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"
26 #include "spectral/filterbank.h"
27 #include "spectral/filterbank_mel.h"
28 #include "mathutils.h"
31 aubio_filterbank_set_triangle_bands (aubio_filterbank_t * fb,
32 const fvec_t * freqs, smpl_t samplerate)
35 fmat_t *filters = aubio_filterbank_get_coeffs (fb);
36 uint_t n_filters = filters->height, win_s = filters->length;
37 fvec_t *lower_freqs, *upper_freqs, *center_freqs;
38 fvec_t *triangle_heights, *fft_freqs;
40 uint_t fn; /* filter counter */
41 uint_t bin; /* bin counter */
43 smpl_t riseInc, downInc;
45 /* freqs define the bands of triangular overlapping windows.
46 throw a warning if filterbank object fb is too short. */
47 if (freqs->length - 2 > n_filters) {
48 AUBIO_WRN ("not enough filters, %d allocated but %d requested\n",
49 n_filters, freqs->length - 2);
52 if (freqs->length - 2 < n_filters) {
53 AUBIO_WRN ("too many filters, %d allocated but %d requested\n",
54 n_filters, freqs->length - 2);
57 if (freqs->data[freqs->length - 1] > samplerate / 2) {
58 AUBIO_WRN ("Nyquist frequency is %fHz, but highest frequency band ends at \
59 %fHz\n", samplerate / 2, freqs->data[freqs->length - 1]);
62 /* convenience reference to lower/center/upper frequency for each triangle */
63 lower_freqs = new_fvec (n_filters);
64 upper_freqs = new_fvec (n_filters);
65 center_freqs = new_fvec (n_filters);
67 /* height of each triangle */
68 triangle_heights = new_fvec (n_filters);
70 /* lookup table of each bin frequency in hz */
71 fft_freqs = new_fvec (win_s);
73 /* fill up the lower/center/upper */
74 for (fn = 0; fn < n_filters; fn++) {
75 lower_freqs->data[fn] = freqs->data[fn];
76 center_freqs->data[fn] = freqs->data[fn + 1];
77 upper_freqs->data[fn] = freqs->data[fn + 2];
80 /* compute triangle heights so that each triangle has unit area */
81 for (fn = 0; fn < n_filters; fn++) {
82 triangle_heights->data[fn] =
83 2. / (upper_freqs->data[fn] - lower_freqs->data[fn]);
86 /* fill fft_freqs lookup table, which assigns the frequency in hz to each bin */
87 for (bin = 0; bin < win_s; bin++) {
88 fft_freqs->data[bin] =
89 aubio_bintofreq (bin, samplerate, (win_s - 1) * 2);
92 /* zeroing of all filters */
95 if (fft_freqs->data[1] >= lower_freqs->data[0]) {
96 /* - 1 to make sure we don't miss the smallest power of two */
98 (uint_t) FLOOR (samplerate / lower_freqs->data[0]) - 1;
99 AUBIO_WRN ("Lowest frequency bin (%.2fHz) is higher than lowest frequency \
100 band (%.2f-%.2fHz). Consider increasing the window size from %d to %d.\n",
101 fft_freqs->data[1], lower_freqs->data[0],
102 upper_freqs->data[0], (win_s - 1) * 2,
103 aubio_next_power_of_two (min_win_s));
106 /* building each filter table */
107 for (fn = 0; fn < n_filters; fn++) {
109 /* skip first elements */
110 for (bin = 0; bin < win_s - 1; bin++) {
111 if (fft_freqs->data[bin] <= lower_freqs->data[fn] &&
112 fft_freqs->data[bin + 1] > lower_freqs->data[fn]) {
118 /* compute positive slope step size */
120 triangle_heights->data[fn] /
121 (center_freqs->data[fn] - lower_freqs->data[fn]);
123 /* compute coefficients in positive slope */
124 for (; bin < win_s - 1; bin++) {
125 filters->data[fn][bin] =
126 (fft_freqs->data[bin] - lower_freqs->data[fn]) * riseInc;
128 if (fft_freqs->data[bin + 1] >= center_freqs->data[fn]) {
134 /* compute negative slope step size */
136 triangle_heights->data[fn] /
137 (upper_freqs->data[fn] - center_freqs->data[fn]);
139 /* compute coefficents in negative slope */
140 for (; bin < win_s - 1; bin++) {
141 filters->data[fn][bin] +=
142 (upper_freqs->data[fn] - fft_freqs->data[bin]) * downInc;
144 if (filters->data[fn][bin] < 0.) {
145 filters->data[fn][bin] = 0.;
148 if (fft_freqs->data[bin + 1] >= upper_freqs->data[fn])
151 /* nothing else to do */
155 /* destroy temporarly allocated vectors */
156 del_fvec (lower_freqs);
157 del_fvec (upper_freqs);
158 del_fvec (center_freqs);
160 del_fvec (triangle_heights);
161 del_fvec (fft_freqs);
167 aubio_filterbank_set_mel_coeffs_slaney (aubio_filterbank_t * fb,
172 /* Malcolm Slaney parameters */
173 smpl_t lowestFrequency = 133.3333;
174 smpl_t linearSpacing = 66.66666666;
175 smpl_t logSpacing = 1.0711703;
177 uint_t linearFilters = 13;
178 uint_t logFilters = 27;
179 uint_t n_filters = linearFilters + logFilters;
181 uint_t fn; /* filter counter */
185 /* buffers to compute filter frequencies */
186 fvec_t *freqs = new_fvec (n_filters + 2);
188 /* first step: fill all the linear filter frequencies */
189 for (fn = 0; fn < linearFilters; fn++) {
190 freqs->data[fn] = lowestFrequency + fn * linearSpacing;
192 lastlinearCF = freqs->data[fn - 1];
194 /* second step: fill all the log filter frequencies */
195 for (fn = 0; fn < logFilters + 2; fn++) {
196 freqs->data[fn + linearFilters] =
197 lastlinearCF * (POW (logSpacing, fn + 1));
200 /* now compute the actual coefficients */
201 retval = aubio_filterbank_set_triangle_bands (fb, freqs, samplerate);
203 /* destroy vector used to store frequency limits */