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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/erl_estimator.h"
#include <algorithm>
#include <numeric>
#include "rtc_base/checks.h"
namespace webrtc {
namespace {
constexpr float kMinErl = 0.01f;
constexpr float kMaxErl = 1000.f;
} // namespace
ErlEstimator::ErlEstimator(size_t startup_phase_length_blocks_)
: startup_phase_length_blocks__(startup_phase_length_blocks_) {
erl_.fill(kMaxErl);
hold_counters_.fill(0);
erl_time_domain_ = kMaxErl;
hold_counter_time_domain_ = 0;
}
ErlEstimator::~ErlEstimator() = default;
void ErlEstimator::Reset() {
blocks_since_reset_ = 0;
}
void ErlEstimator::Update(
const std::vector<bool>& converged_filters,
ArrayView<const std::array<float, kFftLengthBy2Plus1>> render_spectra,
ArrayView<const std::array<float, kFftLengthBy2Plus1>> capture_spectra) {
const size_t num_capture_channels = converged_filters.size();
RTC_DCHECK_EQ(capture_spectra.size(), num_capture_channels);
// Corresponds to WGN of power -46 dBFS.
constexpr float kX2Min = 44015068.0f;
const auto first_converged_iter =
std::find(converged_filters.begin(), converged_filters.end(), true);
const bool any_filter_converged =
first_converged_iter != converged_filters.end();
if (++blocks_since_reset_ < startup_phase_length_blocks__ ||
!any_filter_converged) {
return;
}
// Use the maximum spectrum across capture and the maximum across render.
std::array<float, kFftLengthBy2Plus1> max_capture_spectrum_data;
std::array<float, kFftLengthBy2Plus1> max_capture_spectrum =
capture_spectra[/*channel=*/0];
if (num_capture_channels > 1) {
// Initialize using the first channel with a converged filter.
const size_t first_converged =
std::distance(converged_filters.begin(), first_converged_iter);
RTC_DCHECK_GE(first_converged, 0);
RTC_DCHECK_LT(first_converged, num_capture_channels);
max_capture_spectrum_data = capture_spectra[first_converged];
for (size_t ch = first_converged + 1; ch < num_capture_channels; ++ch) {
if (!converged_filters[ch]) {
continue;
}
for (size_t k = 0; k < kFftLengthBy2Plus1; ++k) {
max_capture_spectrum_data[k] =
std::max(max_capture_spectrum_data[k], capture_spectra[ch][k]);
}
}
max_capture_spectrum = max_capture_spectrum_data;
}
const size_t num_render_channels = render_spectra.size();
std::array<float, kFftLengthBy2Plus1> max_render_spectrum_data;
ArrayView<const float, kFftLengthBy2Plus1> max_render_spectrum =
render_spectra[/*channel=*/0];
if (num_render_channels > 1) {
std::copy(render_spectra[0].begin(), render_spectra[0].end(),
max_render_spectrum_data.begin());
for (size_t ch = 1; ch < num_render_channels; ++ch) {
for (size_t k = 0; k < kFftLengthBy2Plus1; ++k) {
max_render_spectrum_data[k] =
std::max(max_render_spectrum_data[k], render_spectra[ch][k]);
}
}
max_render_spectrum = max_render_spectrum_data;
}
const auto& X2 = max_render_spectrum;
const auto& Y2 = max_capture_spectrum;
// Update the estimates in a maximum statistics manner.
for (size_t k = 1; k < kFftLengthBy2; ++k) {
if (X2[k] > kX2Min) {
const float new_erl = Y2[k] / X2[k];
if (new_erl < erl_[k]) {
hold_counters_[k - 1] = 1000;
erl_[k] += 0.1f * (new_erl - erl_[k]);
erl_[k] = std::max(erl_[k], kMinErl);
}
}
}
std::for_each(hold_counters_.begin(), hold_counters_.end(),
[](int& a) { --a; });
std::transform(hold_counters_.begin(), hold_counters_.end(), erl_.begin() + 1,
erl_.begin() + 1, [](int a, float b) {
return a > 0 ? b : std::min(kMaxErl, 2.f * b);
});
erl_[0] = erl_[1];
erl_[kFftLengthBy2] = erl_[kFftLengthBy2 - 1];
// Compute ERL over all frequency bins.
const float X2_sum = std::accumulate(X2.begin(), X2.end(), 0.0f);
if (X2_sum > kX2Min * X2.size()) {
const float Y2_sum = std::accumulate(Y2.begin(), Y2.end(), 0.0f);
const float new_erl = Y2_sum / X2_sum;
if (new_erl < erl_time_domain_) {
hold_counter_time_domain_ = 1000;
erl_time_domain_ += 0.1f * (new_erl - erl_time_domain_);
erl_time_domain_ = std::max(erl_time_domain_, kMinErl);
}
}
--hold_counter_time_domain_;
erl_time_domain_ = (hold_counter_time_domain_ > 0)
? erl_time_domain_
: std::min(kMaxErl, 2.f * erl_time_domain_);
}
} // namespace webrtc
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