1 /*
2 * Copyright (c) 2014 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 #define _USE_MATH_DEFINES
12
13 #include "webrtc/modules/audio_processing/beamformer/covariance_matrix_generator.h"
14
15 #include <cmath>
16
17 namespace webrtc {
18 namespace {
19
BesselJ0(float x)20 float BesselJ0(float x) {
21 #if WEBRTC_WIN
22 return _j0(x);
23 #else
24 return j0(x);
25 #endif
26 }
27
28 // Calculates the Euclidean norm for a row vector.
Norm(const ComplexMatrix<float> & x)29 float Norm(const ComplexMatrix<float>& x) {
30 RTC_CHECK_EQ(1, x.num_rows());
31 const size_t length = x.num_columns();
32 const complex<float>* elems = x.elements()[0];
33 float result = 0.f;
34 for (size_t i = 0u; i < length; ++i) {
35 result += std::norm(elems[i]);
36 }
37 return std::sqrt(result);
38 }
39
40 } // namespace
41
UniformCovarianceMatrix(float wave_number,const std::vector<Point> & geometry,ComplexMatrix<float> * mat)42 void CovarianceMatrixGenerator::UniformCovarianceMatrix(
43 float wave_number,
44 const std::vector<Point>& geometry,
45 ComplexMatrix<float>* mat) {
46 RTC_CHECK_EQ(static_cast<int>(geometry.size()), mat->num_rows());
47 RTC_CHECK_EQ(static_cast<int>(geometry.size()), mat->num_columns());
48
49 complex<float>* const* mat_els = mat->elements();
50 for (size_t i = 0; i < geometry.size(); ++i) {
51 for (size_t j = 0; j < geometry.size(); ++j) {
52 if (wave_number > 0.f) {
53 mat_els[i][j] =
54 BesselJ0(wave_number * Distance(geometry[i], geometry[j]));
55 } else {
56 mat_els[i][j] = i == j ? 1.f : 0.f;
57 }
58 }
59 }
60 }
61
AngledCovarianceMatrix(float sound_speed,float angle,size_t frequency_bin,size_t fft_size,size_t num_freq_bins,int sample_rate,const std::vector<Point> & geometry,ComplexMatrix<float> * mat)62 void CovarianceMatrixGenerator::AngledCovarianceMatrix(
63 float sound_speed,
64 float angle,
65 size_t frequency_bin,
66 size_t fft_size,
67 size_t num_freq_bins,
68 int sample_rate,
69 const std::vector<Point>& geometry,
70 ComplexMatrix<float>* mat) {
71 RTC_CHECK_EQ(static_cast<int>(geometry.size()), mat->num_rows());
72 RTC_CHECK_EQ(static_cast<int>(geometry.size()), mat->num_columns());
73
74 ComplexMatrix<float> interf_cov_vector(1, geometry.size());
75 ComplexMatrix<float> interf_cov_vector_transposed(geometry.size(), 1);
76 PhaseAlignmentMasks(frequency_bin,
77 fft_size,
78 sample_rate,
79 sound_speed,
80 geometry,
81 angle,
82 &interf_cov_vector);
83 interf_cov_vector.Scale(1.f / Norm(interf_cov_vector));
84 interf_cov_vector_transposed.Transpose(interf_cov_vector);
85 interf_cov_vector.PointwiseConjugate();
86 mat->Multiply(interf_cov_vector_transposed, interf_cov_vector);
87 }
88
PhaseAlignmentMasks(size_t frequency_bin,size_t fft_size,int sample_rate,float sound_speed,const std::vector<Point> & geometry,float angle,ComplexMatrix<float> * mat)89 void CovarianceMatrixGenerator::PhaseAlignmentMasks(
90 size_t frequency_bin,
91 size_t fft_size,
92 int sample_rate,
93 float sound_speed,
94 const std::vector<Point>& geometry,
95 float angle,
96 ComplexMatrix<float>* mat) {
97 RTC_CHECK_EQ(1, mat->num_rows());
98 RTC_CHECK_EQ(static_cast<int>(geometry.size()), mat->num_columns());
99
100 float freq_in_hertz =
101 (static_cast<float>(frequency_bin) / fft_size) * sample_rate;
102
103 complex<float>* const* mat_els = mat->elements();
104 for (size_t c_ix = 0; c_ix < geometry.size(); ++c_ix) {
105 float distance = std::cos(angle) * geometry[c_ix].x() +
106 std::sin(angle) * geometry[c_ix].y();
107 float phase_shift = -2.f * M_PI * distance * freq_in_hertz / sound_speed;
108
109 // Euler's formula for mat[0][c_ix] = e^(j * phase_shift).
110 mat_els[0][c_ix] = complex<float>(cos(phase_shift), sin(phase_shift));
111 }
112 }
113
114 } // namespace webrtc
115