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 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. 29 float Norm(const ComplexMatrix<float>& x) { 30 RTC_CHECK_EQ(1u, 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 42 void CovarianceMatrixGenerator::UniformCovarianceMatrix( 43 float wave_number, 44 const std::vector<Point>& geometry, 45 ComplexMatrix<float>* mat) { 46 RTC_CHECK_EQ(geometry.size(), mat->num_rows()); 47 RTC_CHECK_EQ(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 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(geometry.size(), mat->num_rows()); 72 RTC_CHECK_EQ(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 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(1u, mat->num_rows()); 98 RTC_CHECK_EQ(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
