source: src/spectral/filterbank_mel.c @ d95ff38

feature/autosinkfeature/cnnfeature/cnn_orgfeature/constantqfeature/crepefeature/crepe_orgfeature/pitchshiftfeature/pydocstringsfeature/timestretchfix/ffmpeg5pitchshiftsamplertimestretchyinfft+
Last change on this file since d95ff38 was d95ff38, checked in by Paul Brossier <piem@piem.org>, 14 years ago

src/spectral: switch to mono

  • Property mode set to 100644
File size: 6.0 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 "fmat.h"
24#include "fvec.h"
25#include "cvec.h"
26#include "spectral/filterbank.h"
27#include "mathutils.h"
28
29uint_t
30aubio_filterbank_set_triangle_bands (aubio_filterbank_t * fb,
31    fvec_t * freqs, smpl_t samplerate)
32{
33
34  fmat_t *filters = aubio_filterbank_get_coeffs (fb);
35  uint_t n_filters = filters->height, win_s = filters->length;
36
37  uint_t fn;                    /* filter counter */
38  uint_t bin;                   /* bin counter */
39
40  /* freqs define the bands of triangular overlapping windows.
41     throw a warning if filterbank object fb is too short. */
42  if (freqs->length - 2 > n_filters) {
43    AUBIO_WRN ("not enough filters, %d allocated but %d requested\n",
44        n_filters, freqs->length - 2);
45  }
46
47  if (freqs->length - 2 < n_filters) {
48    AUBIO_WRN ("too many filters, %d allocated but %d requested\n",
49        n_filters, freqs->length - 2);
50  }
51
52  if (freqs->data[freqs->length - 1] > samplerate / 2) {
53    AUBIO_WRN ("Nyquist frequency is %fHz, but highest frequency band ends at \
54%fHz\n", samplerate / 2, freqs->data[freqs->length - 1]);
55  }
56
57  /* convenience reference to lower/center/upper frequency for each triangle */
58  fvec_t *lower_freqs = new_fvec (n_filters);
59  fvec_t *upper_freqs = new_fvec (n_filters);
60  fvec_t *center_freqs = new_fvec (n_filters);
61
62  /* height of each triangle */
63  fvec_t *triangle_heights = new_fvec (n_filters);
64
65  /* lookup table of each bin frequency in hz */
66  fvec_t *fft_freqs = new_fvec (win_s);
67
68  /* fill up the lower/center/upper */
69  for (fn = 0; fn < n_filters; fn++) {
70    lower_freqs->data[fn] = freqs->data[fn];
71    center_freqs->data[fn] = freqs->data[fn + 1];
72    upper_freqs->data[fn] = freqs->data[fn + 2];
73  }
74
75  /* compute triangle heights so that each triangle has unit area */
76  for (fn = 0; fn < n_filters; fn++) {
77    triangle_heights->data[fn] =
78        2. / (upper_freqs->data[fn] - lower_freqs->data[fn]);
79  }
80
81  /* fill fft_freqs lookup table, which assigns the frequency in hz to each bin */
82  for (bin = 0; bin < win_s; bin++) {
83    fft_freqs->data[bin] =
84        aubio_bintofreq (bin, samplerate, (win_s - 1) * 2);
85  }
86
87  /* zeroing of all filters */
88  fmat_zeros (filters);
89
90  if (fft_freqs->data[1] >= lower_freqs->data[0]) {
91    /* - 1 to make sure we don't miss the smallest power of two */
92    uint_t min_win_s =
93        (uint_t) FLOOR (samplerate / lower_freqs->data[0]) - 1;
94    AUBIO_WRN ("Lowest frequency bin (%.2fHz) is higher than lowest frequency \
95band (%.2f-%.2fHz). Consider increasing the window size from %d to %d.\n",
96        fft_freqs->data[1], lower_freqs->data[0],
97        upper_freqs->data[0], (win_s - 1) * 2,
98        aubio_next_power_of_two (min_win_s));
99  }
100
101  /* building each filter table */
102  for (fn = 0; fn < n_filters; fn++) {
103
104    /* skip first elements */
105    for (bin = 0; bin < win_s - 1; bin++) {
106      if (fft_freqs->data[bin] <= lower_freqs->data[fn] &&
107          fft_freqs->data[bin + 1] > lower_freqs->data[fn]) {
108        bin++;
109        break;
110      }
111    }
112
113    /* compute positive slope step size */
114    smpl_t riseInc =
115        triangle_heights->data[fn] /
116        (center_freqs->data[fn] - lower_freqs->data[fn]);
117
118    /* compute coefficients in positive slope */
119    for (; bin < win_s - 1; bin++) {
120      filters->data[fn][bin] =
121          (fft_freqs->data[bin] - lower_freqs->data[fn]) * riseInc;
122
123      if (fft_freqs->data[bin + 1] >= center_freqs->data[fn]) {
124        bin++;
125        break;
126      }
127    }
128
129    /* compute negative slope step size */
130    smpl_t downInc =
131        triangle_heights->data[fn] /
132        (upper_freqs->data[fn] - center_freqs->data[fn]);
133
134    /* compute coefficents in negative slope */
135    for (; bin < win_s - 1; bin++) {
136      filters->data[fn][bin] +=
137          (upper_freqs->data[fn] - fft_freqs->data[bin]) * downInc;
138
139      if (filters->data[fn][bin] < 0.) {
140        filters->data[fn][bin] = 0.;
141      }
142
143      if (fft_freqs->data[bin + 1] >= upper_freqs->data[fn])
144        break;
145    }
146    /* nothing else to do */
147
148  }
149
150  /* destroy temporarly allocated vectors */
151  del_fvec (lower_freqs);
152  del_fvec (upper_freqs);
153  del_fvec (center_freqs);
154
155  del_fvec (triangle_heights);
156  del_fvec (fft_freqs);
157
158  return 0;
159}
160
161uint_t
162aubio_filterbank_set_mel_coeffs_slaney (aubio_filterbank_t * fb,
163    smpl_t samplerate)
164{
165  uint_t retval;
166
167  /* Malcolm Slaney parameters */
168  smpl_t lowestFrequency = 133.3333;
169  smpl_t linearSpacing = 66.66666666;
170  smpl_t logSpacing = 1.0711703;
171
172  uint_t linearFilters = 13;
173  uint_t logFilters = 27;
174  uint_t n_filters = linearFilters + logFilters;
175
176  uint_t fn;                    /* filter counter */
177
178  /* buffers to compute filter frequencies */
179  fvec_t *freqs = new_fvec (n_filters + 2);
180
181  /* first step: fill all the linear filter frequencies */
182  for (fn = 0; fn < linearFilters; fn++) {
183    freqs->data[fn] = lowestFrequency + fn * linearSpacing;
184  }
185  smpl_t lastlinearCF = freqs->data[fn - 1];
186
187  /* second step: fill all the log filter frequencies */
188  for (fn = 0; fn < logFilters + 2; fn++) {
189    freqs->data[fn + linearFilters] =
190        lastlinearCF * (POW (logSpacing, fn + 1));
191  }
192
193  /* now compute the actual coefficients */
194  retval = aubio_filterbank_set_triangle_bands (fb, freqs, samplerate);
195
196  /* destroy vector used to store frequency limits */
197  del_fvec (freqs);
198
199  return retval;
200}
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