source: src/spectral/filterbank_mel.c @ 9ef3c6e

feature/autosinkfeature/constantqfeature/pitchshiftfeature/pydocstringsfeature/timestretch
Last change on this file since 9ef3c6e was 9ef3c6e, checked in by Paul Brossier <piem@piem.org>, 21 months ago

[filterbank] add a warning for duplicate freqs, improve nyquist warning

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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 "fmat.h"
24#include "fvec.h"
25#include "cvec.h"
26#include "spectral/filterbank.h"
27#include "spectral/filterbank_mel.h"
28#include "mathutils.h"
29
30uint_t
31aubio_filterbank_set_triangle_bands (aubio_filterbank_t * fb,
32    const fvec_t * freqs, smpl_t samplerate)
33{
34
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;
39
40  uint_t fn;                    /* filter counter */
41  uint_t bin;                   /* bin counter */
42
43  smpl_t riseInc, downInc;
44
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);
50  }
51
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);
55  }
56
57  for (fn = 0; fn < freqs->length; fn++) {
58    if (freqs->data[fn] < 0) {
59      AUBIO_ERR("filterbank_mel: freqs must contain only positive values.\n");
60      return AUBIO_FAIL;
61    } else if (freqs->data[fn] > samplerate / 2) {
62      AUBIO_WRN("filterbank_mel: freqs should contain only "
63          "values < samplerate / 2.\n");
64    } else if (fn > 0 && freqs->data[fn] < freqs->data[fn-1]) {
65      AUBIO_ERR("filterbank_mel: freqs should be a list of frequencies "
66          "sorted from low to high, but freq[%d] < freq[%d-1]\n", fn, fn);
67      return AUBIO_FAIL;
68    } else if (fn > 0 && freqs->data[fn] == freqs->data[fn-1]) {
69      AUBIO_WRN("filterbank_mel: set_triangle_bands received a list "
70          "with twice the frequency %f\n", freqs->data[fn]);
71    }
72  }
73
74  /* convenience reference to lower/center/upper frequency for each triangle */
75  lower_freqs = new_fvec (n_filters);
76  upper_freqs = new_fvec (n_filters);
77  center_freqs = new_fvec (n_filters);
78
79  /* height of each triangle */
80  triangle_heights = new_fvec (n_filters);
81
82  /* lookup table of each bin frequency in hz */
83  fft_freqs = new_fvec (win_s);
84
85  /* fill up the lower/center/upper */
86  for (fn = 0; fn < n_filters; fn++) {
87    lower_freqs->data[fn] = freqs->data[fn];
88    center_freqs->data[fn] = freqs->data[fn + 1];
89    upper_freqs->data[fn] = freqs->data[fn + 2];
90  }
91
92  /* compute triangle heights so that each triangle has unit area */
93  for (fn = 0; fn < n_filters; fn++) {
94    triangle_heights->data[fn] =
95        2. / (upper_freqs->data[fn] - lower_freqs->data[fn]);
96  }
97
98  /* fill fft_freqs lookup table, which assigns the frequency in hz to each bin */
99  for (bin = 0; bin < win_s; bin++) {
100    fft_freqs->data[bin] =
101        aubio_bintofreq (bin, samplerate, (win_s - 1) * 2);
102  }
103
104  /* zeroing of all filters */
105  fmat_zeros (filters);
106
107  /* building each filter table */
108  for (fn = 0; fn < n_filters; fn++) {
109
110    /* skip first elements */
111    for (bin = 0; bin < win_s - 1; bin++) {
112      if (fft_freqs->data[bin] <= lower_freqs->data[fn] &&
113          fft_freqs->data[bin + 1] > lower_freqs->data[fn]) {
114        bin++;
115        break;
116      }
117    }
118
119    /* compute positive slope step size */
120    riseInc =
121        triangle_heights->data[fn] /
122        (center_freqs->data[fn] - lower_freqs->data[fn]);
123
124    /* compute coefficients in positive slope */
125    for (; bin < win_s - 1; bin++) {
126      filters->data[fn][bin] =
127          (fft_freqs->data[bin] - lower_freqs->data[fn]) * riseInc;
128
129      if (fft_freqs->data[bin + 1] >= center_freqs->data[fn]) {
130        bin++;
131        break;
132      }
133    }
134
135    /* compute negative slope step size */
136    downInc =
137        triangle_heights->data[fn] /
138        (upper_freqs->data[fn] - center_freqs->data[fn]);
139
140    /* compute coefficents in negative slope */
141    for (; bin < win_s - 1; bin++) {
142      filters->data[fn][bin] +=
143          (upper_freqs->data[fn] - fft_freqs->data[bin]) * downInc;
144
145      if (filters->data[fn][bin] < 0.) {
146        filters->data[fn][bin] = 0.;
147      }
148
149      if (fft_freqs->data[bin + 1] >= upper_freqs->data[fn])
150        break;
151    }
152    /* nothing else to do */
153
154  }
155
156  /* destroy temporarly allocated vectors */
157  del_fvec (lower_freqs);
158  del_fvec (upper_freqs);
159  del_fvec (center_freqs);
160
161  del_fvec (triangle_heights);
162  del_fvec (fft_freqs);
163
164  return AUBIO_OK;
165}
166
167uint_t
168aubio_filterbank_set_mel_coeffs_slaney (aubio_filterbank_t * fb,
169    smpl_t samplerate)
170{
171  uint_t retval;
172
173  /* Malcolm Slaney parameters */
174  smpl_t lowestFrequency = 133.3333;
175  smpl_t linearSpacing = 66.66666666;
176  smpl_t logSpacing = 1.0711703;
177
178  uint_t linearFilters = 13;
179  uint_t logFilters = 27;
180  uint_t n_filters = linearFilters + logFilters;
181
182  uint_t fn;                    /* filter counter */
183
184  smpl_t lastlinearCF;
185
186  /* buffers to compute filter frequencies */
187  fvec_t *freqs = new_fvec (n_filters + 2);
188
189  /* first step: fill all the linear filter frequencies */
190  for (fn = 0; fn < linearFilters; fn++) {
191    freqs->data[fn] = lowestFrequency + fn * linearSpacing;
192  }
193  lastlinearCF = freqs->data[fn - 1];
194
195  /* second step: fill all the log filter frequencies */
196  for (fn = 0; fn < logFilters + 2; fn++) {
197    freqs->data[fn + linearFilters] =
198        lastlinearCF * (POW (logSpacing, fn + 1));
199  }
200
201  /* now compute the actual coefficients */
202  retval = aubio_filterbank_set_triangle_bands (fb, freqs, samplerate);
203
204  /* destroy vector used to store frequency limits */
205  del_fvec (freqs);
206
207  return retval;
208}
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