decay_to_test_ += (0.9965f - 0.9f) / (5 * kNumBlocksPerSecond);
// If all reverb candidates have been evaluated, choose the best one as the
// reverb decay.
if (reverb_decay_to_test_ >= 0.9965f) {
if (reverb_decay_candidate_residual_ < 0.f) {
// Transform the decay to be in the unit of blocks.
reverb_decay_ = powf(reverb_decay_candidate_, kFftLengthBy2);
// Limit the estimated reverb_decay_ to the maximum one needed in practice
// to minimize the impact of incorrect estimates.
reverb_decay_ = std::min(config_.ep_strength.default_len, reverb_decay_);
}
reverb_decay_to_test_ = 0.9f;
reverb_decay_candidate_residual_ = -1.f;
}
// For noisy impulse responses, assume a fixed tail length.
if (tail_power > 0.0005f) {
reverb_decay_ = config_.ep_strength.default_len;
}
data_dumper_->DumpRaw("aec3_reverb_decay", reverb_decay_);
data_dumper_->DumpRaw("aec3_tail_power", tail_power);
}
bool AecState::DetectActiveRender(rtc::ArrayView<const float> x) const {
const float x_energy = std::inner_product(x.begin(), x.end(), x.begin(), 0.f);
return x_energy > (config_.render_levels.active_render_limit *
config_.render_levels.active_render_limit) *
kFftLengthBy2;
}
bool AecState::DetectEchoSaturation(rtc::ArrayView<const float> x) {
RTC_DCHECK_LT(0, x.size());
const float max_sample = fabs(*std::max_element(
x.begin(), x.end(), [](float a, float b) { return a * a < b * b; }));
previous_max_sample_ = max_sample;
// Set flag for potential presence of saturated echo
blocks_since_last_saturation_ =
previous_max_sample_ > 200.f && SaturatedCapture()
? 0
: blocks_since_last_saturation_ + 1;
return blocks_since_last_saturation_ < 20;
}
void AecState::EchoAudibility::Update(rtc::ArrayView<const float> x,
const std::array<float, kBlockSize>& s,
bool converged_filter) {
auto result_x = std::minmax_element(x.begin(), x.end());
auto result_s = std::minmax_element(s.begin(), s.end());
const float x_abs =
std::max(fabsf(*result_x.first), fabsf(*result_x.second));
const float s_abs =
std::max(fabsf(*result_s.first), fabsf(*result_s.second));
if (converged_filter) {
if (x_abs < 20.f) {
++low_farend_counter_;
} else {
low_farend_counter_ = 0;
}
} else {
if (x_abs < 100.f) {
++low_farend_counter_;
} else {
low_farend_counter_ = 0;
}
}
// The echo is deemed as not audible if the echo estimate is on the level of
// the quantization noise in the FFTs and the nearend level is sufficiently
// strong to mask that by ensuring that the playout and AGC gains do not boost
// any residual echo that is below the quantization noise level. Furthermore,
// cases where the render signal is very close to zero are also identified as
// not producing audible echo.
inaudible_echo_ = (max_nearend_ > 500 && s_abs < 30.f) ||
(!converged_filter && x_abs < 500);
inaudible_echo_ = inaudible_echo_ || low_farend_counter_ > 20;
}
void AecState::EchoAudibility::UpdateWithOutput(rtc::ArrayView<const float> e) {
const float e_max = *std::max_element(e.begin(), e.end());
const float e_min = *std::min_element(e.begin(), e.end());
const float e_abs = std::max(fabsf(e_max), fabsf(e_min));
if (max_nearend_ < e_abs) {
max_nearend_ = e_abs;
max_nearend_counter_ = 0;
} else {
if (++max_nearend_counter_ > 5 * kNumBlocksPerSecond) {
max_nearend_ *= 0.995f;
}
}
}
} // namespace webrtc