gmm.cc (1876B)
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 <cmath> 14 15 namespace webrtc { 16 17 static const int kMaxDimension = 10; 18 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 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 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