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 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 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 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
