Line data    Source code

       1             : /*
       2             :  *  Copyright (c) 2012 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             : #include "webrtc/modules/audio_processing/vad/gmm.h"
      12             : 
      13             : #include <math.h>
      14             : #include <stdlib.h>
      15             : 
      16             : #include "webrtc/typedefs.h"
      17             : 
      18             : namespace webrtc {
      19             : 
      20             : static const int kMaxDimension = 10;
      21             : 
      22           0 : static void RemoveMean(const double* in,
      23             :                        const double* mean_vec,
      24             :                        int dimension,
      25             :                        double* out) {
      26           0 :   for (int n = 0; n < dimension; ++n)
      27           0 :     out[n] = in[n] - mean_vec[n];
      28           0 : }
      29             : 
      30           0 : static double ComputeExponent(const double* in,
      31             :                               const double* covar_inv,
      32             :                               int dimension) {
      33           0 :   double q = 0;
      34           0 :   for (int i = 0; i < dimension; ++i) {
      35           0 :     double v = 0;
      36           0 :     for (int j = 0; j < dimension; j++)
      37           0 :       v += (*covar_inv++) * in[j];
      38           0 :     q += v * in[i];
      39             :   }
      40           0 :   q *= -0.5;
      41           0 :   return q;
      42             : }
      43             : 
      44           0 : double EvaluateGmm(const double* x, const GmmParameters& gmm_parameters) {
      45           0 :   if (gmm_parameters.dimension > kMaxDimension) {
      46           0 :     return -1;  // This is invalid pdf so the caller can check this.
      47             :   }
      48           0 :   double f = 0;
      49             :   double v[kMaxDimension];
      50           0 :   const double* mean_vec = gmm_parameters.mean;
      51           0 :   const double* covar_inv = gmm_parameters.covar_inverse;
      52             : 
      53           0 :   for (int n = 0; n < gmm_parameters.num_mixtures; n++) {
      54           0 :     RemoveMean(x, mean_vec, gmm_parameters.dimension, v);
      55           0 :     double q = ComputeExponent(v, covar_inv, gmm_parameters.dimension) +
      56           0 :                gmm_parameters.weight[n];
      57           0 :     f += exp(q);
      58           0 :     mean_vec += gmm_parameters.dimension;
      59           0 :     covar_inv += gmm_parameters.dimension * gmm_parameters.dimension;
      60             :   }
      61           0 :   return f;
      62             : }
      63             : 
      64             : }  // namespace webrtc