1 /*
2 * Copyright (c) 2019 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/ns/quantile_noise_estimator.h"
12
13 #include <algorithm>
14
15 #include "modules/audio_processing/ns/fast_math.h"
16
17 namespace webrtc {
18
QuantileNoiseEstimator()19 QuantileNoiseEstimator::QuantileNoiseEstimator() {
20 quantile_.fill(0.f);
21 density_.fill(0.3f);
22 log_quantile_.fill(8.f);
23
24 constexpr float kOneBySimult = 1.f / kSimult;
25 for (size_t i = 0; i < kSimult; ++i) {
26 counter_[i] = floor(kLongStartupPhaseBlocks * (i + 1.f) * kOneBySimult);
27 }
28 }
29
Estimate(rtc::ArrayView<const float,kFftSizeBy2Plus1> signal_spectrum,rtc::ArrayView<float,kFftSizeBy2Plus1> noise_spectrum)30 void QuantileNoiseEstimator::Estimate(
31 rtc::ArrayView<const float, kFftSizeBy2Plus1> signal_spectrum,
32 rtc::ArrayView<float, kFftSizeBy2Plus1> noise_spectrum) {
33 std::array<float, kFftSizeBy2Plus1> log_spectrum;
34 LogApproximation(signal_spectrum, log_spectrum);
35
36 int quantile_index_to_return = -1;
37 // Loop over simultaneous estimates.
38 for (int s = 0, k = 0; s < kSimult;
39 ++s, k += static_cast<int>(kFftSizeBy2Plus1)) {
40 const float one_by_counter_plus_1 = 1.f / (counter_[s] + 1.f);
41 for (int i = 0, j = k; i < static_cast<int>(kFftSizeBy2Plus1); ++i, ++j) {
42 // Update log quantile estimate.
43 const float delta = density_[j] > 1.f ? 40.f / density_[j] : 40.f;
44
45 const float multiplier = delta * one_by_counter_plus_1;
46 if (log_spectrum[i] > log_quantile_[j]) {
47 log_quantile_[j] += 0.25f * multiplier;
48 } else {
49 log_quantile_[j] -= 0.75f * multiplier;
50 }
51
52 // Update density estimate.
53 constexpr float kWidth = 0.01f;
54 constexpr float kOneByWidthPlus2 = 1.f / (2.f * kWidth);
55 if (fabs(log_spectrum[i] - log_quantile_[j]) < kWidth) {
56 density_[j] = (counter_[s] * density_[j] + kOneByWidthPlus2) *
57 one_by_counter_plus_1;
58 }
59 }
60
61 if (counter_[s] >= kLongStartupPhaseBlocks) {
62 counter_[s] = 0;
63 if (num_updates_ >= kLongStartupPhaseBlocks) {
64 quantile_index_to_return = k;
65 }
66 }
67
68 ++counter_[s];
69 }
70
71 // Sequentially update the noise during startup.
72 if (num_updates_ < kLongStartupPhaseBlocks) {
73 // Use the last "s" to get noise during startup that differ from zero.
74 quantile_index_to_return = kFftSizeBy2Plus1 * (kSimult - 1);
75 ++num_updates_;
76 }
77
78 if (quantile_index_to_return >= 0) {
79 ExpApproximation(
80 rtc::ArrayView<const float>(&log_quantile_[quantile_index_to_return],
81 kFftSizeBy2Plus1),
82 quantile_);
83 }
84
85 std::copy(quantile_.begin(), quantile_.end(), noise_spectrum.begin());
86 }
87
88 } // namespace webrtc
89