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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/erle_estimator.h"
#include <algorithm>
#include "rtc_base/safe_minmax.h"
namespace webrtc {
ErleEstimator::ErleEstimator(float min_erle,
float max_erle_lf,
float max_erle_hf)
: min_erle_(min_erle),
max_erle_lf_(max_erle_lf),
max_erle_hf_(max_erle_hf) {
erle_.fill(min_erle_);
hold_counters_.fill(0);
}
ErleEstimator::~ErleEstimator() = default;
void ErleEstimator::Update(
const std::array<float, kFftLengthBy2Plus1>& render_spectrum,
const std::array<float, kFftLengthBy2Plus1>& capture_spectrum,
const std::array<float, kFftLengthBy2Plus1>& subtractor_spectrum) {
const auto& X2 = render_spectrum;
const auto& Y2 = capture_spectrum;
const auto& E2 = subtractor_spectrum;
// Corresponds of WGN of power -46 dBFS.
constexpr float kX2Min = 44015068.0f;
// Update the estimates in a clamped minimum statistics manner.
auto erle_update = [&](size_t start, size_t stop, float max_erle) {
for (size_t k = start; k < stop; ++k) {
if (X2[k] > kX2Min && E2[k] > 0.f) {
const float new_erle = Y2[k] / E2[k];
if (new_erle > erle_[k]) {
hold_counters_[k - 1] = 100;
erle_[k] += 0.1f * (new_erle - erle_[k]);
erle_[k] = rtc::SafeClamp(erle_[k], min_erle_, max_erle);
}
}
}
};
erle_update(1, kFftLengthBy2 / 2, max_erle_lf_);
erle_update(kFftLengthBy2 / 2, kFftLengthBy2, max_erle_hf_);
std::for_each(hold_counters_.begin(), hold_counters_.end(),
[](int& a) { --a; });
std::transform(hold_counters_.begin(), hold_counters_.end(),
erle_.begin() + 1, erle_.begin() + 1, [&](int a, float b) {
return a > 0 ? b : std::max(min_erle_, 0.97f * b);
});
erle_[0] = erle_[1];
erle_[kFftLengthBy2] = erle_[kFftLengthBy2 - 1];
}
} // namespace webrtc