1 | /* |
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2 | Copyright (C) 2006 Amaury Hazan |
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3 | Ported to aubio from LibXtract |
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4 | http://libxtract.sourceforge.net/ |
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5 | |
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6 | |
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7 | This program is free software; you can redistribute it and/or modify |
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8 | it under the terms of the GNU General Public License as published by |
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9 | the Free Software Foundation; either version 2 of the License, or |
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10 | (at your option) any later version. |
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11 | |
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12 | This program is distributed in the hope that it will be useful, |
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13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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15 | GNU General Public License for more details. |
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16 | |
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17 | You should have received a copy of the GNU General Public License |
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18 | along with this program; if not, write to the Free Software |
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19 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
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20 | |
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21 | */ |
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22 | |
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23 | #include "aubio_priv.h" |
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24 | #include "fvec.h" |
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25 | #include "cvec.h" |
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26 | #include "spectral/fft.h" |
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27 | #include "spectral/filterbank_mel.h" |
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28 | #include "spectral/mfcc.h" |
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29 | |
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30 | /** Internal structure for mfcc object **/ |
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31 | |
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32 | struct aubio_mfcc_t_{ |
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33 | uint_t win_s; /** grain length */ |
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34 | uint_t samplerate; /** sample rate (needed?) */ |
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35 | uint_t n_filters; /** number of *filters */ |
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36 | uint_t n_coefs; /** number of coefficients (<= n_filters/2 +1) */ |
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37 | aubio_filterbank_t * fb; /** filter bank */ |
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38 | fvec_t * in_dct; /** input buffer for dct * [fb->n_filters] */ |
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39 | fvec_t * dct_coeffs; /** DCT transform n_filters * n_coeffs */ |
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40 | }; |
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41 | |
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42 | |
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43 | aubio_mfcc_t * new_aubio_mfcc (uint_t win_s, uint_t samplerate, uint_t n_filters, uint_t n_coefs){ |
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44 | |
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45 | uint_t i, j; |
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46 | |
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47 | /** allocating space for mfcc object */ |
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48 | aubio_mfcc_t * mfcc = AUBIO_NEW(aubio_mfcc_t); |
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49 | |
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50 | //we need (n_coefs-1)*2 filters to obtain n_coefs coefficients after dct |
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51 | //uint_t n_filters = (n_coefs-1)*2; |
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52 | |
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53 | mfcc->win_s=win_s; |
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54 | mfcc->samplerate=samplerate; |
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55 | mfcc->n_filters=n_filters; |
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56 | mfcc->n_coefs=n_coefs; |
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57 | |
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58 | |
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59 | /** filterbank allocation */ |
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60 | mfcc->fb = new_aubio_filterbank(n_filters, mfcc->win_s); |
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61 | aubio_filterbank_set_mel_coeffs_slaney(mfcc->fb, samplerate); |
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62 | |
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63 | /** allocating buffers */ |
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64 | mfcc->in_dct=new_fvec(n_filters, 1); |
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65 | |
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66 | mfcc->dct_coeffs = new_fvec(n_coefs, n_filters); |
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67 | |
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68 | |
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69 | /* compute DCT transform dct_coeffs[i][j] as |
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70 | cos ( j * (i+.5) * PI / n_filters ) |
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71 | */ |
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72 | smpl_t scaling = 1./SQRT(n_filters/2.); |
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73 | for (i = 0; i < n_filters; i++) { |
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74 | for (j = 0; j < n_coefs; j++) { |
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75 | mfcc->dct_coeffs->data[i][j] = |
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76 | scaling * COS (j * (i + 0.5) * PI / n_filters); |
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77 | } |
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78 | mfcc->dct_coeffs->data[i][0] *= SQRT(2.)/2.; |
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79 | } |
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80 | |
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81 | return mfcc; |
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82 | }; |
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83 | |
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84 | void del_aubio_mfcc(aubio_mfcc_t *mf){ |
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85 | /** deleting filterbank */ |
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86 | del_aubio_filterbank(mf->fb); |
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87 | /** deleting buffers */ |
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88 | del_fvec(mf->in_dct); |
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89 | |
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90 | /** deleting mfcc object */ |
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91 | AUBIO_FREE(mf); |
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92 | } |
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93 | |
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94 | |
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95 | void aubio_mfcc_do(aubio_mfcc_t * mf, cvec_t *in, fvec_t *out){ |
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96 | uint_t i, j; |
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97 | // compute filterbank |
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98 | aubio_filterbank_do(mf->fb, in, mf->in_dct); |
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99 | |
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100 | //extract real part of fft grain |
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101 | for (i = 0; i < mf->n_filters; i++) { |
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102 | for (j = 0; j < mf->n_coefs; j++) { |
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103 | out->data[0][j] += mf->in_dct->data[0][i] |
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104 | * mf->dct_coeffs->data[i][j]; |
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105 | } |
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106 | } |
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107 | |
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108 | return; |
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109 | } |
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