Implement new version of the NonlinearBeamformer

webrtc/modules/audio_processing/beamformer/covariance_matrix_generator.cc

Index: webrtc/modules/audio_processing/beamformer/covariance_matrix_generator.cc
diff --git a/webrtc/modules/audio_processing/beamformer/covariance_matrix_generator.cc b/webrtc/modules/audio_processing/beamformer/covariance_matrix_generator.cc
index efc5b0f71afd5b04782bd238e26bc78784d38da0..34a08650e1ead1aa20147c9fc17c6f2a80fe14c1 100644
--- a/webrtc/modules/audio_processing/beamformer/covariance_matrix_generator.cc
+++ b/webrtc/modules/audio_processing/beamformer/covariance_matrix_generator.cc
@@ -14,6 +14,7 @@
 
 #include <cmath>
 
+namespace webrtc {
 namespace {
 
 float BesselJ0(float x) {
@@ -24,9 +25,18 @@ float BesselJ0(float x) {
 #endif
 }
 
-}  // namespace
+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 webrtc {
+}  // namespace
 
 void CovarianceMatrixGenerator::UniformCovarianceMatrix(
     float wave_number,
@@ -69,6 +79,8 @@ void CovarianceMatrixGenerator::AngledCovarianceMatrix(
                       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);