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/suppression_filter.h"
12
13 #include <math.h>
14 #include <algorithm>
15 #include <cstring>
16 #include <functional>
17 #include <numeric>
18
19 #include "modules/audio_processing/utility/ooura_fft.h"
20 #include "rtc_base/numerics/safe_minmax.h"
21
22 namespace webrtc {
23 namespace {
24
25 // Hanning window from Matlab command win = sqrt(hanning(128)).
26 const float kSqrtHanning[kFftLength] = {
27 0.00000000000000f, 0.02454122852291f, 0.04906767432742f, 0.07356456359967f,
28 0.09801714032956f, 0.12241067519922f, 0.14673047445536f, 0.17096188876030f,
29 0.19509032201613f, 0.21910124015687f, 0.24298017990326f, 0.26671275747490f,
30 0.29028467725446f, 0.31368174039889f, 0.33688985339222f, 0.35989503653499f,
31 0.38268343236509f, 0.40524131400499f, 0.42755509343028f, 0.44961132965461f,
32 0.47139673682600f, 0.49289819222978f, 0.51410274419322f, 0.53499761988710f,
33 0.55557023301960f, 0.57580819141785f, 0.59569930449243f, 0.61523159058063f,
34 0.63439328416365f, 0.65317284295378f, 0.67155895484702f, 0.68954054473707f,
35 0.70710678118655f, 0.72424708295147f, 0.74095112535496f, 0.75720884650648f,
36 0.77301045336274f, 0.78834642762661f, 0.80320753148064f, 0.81758481315158f,
37 0.83146961230255f, 0.84485356524971f, 0.85772861000027f, 0.87008699110871f,
38 0.88192126434835f, 0.89322430119552f, 0.90398929312344f, 0.91420975570353f,
39 0.92387953251129f, 0.93299279883474f, 0.94154406518302f, 0.94952818059304f,
40 0.95694033573221f, 0.96377606579544f, 0.97003125319454f, 0.97570213003853f,
41 0.98078528040323f, 0.98527764238894f, 0.98917650996478f, 0.99247953459871f,
42 0.99518472667220f, 0.99729045667869f, 0.99879545620517f, 0.99969881869620f,
43 1.00000000000000f, 0.99969881869620f, 0.99879545620517f, 0.99729045667869f,
44 0.99518472667220f, 0.99247953459871f, 0.98917650996478f, 0.98527764238894f,
45 0.98078528040323f, 0.97570213003853f, 0.97003125319454f, 0.96377606579544f,
46 0.95694033573221f, 0.94952818059304f, 0.94154406518302f, 0.93299279883474f,
47 0.92387953251129f, 0.91420975570353f, 0.90398929312344f, 0.89322430119552f,
48 0.88192126434835f, 0.87008699110871f, 0.85772861000027f, 0.84485356524971f,
49 0.83146961230255f, 0.81758481315158f, 0.80320753148064f, 0.78834642762661f,
50 0.77301045336274f, 0.75720884650648f, 0.74095112535496f, 0.72424708295147f,
51 0.70710678118655f, 0.68954054473707f, 0.67155895484702f, 0.65317284295378f,
52 0.63439328416365f, 0.61523159058063f, 0.59569930449243f, 0.57580819141785f,
53 0.55557023301960f, 0.53499761988710f, 0.51410274419322f, 0.49289819222978f,
54 0.47139673682600f, 0.44961132965461f, 0.42755509343028f, 0.40524131400499f,
55 0.38268343236509f, 0.35989503653499f, 0.33688985339222f, 0.31368174039889f,
56 0.29028467725446f, 0.26671275747490f, 0.24298017990326f, 0.21910124015687f,
57 0.19509032201613f, 0.17096188876030f, 0.14673047445536f, 0.12241067519922f,
58 0.09801714032956f, 0.07356456359967f, 0.04906767432742f, 0.02454122852291f};
59
60 } // namespace
61
SuppressionFilter(int sample_rate_hz)62 SuppressionFilter::SuppressionFilter(int sample_rate_hz)
63 : sample_rate_hz_(sample_rate_hz),
64 fft_(),
65 e_output_old_(NumBandsForRate(sample_rate_hz_)) {
66 RTC_DCHECK(ValidFullBandRate(sample_rate_hz_));
67 e_input_old_.fill(0.f);
68 std::for_each(e_output_old_.begin(), e_output_old_.end(),
69 [](std::array<float, kFftLengthBy2>& a) { a.fill(0.f); });
70 }
71
72 SuppressionFilter::~SuppressionFilter() = default;
73
ApplyGain(const FftData & comfort_noise,const FftData & comfort_noise_high_band,const std::array<float,kFftLengthBy2Plus1> & suppression_gain,float high_bands_gain,std::vector<std::vector<float>> * e)74 void SuppressionFilter::ApplyGain(
75 const FftData& comfort_noise,
76 const FftData& comfort_noise_high_band,
77 const std::array<float, kFftLengthBy2Plus1>& suppression_gain,
78 float high_bands_gain,
79 std::vector<std::vector<float>>* e) {
80 RTC_DCHECK(e);
81 RTC_DCHECK_EQ(e->size(), NumBandsForRate(sample_rate_hz_));
82 FftData E;
83 std::array<float, kFftLength> e_extended;
84 constexpr float kIfftNormalization = 2.f / kFftLength;
85
86 // Analysis filterbank.
