2 Copyright (C) 2007-2009 Paul Brossier <piem@aubio.org>
3 and Amaury Hazan <ahazan@iua.upf.edu>
5 This file is part of aubio.
7 aubio is free software: you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation, either version 3 of the License, or
10 (at your option) any later version.
12 aubio is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with aubio. If not, see <http://www.gnu.org/licenses/>.
22 #include "aubio_priv.h"
25 #include "spectral/fft.h"
26 #include "spectral/filterbank_mel.h"
27 #include "spectral/mfcc.h"
29 /** Internal structure for mfcc object */
33 uint_t win_s; /** grain length */
34 uint_t samplerate; /** sample rate (needed?) */
35 uint_t n_filters; /** number of *filters */
36 uint_t n_coefs; /** number of coefficients (<= n_filters/2 +1) */
37 aubio_filterbank_t *fb; /** filter bank */
38 fvec_t *in_dct; /** input buffer for dct * [fb->n_filters] */
39 fvec_t *dct_coeffs; /** DCT transform n_filters * n_coeffs */
44 new_aubio_mfcc (uint_t win_s, uint_t samplerate, uint_t n_filters,
48 /* allocate space for mfcc object */
49 aubio_mfcc_t *mfcc = AUBIO_NEW (aubio_mfcc_t);
54 mfcc->samplerate = samplerate;
55 mfcc->n_filters = n_filters;
56 mfcc->n_coefs = n_coefs;
58 /* filterbank allocation */
59 mfcc->fb = new_aubio_filterbank (n_filters, mfcc->win_s);
60 aubio_filterbank_set_mel_coeffs_slaney (mfcc->fb, samplerate);
62 /* allocating buffers */
63 mfcc->in_dct = new_fvec (n_filters, 1);
65 mfcc->dct_coeffs = new_fvec (n_coefs, n_filters);
67 /* compute DCT transform dct_coeffs[i][j] as
68 cos ( j * (i+.5) * PI / n_filters ) */
69 smpl_t scaling = 1. / SQRT (n_filters / 2.);
70 for (i = 0; i < n_filters; i++) {
71 for (j = 0; j < n_coefs; j++) {
72 mfcc->dct_coeffs->data[i][j] =
73 scaling * COS (j * (i + 0.5) * PI / n_filters);
75 mfcc->dct_coeffs->data[i][0] *= SQRT (2.) / 2.;
82 del_aubio_mfcc (aubio_mfcc_t * mf)
85 /* delete filterbank */
86 del_aubio_filterbank (mf->fb);
89 del_fvec (mf->in_dct);
91 /* delete mfcc object */
97 aubio_mfcc_do (aubio_mfcc_t * mf, cvec_t * in, fvec_t * out)
101 /* compute filterbank */
102 aubio_filterbank_do (mf->fb, in, mf->in_dct);
107 /* compute discrete cosine transform */
108 for (i = 0; i < mf->n_filters; i++) {
109 for (j = 0; j < mf->n_coefs; j++) {
110 out->data[0][j] += mf->in_dct->data[0][i]
111 * mf->dct_coeffs->data[i][j];