source: src/spectral/mfcc.c @ 7a84b21

feature/autosinkfeature/cnnfeature/cnn_orgfeature/constantqfeature/crepefeature/crepe_orgfeature/pitchshiftfeature/pydocstringsfeature/timestretchfix/ffmpeg5pitchshiftsamplertimestretchyinfft+
Last change on this file since 7a84b21 was 7a84b21, checked in by Paul Brossier <piem@piem.org>, 15 years ago

src/spectral/mfcc.c: indent, update to GPLv3

  • Property mode set to 100644
File size: 2.9 KB
Line 
1/*
2  Copyright (C) 2007-2009 Paul Brossier <piem@aubio.org>
3                      and Amaury Hazan <ahazan@iua.upf.edu>
4
5  This file is part of Aubio.
6
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.
11
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.
16
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/>.
19
20*/
21
22#include "aubio_priv.h"
23#include "fvec.h"
24#include "cvec.h"
25#include "spectral/fft.h"
26#include "spectral/filterbank_mel.h"
27#include "spectral/mfcc.h"
28
29/** Internal structure for mfcc object */
30
31struct aubio_mfcc_t_
32{
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 */
40};
41
42
43aubio_mfcc_t *
44new_aubio_mfcc (uint_t win_s, uint_t samplerate, uint_t n_filters,
45    uint_t n_coefs)
46{
47
48  /* allocate space for mfcc object */
49  aubio_mfcc_t *mfcc = AUBIO_NEW (aubio_mfcc_t);
50
51  uint_t i, j;
52
53  mfcc->win_s = win_s;
54  mfcc->samplerate = samplerate;
55  mfcc->n_filters = n_filters;
56  mfcc->n_coefs = n_coefs;
57
58  /* filterbank allocation */
59  mfcc->fb = new_aubio_filterbank (n_filters, mfcc->win_s);
60  aubio_filterbank_set_mel_coeffs_slaney (mfcc->fb, samplerate);
61
62  /* allocating buffers */
63  mfcc->in_dct = new_fvec (n_filters, 1);
64
65  mfcc->dct_coeffs = new_fvec (n_coefs, n_filters);
66
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);
74    }
75    mfcc->dct_coeffs->data[i][0] *= SQRT (2.) / 2.;
76  }
77
78  return mfcc;
79};
80
81void
82del_aubio_mfcc (aubio_mfcc_t * mf)
83{
84
85  /* delete filterbank */
86  del_aubio_filterbank (mf->fb);
87
88  /* delete buffers */
89  del_fvec (mf->in_dct);
90
91  /* delete mfcc object */
92  AUBIO_FREE (mf);
93}
94
95
96void
97aubio_mfcc_do (aubio_mfcc_t * mf, cvec_t * in, fvec_t * out)
98{
99  uint_t i, j;
100  /* compute filterbank */
101  aubio_filterbank_do (mf->fb, in, mf->in_dct);
102
103  /* extract real part of fft grain */
104  for (i = 0; i < mf->n_filters; i++) {
105    for (j = 0; j < mf->n_coefs; j++) {
106      out->data[0][j] += mf->in_dct->data[0][i]
107          * mf->dct_coeffs->data[i][j];
108    }
109  }
110
111  return;
112}
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