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/*
* Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef MODULES_AUDIO_PROCESSING_VAD_GMM_H_
#define MODULES_AUDIO_PROCESSING_VAD_GMM_H_
namespace webrtc {
// A structure that specifies a GMM.
// A GMM is formulated as
// f(x) = w[0] * mixture[0] + w[1] * mixture[1] + ... +
// w[num_mixtures - 1] * mixture[num_mixtures - 1];
// Where a 'mixture' is a Gaussian density.
struct GmmParameters {
// weight[n] = log(w[n]) - `dimension`/2 * log(2*pi) - 1/2 * log(det(cov[n]));
// where cov[n] is the covariance matrix of mixture n;
const double* weight;
// pointer to the first element of a `num_mixtures`x`dimension` matrix
// where kth row is the mean of the kth mixture.
const double* mean;
// pointer to the first element of a `num_mixtures`x`dimension`x`dimension`
// 3D-matrix, where the kth 2D-matrix is the inverse of the covariance
// matrix of the kth mixture.
const double* covar_inverse;
// Dimensionality of the mixtures.
int dimension;
// number of the mixtures.
int num_mixtures;
};
// Evaluate the given GMM, according to `gmm_parameters`, at the given point
// `x`. If the dimensionality of the given GMM is larger that the maximum
// acceptable dimension by the following function -1 is returned.
double EvaluateGmm(const double* x, const GmmParameters& gmm_parameters);
} // namespace webrtc
#endif // MODULES_AUDIO_PROCESSING_VAD_GMM_H_
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