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#ifndef WEBRTC_MODULES_AUDIO_PROCESSING_VAD_GMM_H_
12#define WEBRTC_MODULES_AUDIO_PROCESSING_VAD_GMM_H_
13
14namespace webrtc {
15
16// A structure that specifies a GMM.
17// A GMM is formulated as
18//  f(x) = w[0] * mixture[0] + w[1] * mixture[1] + ... +
19//         w[num_mixtures - 1] * mixture[num_mixtures - 1];
20// Where a 'mixture' is a Gaussian density.
21
22struct GmmParameters {
23  // weight[n] = log(w[n]) - |dimension|/2 * log(2*pi) - 1/2 * log(det(cov[n]));
24  // where cov[n] is the covariance matrix of mixture n;
25  const double* weight;
26  // pointer to the first element of a |num_mixtures|x|dimension| matrix
27  // where kth row is the mean of the kth mixture.
28  const double* mean;
29  // pointer to the first element of a |num_mixtures|x|dimension|x|dimension|
30  // 3D-matrix, where the kth 2D-matrix is the inverse of the covariance
31  // matrix of the kth mixture.
32  const double* covar_inverse;
33  // Dimensionality of the mixtures.
34  int dimension;
35  // number of the mixtures.
36  int num_mixtures;
37};
38
39// Evaluate the given GMM, according to |gmm_parameters|, at the given point
40// |x|. If the dimensionality of the given GMM is larger that the maximum
41// acceptable dimension by the following function -1 is returned.
42double EvaluateGmm(const double* x, const GmmParameters& gmm_parameters);
43
44}  // namespace webrtc
45#endif  // WEBRTC_MODULES_AUDIO_PROCESSING_VAD_GMM_H_
46