62 lines
1.8 KiB
C++
62 lines
1.8 KiB
C++
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/*
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* Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "modules/audio_processing/vad/gmm.h"
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#include <math.h>
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namespace webrtc {
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static const int kMaxDimension = 10;
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static void RemoveMean(const double* in,
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const double* mean_vec,
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int dimension,
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double* out) {
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for (int n = 0; n < dimension; ++n)
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out[n] = in[n] - mean_vec[n];
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}
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static double ComputeExponent(const double* in,
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const double* covar_inv,
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int dimension) {
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double q = 0;
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for (int i = 0; i < dimension; ++i) {
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double v = 0;
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for (int j = 0; j < dimension; j++)
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v += (*covar_inv++) * in[j];
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q += v * in[i];
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}
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q *= -0.5;
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return q;
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}
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double EvaluateGmm(const double* x, const GmmParameters& gmm_parameters) {
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if (gmm_parameters.dimension > kMaxDimension) {
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return -1; // This is invalid pdf so the caller can check this.
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}
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double f = 0;
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double v[kMaxDimension];
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const double* mean_vec = gmm_parameters.mean;
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const double* covar_inv = gmm_parameters.covar_inverse;
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for (int n = 0; n < gmm_parameters.num_mixtures; n++) {
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RemoveMean(x, mean_vec, gmm_parameters.dimension, v);
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double q = ComputeExponent(v, covar_inv, gmm_parameters.dimension) +
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gmm_parameters.weight[n];
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f += exp(q);
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mean_vec += gmm_parameters.dimension;
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covar_inv += gmm_parameters.dimension * gmm_parameters.dimension;
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}
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return f;
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}
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} // namespace webrtc
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