1 /*
2 * Copyright (c) 2017 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/aec3/erl_estimator.h"
12
13 #include <algorithm>
14 #include <numeric>
15
16 namespace webrtc {
17
18 namespace {
19
20 constexpr float kMinErl = 0.01f;
21 constexpr float kMaxErl = 1000.f;
22
23 } // namespace
24
ErlEstimator()25 ErlEstimator::ErlEstimator() {
26 erl_.fill(kMaxErl);
27 hold_counters_.fill(0);
28 erl_time_domain_ = kMaxErl;
29 hold_counter_time_domain_ = 0;
30 }
31
32 ErlEstimator::~ErlEstimator() = default;
33
Update(const std::array<float,kFftLengthBy2Plus1> & render_spectrum,const std::array<float,kFftLengthBy2Plus1> & capture_spectrum)34 void ErlEstimator::Update(
35 const std::array<float, kFftLengthBy2Plus1>& render_spectrum,
36 const std::array<float, kFftLengthBy2Plus1>& capture_spectrum) {
37 const auto& X2 = render_spectrum;
38 const auto& Y2 = capture_spectrum;
39
40 // Corresponds to WGN of power -46 dBFS.
41 constexpr float kX2Min = 44015068.0f;
42
43 // Update the estimates in a maximum statistics manner.
44 for (size_t k = 1; k < kFftLengthBy2; ++k) {
45 if (X2[k] > kX2Min) {
46 const float new_erl = Y2[k] / X2[k];
47 if (new_erl < erl_[k]) {
48 hold_counters_[k - 1] = 1000;
49 erl_[k] += 0.1f * (new_erl - erl_[k]);
50 erl_[k] = std::max(erl_[k], kMinErl);
51 }
52 }
53 }
54
55 std::for_each(hold_counters_.begin(), hold_counters_.end(),
56 [](int& a) { --a; });
57 std::transform(hold_counters_.begin(), hold_counters_.end(), erl_.begin() + 1,
58 erl_.begin() + 1, [](int a, float b) {
59 return a > 0 ? b : std::min(kMaxErl, 2.f * b);
60 });
61
62 erl_[0] = erl_[1];
63 erl_[kFftLengthBy2] = erl_[kFftLengthBy2 - 1];
64
65 // Compute ERL over all frequency bins.
66 const float X2_sum = std::accumulate(X2.begin(), X2.end(), 0.0f);
67
68 if (X2_sum > kX2Min * X2.size()) {
69 const float Y2_sum = std::accumulate(Y2.begin(), Y2.end(), 0.0f);
70 const float new_erl = Y2_sum / X2_sum;
71 if (new_erl < erl_time_domain_) {
72 hold_counter_time_domain_ = 1000;
73 erl_time_domain_ += 0.1f * (new_erl - erl_time_domain_);
74 erl_time_domain_ = std::max(erl_time_domain_, kMinErl);
75 }
76 }
77
78 --hold_counter_time_domain_;
79 erl_time_domain_ = (hold_counter_time_domain_ > 0)
80 ? erl_time_domain_
81 : std::min(kMaxErl, 2.f * erl_time_domain_);
82 }
83
84 } // namespace webrtc
85