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 #include <stdlib.h>
15
16 #include "typedefs.h" // NOLINT(build/include)
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