Implement new version of the NonlinearBeamformer

webrtc/modules/audio_processing/beamformer/covariance_matrix_generator.cc

 /*
  *  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 <cmath>
 
+namespace webrtc {
 namespace {
 
 float BesselJ0(float x) {
 #if WEBRTC_WIN
   return _j0(x);
 #else
   return j0(x);
 #endif
 }
 
+float norm(const ComplexMatrix<float>& x) {

[Andrew MacDonald, 2015/10/06 23:54:31]

Norm

Add a comment clarifying what it computes.

This is only used at create-time, right? I ask because std::abs can be slow on
complex values, see cr/101731720.

[aluebs-webrtc, 2015/10/07 22:08:05]

Changed naming and added documentation.
Yes, it only is used at create-time, but will be used every time we steer the
beam on the future. But we want to minimize this anyway, and it only is called 2
times (for each scenario) and then one time for each mic.

+  RTC_CHECK_EQ(1, x.num_rows());
+  size_t length = x.num_columns();

[Andrew MacDonald, 2015/10/06 23:54:31]

const

[aluebs-webrtc, 2015/10/07 22:08:05]

Done.

+  const complex<float>* elems = x.elements()[0];
+  float result = 0.f;
+  for (size_t i = 0u; i < length; ++i) {
+    result += std::abs(elems[i]) * std::abs(elems[i]);

[Andrew MacDonald, 2015/10/06 23:54:31]

Don't compute std::abs twice. Looks like what you want is std::norm.

[aluebs-webrtc, 2015/10/07 22:08:05]

Good point. Done.

+  }
+  return std::sqrt(result);
+}
+
 }  // namespace
 
-namespace webrtc {
-
 void CovarianceMatrixGenerator::UniformCovarianceMatrix(
     float wave_number,
     const std::vector<Point>& geometry,
     ComplexMatrix<float>* mat) {
   RTC_CHECK_EQ(static_cast<int>(geometry.size()), mat->num_rows());
   RTC_CHECK_EQ(static_cast<int>(geometry.size()), mat->num_columns());
 
   complex<float>* const* mat_els = mat->elements();
   for (size_t i = 0; i < geometry.size(); ++i) {
     for (size_t j = 0; j < geometry.size(); ++j) {
@@ skipping 21 matching lines @@
 
   ComplexMatrix<float> interf_cov_vector(1, geometry.size());
   ComplexMatrix<float> interf_cov_vector_transposed(geometry.size(), 1);
   PhaseAlignmentMasks(frequency_bin,
                       fft_size,
                       sample_rate,
                       sound_speed,
                       geometry,
                       angle,
                       &interf_cov_vector);
+  complex<float> norm_factor = norm(interf_cov_vector);
+  interf_cov_vector.Scale(1.f / norm_factor);
   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,
@@ skipping 11 matching lines @@
     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<float>(cos(phase_shift), sin(phase_shift));
   }
 }
 
 }  // namespace webrtc