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