src/spectral/filterbank.c

   1 /*
   2    Copyright (C) 2007 Amaury Hazan <ahazan@iua.upf.edu>
   3                   and Paul Brossier <piem@piem.org>
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 2 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, write to the Free Software
  17    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18
  19 */
  20
  21
  22 #include "aubio_priv.h"
  23 #include "fvec.h"
  24 #include "cvec.h"
  25 #include "spectral/filterbank.h"
  26 #include "mathutils.h"
  27
  28 #define VERY_SMALL_NUMBER 2e-42
  29
  30 /** \brief A structure to store a set of n_filters filters of lenghts win_s */
  31 struct aubio_filterbank_t_ {
  32     uint_t win_s;
  33     uint_t n_filters;
  34     fvec_t **filters;
  35 };
  36
  37 aubio_filterbank_t * new_aubio_filterbank(uint_t n_filters, uint_t win_s){
  38   /** allocating space for filterbank object */
  39   aubio_filterbank_t * fb = AUBIO_NEW(aubio_filterbank_t);
  40   uint_t filter_cnt;
  41   fb->win_s=win_s;
  42   fb->n_filters=n_filters;
  43
  44   /** allocating filter tables */
  45   fb->filters=AUBIO_ARRAY(fvec_t*,n_filters);
  46   for (filter_cnt=0; filter_cnt<n_filters; filter_cnt++)
  47     /* considering one-channel filters */
  48     fb->filters[filter_cnt]=new_fvec(win_s, 1);
  49
  50   return fb;
  51 }
  52
  53 /*
  54 FB initialization based on Slaney's auditory toolbox
  55 TODO:
  56   *solve memory leak problems while
  57   *solve quantization issues when constructing signal:
  58     *bug for win_s=512
  59     *corrections for win_s=1024 -> why even filters with smaller amplitude
  60
  61 */
  62
  63 aubio_filterbank_t * new_aubio_filterbank_mfcc(uint_t n_filters, uint_t win_s, uint_t samplerate, smpl_t freq_min, smpl_t freq_max){
  64
  65   aubio_filterbank_t * fb = new_aubio_filterbank(n_filters, win_s);
  66
  67
  68   //slaney params
  69   smpl_t lowestFrequency = 133.3333;
  70   smpl_t linearSpacing = 66.66666666;
  71   smpl_t logSpacing = 1.0711703;
  72
  73   uint_t linearFilters = 13;
  74   uint_t logFilters = 27;
  75   uint_t allFilters = linearFilters + logFilters;
  76
  77   //buffers for computing filter frequencies
  78   fvec_t * freqs=new_fvec(allFilters+2 , 1);
  79
  80   fvec_t * lower_freqs=new_fvec( allFilters, 1);
  81   fvec_t * upper_freqs=new_fvec( allFilters, 1);
  82   fvec_t * center_freqs=new_fvec( allFilters, 1);
  83
  84   fvec_t * triangle_heights=new_fvec( allFilters, 1);
  85   //lookup table of each bin frequency in hz
  86   fvec_t * fft_freqs=new_fvec(win_s, 1);
  87
  88   uint_t filter_cnt, bin_cnt;
  89
  90   //first step: filling all the linear filter frequencies
  91   for(filter_cnt=0; filter_cnt<linearFilters; filter_cnt++){
  92     freqs->data[0][filter_cnt]=lowestFrequency+ filter_cnt*linearSpacing;
  93   }
  94   smpl_t lastlinearCF=freqs->data[0][filter_cnt-1];
  95
  96   //second step: filling all the log filter frequencies
  97   for(filter_cnt=0; filter_cnt<logFilters+2; filter_cnt++){
  98     freqs->data[0][filter_cnt+linearFilters] =
  99       lastlinearCF*(pow(logSpacing,filter_cnt+1));
 100   }
 101
