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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 
RemoveMean(const double * in,const double * mean_vec,int dimension,double * out)22 static void RemoveMean(const double* in,
23                        const double* mean_vec,
24                        int dimension,
25                        double* out) {
26   for (int n = 0; n < dimension; ++n)
27     out[n] = in[n] - mean_vec[n];
28 }
29 
ComputeExponent(const double * in,const double * covar_inv,int dimension)30 static double ComputeExponent(const double* in,
31                               const double* covar_inv,
32                               int dimension) {
33   double q = 0;
34   for (int i = 0; i < dimension; ++i) {
35     double v = 0;
36     for (int j = 0; j < dimension; j++)
37       v += (*covar_inv++) * in[j];
38     q += v * in[i];
39   }
40   q *= -0.5;
41   return q;
42 }
43 
EvaluateGmm(const double * x,const GmmParameters & gmm_parameters)44 double EvaluateGmm(const double* x, const GmmParameters& gmm_parameters) {
45   if (gmm_parameters.dimension > kMaxDimension) {
46     return -1;  // This is invalid pdf so the caller can check this.
47   }
48   double f = 0;
49   double v[kMaxDimension];
50   const double* mean_vec = gmm_parameters.mean;
51   const double* covar_inv = gmm_parameters.covar_inverse;
52 
53   for (int n = 0; n < gmm_parameters.num_mixtures; n++) {
54     RemoveMean(x, mean_vec, gmm_parameters.dimension, v);
55     double q = ComputeExponent(v, covar_inv, gmm_parameters.dimension) +
56                gmm_parameters.weight[n];
57     f += exp(q);
58     mean_vec += gmm_parameters.dimension;
59     covar_inv += gmm_parameters.dimension * gmm_parameters.dimension;
60   }
61   return f;
62 }
63 
64 }  // namespace webrtc
65