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 /* * Copyright (c) 2014 The WebRTC project authors. All Rights Reserved. * * Use of this source code is governed by a BSD-style license * that can be found in the LICENSE file in the root of the source * tree. An additional intellectual property rights grant can be found * in the file PATENTS. All contributing project authors may * be found in the AUTHORS file in the root of the source tree. */ #define _USE_MATH_DEFINES #include "webrtc/modules/audio_processing/beamformer/covariance_matrix_generator.h" #include namespace webrtc { namespace { float BesselJ0(float x) { #ifdef WEBRTC_WIN return _j0(x); #else return j0(x); #endif } // Calculates the Euclidean norm for a row vector. float Norm(const ComplexMatrix& x) { RTC_CHECK_EQ(1, x.num_rows()); const size_t length = x.num_columns(); const complex* elems = x.elements()[0]; float result = 0.f; for (size_t i = 0u; i < length; ++i) { result += std::norm(elems[i]); } return std::sqrt(result); } } // namespace void CovarianceMatrixGenerator::UniformCovarianceMatrix( float wave_number, const std::vector& geometry, ComplexMatrix* mat) { RTC_CHECK_EQ(geometry.size(), mat->num_rows()); RTC_CHECK_EQ(geometry.size(), mat->num_columns()); complex* const* mat_els = mat->elements(); for (size_t i = 0; i < geometry.size(); ++i) { for (size_t j = 0; j < geometry.size(); ++j) { if (wave_number > 0.f) { mat_els[i][j] = BesselJ0(wave_number * Distance(geometry[i], geometry[j])); } else { mat_els[i][j] = i == j ? 1.f : 0.f; } } } } void CovarianceMatrixGenerator::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& geometry, ComplexMatrix* mat) { RTC_CHECK_EQ(geometry.size(), mat->num_rows()); RTC_CHECK_EQ(geometry.size(), mat->num_columns()); ComplexMatrix interf_cov_vector(1, geometry.size()); ComplexMatrix interf_cov_vector_transposed(geometry.size(), 1); PhaseAlignmentMasks(frequency_bin, fft_size, sample_rate, sound_speed, geometry, angle, &interf_cov_vector); interf_cov_vector.Scale(1.f / Norm(interf_cov_vector)); interf_cov_vector_transposed.Transpose(interf_cov_vector); interf_cov_vector.PointwiseConjugate(); mat->Multiply(interf_cov_vector_transposed, interf_cov_vector); } void CovarianceMatrixGenerator::PhaseAlignmentMasks( size_t frequency_bin, size_t fft_size, int sample_rate, float sound_speed, const std::vector& geometry, float angle, ComplexMatrix* mat) { RTC_CHECK_EQ(1, mat->num_rows()); RTC_CHECK_EQ(geometry.size(), mat->num_columns()); float freq_in_hertz = (static_cast(frequency_bin) / fft_size) * sample_rate; complex* const* mat_els = mat->elements(); for (size_t c_ix = 0; c_ix < geometry.size(); ++c_ix) { float distance = std::cos(angle) * geometry[c_ix].x() + std::sin(angle) * geometry[c_ix].y(); float phase_shift = -2.f * M_PI * distance * freq_in_hertz / sound_speed; // Euler's formula for mat[0][c_ix] = e^(j * phase_shift). mat_els[0][c_ix] = complex(cos(phase_shift), sin(phase_shift)); } } } // namespace webrtc