ref: ae6e15c80aa3700300828afe172fd5fad3b9cdc5
dir: /src/spectral/mfcc.c/
/* Copyright (C) 2007-2009 Paul Brossier <piem@aubio.org> and Amaury Hazan <ahazan@iua.upf.edu> This file is part of aubio. aubio is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. aubio is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with aubio. If not, see <http://www.gnu.org/licenses/>. */ #include "aubio_priv.h" #include "fvec.h" #include "cvec.h" #include "mathutils.h" #include "spectral/fft.h" #include "spectral/filterbank.h" #include "spectral/filterbank_mel.h" #include "spectral/mfcc.h" /** Internal structure for mfcc object */ struct _aubio_mfcc_t { uint_t win_s; /** grain length */ uint_t samplerate; /** sample rate (needed?) */ uint_t n_filters; /** number of *filters */ uint_t n_coefs; /** number of coefficients (<= n_filters/2 +1) */ aubio_filterbank_t *fb; /** filter bank */ fvec_t *in_dct; /** input buffer for dct * [fb->n_filters] */ fvec_t *dct_coeffs; /** DCT transform n_filters * n_coeffs */ }; aubio_mfcc_t * new_aubio_mfcc (uint_t win_s, uint_t samplerate, uint_t n_filters, uint_t n_coefs) { /* allocate space for mfcc object */ aubio_mfcc_t *mfcc = AUBIO_NEW (aubio_mfcc_t); uint_t i, j; mfcc->win_s = win_s; mfcc->samplerate = samplerate; mfcc->n_filters = n_filters; mfcc->n_coefs = n_coefs; /* filterbank allocation */ mfcc->fb = new_aubio_filterbank (n_filters, mfcc->win_s); aubio_filterbank_set_mel_coeffs_slaney (mfcc->fb, samplerate); /* allocating buffers */ mfcc->in_dct = new_fvec (n_filters, 1); mfcc->dct_coeffs = new_fvec (n_coefs, n_filters); /* compute DCT transform dct_coeffs[i][j] as cos ( j * (i+.5) * PI / n_filters ) */ smpl_t scaling = 1. / SQRT (n_filters / 2.); for (i = 0; i < n_filters; i++) { for (j = 0; j < n_coefs; j++) { mfcc->dct_coeffs->data[i][j] = scaling * COS (j * (i + 0.5) * PI / n_filters); } mfcc->dct_coeffs->data[i][0] *= SQRT (2.) / 2.; } return mfcc; }; void del_aubio_mfcc (aubio_mfcc_t * mf) { /* delete filterbank */ del_aubio_filterbank (mf->fb); /* delete buffers */ del_fvec (mf->in_dct); /* delete mfcc object */ AUBIO_FREE (mf); } void aubio_mfcc_do (aubio_mfcc_t * mf, cvec_t * in, fvec_t * out) { uint_t i, j; /* compute filterbank */ aubio_filterbank_do (mf->fb, in, mf->in_dct); /* compute log10 */ fvec_log10 (mf->in_dct); /* raise power */ //vec_pow (mf->in_dct, 3.); /* zeros output */ fvec_zeros(out); /* compute discrete cosine transform */ for (i = 0; i < mf->n_filters; i++) { for (j = 0; j < mf->n_coefs; j++) { out->data[0][j] += mf->in_dct->data[0][i] * mf->dct_coeffs->data[i][j]; } } return; }