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/*
* Copyright (c) 2016 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/agc2/noise_spectrum_estimator.h"
#include <string.h>
#include <algorithm>
#include "api/array_view.h"
#include "modules/audio_processing/logging/apm_data_dumper.h"
#include "rtc_base/arraysize.h"
#include "rtc_base/checks.h"
namespace webrtc {
namespace {
constexpr float kMinNoisePower = 100.f;
} // namespace
NoiseSpectrumEstimator::NoiseSpectrumEstimator(ApmDataDumper* data_dumper)
: data_dumper_(data_dumper) {
Initialize();
}
void NoiseSpectrumEstimator::Initialize() {
std::fill(noise_spectrum_, noise_spectrum_ + arraysize(noise_spectrum_),
kMinNoisePower);
}
void NoiseSpectrumEstimator::Update(rtc::ArrayView<const float> spectrum,
bool first_update) {
RTC_DCHECK_EQ(65, spectrum.size());
if (first_update) {
// Initialize the noise spectral estimate with the signal spectrum.
std::copy(spectrum.data(), spectrum.data() + spectrum.size(),
noise_spectrum_);
} else {
// Smoothly update the noise spectral estimate towards the signal spectrum
// such that the magnitude of the updates are limited.
for (size_t k = 0; k < spectrum.size(); ++k) {
if (noise_spectrum_[k] < spectrum[k]) {
noise_spectrum_[k] = std::min(
1.01f * noise_spectrum_[k],
noise_spectrum_[k] + 0.05f * (spectrum[k] - noise_spectrum_[k]));
} else {
noise_spectrum_[k] = std::max(
0.99f * noise_spectrum_[k],
noise_spectrum_[k] + 0.05f * (spectrum[k] - noise_spectrum_[k]));
}
}
}
// Ensure that the noise spectal estimate does not become too low.
for (auto& v : noise_spectrum_) {
v = std::max(v, kMinNoisePower);
}
data_dumper_->DumpRaw("lc_noise_spectrum", 65, noise_spectrum_);
data_dumper_->DumpRaw("lc_signal_spectrum", spectrum);
}
} // namespace webrtc
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