87 std::transform(e_input_old_.begin(), e_input_old_.end(),
88 std::begin(kSqrtHanning), e_extended.begin(),
89 std::multiplies<float>());
90 std::transform((*e)[0].begin(), (*e)[0].end(),
91 std::begin(kSqrtHanning) + kFftLengthBy2,
92 e_extended.begin() + kFftLengthBy2, std::multiplies<float>());
93 std::copy((*e)[0].begin(), (*e)[0].end(), e_input_old_.begin());
94 fft_.Fft(&e_extended, &E);
95
96 // Apply gain.
97 std::transform(suppression_gain.begin(), suppression_gain.end(), E.re.begin(),
98 E.re.begin(), std::multiplies<float>());
99 std::transform(suppression_gain.begin(), suppression_gain.end(), E.im.begin(),
100 E.im.begin(), std::multiplies<float>());
101
102 // Compute and add the comfort noise.
103 std::array<float, kFftLengthBy2Plus1> scaled_comfort_noise;
104 std::transform(suppression_gain.begin(), suppression_gain.end(),
105 comfort_noise.re.begin(), scaled_comfort_noise.begin(),
106 [](float a, float b) { return std::max(1.f - a, 0.f) * b; });
107 std::transform(scaled_comfort_noise.begin(), scaled_comfort_noise.end(),
108 E.re.begin(), E.re.begin(), std::plus<float>());
109 std::transform(suppression_gain.begin(), suppression_gain.end(),
110 comfort_noise.im.begin(), scaled_comfort_noise.begin(),
111 [](float a, float b) { return std::max(1.f - a, 0.f) * b; });
112 std::transform(scaled_comfort_noise.begin(), scaled_comfort_noise.end(),
113 E.im.begin(), E.im.begin(), std::plus<float>());
114
115 // Synthesis filterbank.
116 fft_.Ifft(E, &e_extended);
117 std::transform(e_output_old_[0].begin(), e_output_old_[0].end(),
118 std::begin(kSqrtHanning) + kFftLengthBy2, (*e)[0].begin(),
119 [&](float a, float b) { return kIfftNormalization * a * b; });
120 std::transform(e_extended.begin(), e_extended.begin() + kFftLengthBy2,
121 std::begin(kSqrtHanning), e_extended.begin(),
122 [&](float a, float b) { return kIfftNormalization * a * b; });
123 std::transform((*e)[0].begin(), (*e)[0].end(), e_extended.begin(),
124 (*e)[0].begin(), std::plus<float>());
125 std::for_each((*e)[0].begin(), (*e)[0].end(), [](float& x_k) {
126 x_k = rtc::SafeClamp(x_k, -32768.f, 32767.f);
127 });
128 std::copy(e_extended.begin() + kFftLengthBy2, e_extended.begin() + kFftLength,
129 std::begin(e_output_old_[0]));
130
131 if (e->size() > 1) {
132 // Form time-domain high-band noise.
133 std::array<float, kFftLength> time_domain_high_band_noise;
134 std::transform(comfort_noise_high_band.re.begin(),
135 comfort_noise_high_band.re.end(), E.re.begin(),
136 [&](float a) { return kIfftNormalization * a; });
137 std::transform(comfort_noise_high_band.im.begin(),
138 comfort_noise_high_band.im.end(), E.im.begin(),
139 [&](float a) { return kIfftNormalization * a; });
140 fft_.Ifft(E, &time_domain_high_band_noise);
141
142 // Scale and apply the noise to the signals.
143 const float high_bands_noise_scaling =
144 0.4f * std::max(1.f - high_bands_gain, 0.f);
145
146 std::transform(
147 (*e)[1].begin(), (*e)[1].end(), time_domain_high_band_noise.begin(),
148 (*e)[1].begin(), [&](float a, float b) {
149 return std::max(
150 std::min(b * high_bands_noise_scaling + high_bands_gain * a,
151 32767.0f),
152 -32768.0f);
153 });
154
155 if (e->size() > 2) {
156 RTC_DCHECK_EQ(3, e->size());
157 std::for_each((*e)[2].begin(), (*e)[2].end(), [&](float& a) {
158 a = rtc::SafeClamp(a * high_bands_gain, -32768.f, 32767.f);
159 });
160 }
161
162 std::array<float, kFftLengthBy2> tmp;
163 for (size_t k = 1; k < e->size(); ++k) {
164 std::copy((*e)[k].begin(), (*e)[k].end(), tmp.begin());
165 std::copy(e_output_old_[k].begin(), e_output_old_[k].end(),
166 (*e)[k].begin());
167 std::copy(tmp.begin(), tmp.end(), e_output_old_[k].begin());
168 }
169 }
170 }
171
172 } // namespace webrtc
173