1 /*
2 * Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
11 #include "modules/audio_processing/agc2/noise_spectrum_estimator.h"
12
13 #include <string.h>
14
15 #include <algorithm>
16
17 #include "api/array_view.h"
18 #include "modules/audio_processing/logging/apm_data_dumper.h"
19 #include "rtc_base/arraysize.h"
20 #include "rtc_base/checks.h"
21
22 namespace webrtc {
23 namespace {
24 constexpr float kMinNoisePower = 100.f;
25 } // namespace
26
NoiseSpectrumEstimator(ApmDataDumper * data_dumper)27 NoiseSpectrumEstimator::NoiseSpectrumEstimator(ApmDataDumper* data_dumper)
28 : data_dumper_(data_dumper) {
29 Initialize();
30 }
31
Initialize()32 void NoiseSpectrumEstimator::Initialize() {
33 std::fill(noise_spectrum_, noise_spectrum_ + arraysize(noise_spectrum_),
34 kMinNoisePower);
35 }
36
Update(rtc::ArrayView<const float> spectrum,bool first_update)37 void NoiseSpectrumEstimator::Update(rtc::ArrayView<const float> spectrum,
38 bool first_update) {
39 RTC_DCHECK_EQ(65, spectrum.size());
40
41 if (first_update) {
42 // Initialize the noise spectral estimate with the signal spectrum.
43 std::copy(spectrum.data(), spectrum.data() + spectrum.size(),
44 noise_spectrum_);
45 } else {
46 // Smoothly update the noise spectral estimate towards the signal spectrum
47 // such that the magnitude of the updates are limited.
48 for (size_t k = 0; k < spectrum.size(); ++k) {
49 if (noise_spectrum_[k] < spectrum[k]) {
50 noise_spectrum_[k] = std::min(
51 1.01f * noise_spectrum_[k],
52 noise_spectrum_[k] + 0.05f * (spectrum[k] - noise_spectrum_[k]));
53 } else {
54 noise_spectrum_[k] = std::max(
55 0.99f * noise_spectrum_[k],
56 noise_spectrum_[k] + 0.05f * (spectrum[k] - noise_spectrum_[k]));
57 }
58 }
59 }
60
61 // Ensure that the noise spectal estimate does not become too low.
62 for (auto& v : noise_spectrum_) {
63 v = std::max(v, kMinNoisePower);
64 }
65
66 data_dumper_->DumpRaw("lc_noise_spectrum", 65, noise_spectrum_);
67 data_dumper_->DumpRaw("lc_signal_spectrum", spectrum);
68 }
69
70 } // namespace webrtc
71