Pull the Voice Activity Detector out from the AGC

webrtc/modules/audio_processing/agc/gmm.h

-/*
- *  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 WEBRTC_MODULES_AUDIO_PROCESSING_AGC_GMM_H_
-#define WEBRTC_MODULES_AUDIO_PROCESSING_AGC_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  // WEBRTC_MODULES_AUDIO_PROCESSING_AGC_GMM_H_