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/*
* Copyright (c) 2019 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/subband_nearend_detector.h"
#include <numeric>
namespace webrtc {
SubbandNearendDetector::SubbandNearendDetector(
const EchoCanceller3Config::Suppressor::SubbandNearendDetection& config,
size_t num_capture_channels)
: config_(config),
num_capture_channels_(num_capture_channels),
nearend_smoothers_(num_capture_channels_,
aec3::MovingAverage(kFftLengthBy2Plus1,
config_.nearend_average_blocks)),
one_over_subband_length1_(
1.f / (config_.subband1.high - config_.subband1.low + 1)),
one_over_subband_length2_(
1.f / (config_.subband2.high - config_.subband2.low + 1)) {}
void SubbandNearendDetector::Update(
rtc::ArrayView<const std::array<float, kFftLengthBy2Plus1>>
nearend_spectrum,
rtc::ArrayView<const std::array<float, kFftLengthBy2Plus1>>
residual_echo_spectrum,
rtc::ArrayView<const std::array<float, kFftLengthBy2Plus1>>
comfort_noise_spectrum,
bool initial_state) {
nearend_state_ = false;
for (size_t ch = 0; ch < num_capture_channels_; ++ch) {
const std::array<float, kFftLengthBy2Plus1>& noise =
comfort_noise_spectrum[ch];
std::array<float, kFftLengthBy2Plus1> nearend;
nearend_smoothers_[ch].Average(nearend_spectrum[ch], nearend);
// Noise power of the first region.
float noise_power =
std::accumulate(noise.begin() + config_.subband1.low,
noise.begin() + config_.subband1.high + 1, 0.f) *
one_over_subband_length1_;
// Nearend power of the first region.
float nearend_power_subband1 =
std::accumulate(nearend.begin() + config_.subband1.low,
nearend.begin() + config_.subband1.high + 1, 0.f) *
one_over_subband_length1_;
// Nearend power of the second region.
float nearend_power_subband2 =
std::accumulate(nearend.begin() + config_.subband2.low,
nearend.begin() + config_.subband2.high + 1, 0.f) *
one_over_subband_length2_;
// One channel is sufficient to trigger nearend state.
nearend_state_ =
nearend_state_ ||
(nearend_power_subband1 <
config_.nearend_threshold * nearend_power_subband2 &&
(nearend_power_subband1 > config_.snr_threshold * noise_power));
}
}
} // namespace webrtc