 102   //Option 1. copying interesting values to lower_freqs, center_freqs and upper freqs arrays
 103   //TODO: would be nicer to have a reference to freqs->data, anyway we do not care in this init step
 104
 105   for(filter_cnt=0; filter_cnt<allFilters; filter_cnt++){
 106     lower_freqs->data[0][filter_cnt]=freqs->data[0][filter_cnt];
 107     center_freqs->data[0][filter_cnt]=freqs->data[0][filter_cnt+1];
 108     upper_freqs->data[0][filter_cnt]=freqs->data[0][filter_cnt+2];
 109   }
 110
 111   //computing triangle heights so that each triangle has unit area
 112   for(filter_cnt=0; filter_cnt<allFilters; filter_cnt++){
 113     triangle_heights->data[0][filter_cnt] = 2./(upper_freqs->data[0][filter_cnt]
 114       - lower_freqs->data[0][filter_cnt]);
 115   }
 116
 117   //AUBIO_DBG("filter tables frequencies\n");
 118   //for(filter_cnt=0; filter_cnt<allFilters; filter_cnt++)
 119   //  AUBIO_DBG("filter n. %d %f %f %f %f\n",
 120   //    filter_cnt, lower_freqs->data[0][filter_cnt],
 121   //    center_freqs->data[0][filter_cnt], upper_freqs->data[0][filter_cnt],
 122   //    triangle_heights->data[0][filter_cnt]);
 123
 124   //filling the fft_freqs lookup table, which assigns the frequency in hz to each bin
 125   for(bin_cnt=0; bin_cnt<win_s; bin_cnt++){
 126     fft_freqs->data[0][bin_cnt]= aubio_bintofreq(bin_cnt, samplerate, win_s);
 127   }
 128
 129   //building each filter table
 130   for(filter_cnt=0; filter_cnt<allFilters; filter_cnt++){
 131
 132     //TODO:check special case : lower freq =0
 133     //calculating rise increment in mag/Hz
 134     smpl_t riseInc= triangle_heights->data[0][filter_cnt]/(center_freqs->data[0][filter_cnt]-lower_freqs->data[0][filter_cnt]);
 135
 136     //zeroing begining of filter
 137     for(bin_cnt=0; bin_cnt<win_s-1; bin_cnt++){
 138       fb->filters[filter_cnt]->data[0][bin_cnt]=0.f;
 139       if( fft_freqs->data[0][bin_cnt]  <= lower_freqs->data[0][filter_cnt] &&
 140           fft_freqs->data[0][bin_cnt+1] > lower_freqs->data[0][filter_cnt]) {
 141         break;
 142       }
 143     }
 144     bin_cnt++;
 145
 146     //positive slope
 147     for(; bin_cnt<win_s-1; bin_cnt++){
 148       fb->filters[filter_cnt]->data[0][bin_cnt]=(fft_freqs->data[0][bin_cnt]-lower_freqs->data[0][filter_cnt])*riseInc;
 149       //if(fft_freqs->data[0][bin_cnt]<= center_freqs->data[0][filter_cnt] && fft_freqs->data[0][bin_cnt+1]> center_freqs->data[0][filter_cnt])
 150       if(fft_freqs->data[0][bin_cnt+1]> center_freqs->data[0][filter_cnt])
 151         break;
 152     }
 153     //bin_cnt++;
 154
 155     //negative slope
 156     for(; bin_cnt<win_s-1; bin_cnt++){
 157
 158       //checking whether last value is less than 0...
 159       smpl_t val=triangle_heights->data[0][filter_cnt]-(fft_freqs->data[0][bin_cnt]-center_freqs->data[0][filter_cnt])*riseInc;
 160       if(val>=0)
 161         fb->filters[filter_cnt]->data[0][bin_cnt]=val;
 162       else fb->filters[filter_cnt]->data[0][bin_cnt]=0.f;
 163
 164       //if(fft_freqs->data[0][bin_cnt]<= upper_freqs->data[0][bin_cnt] && fft_freqs->data[0][bin_cnt+1]> upper_freqs->data[0][filter_cnt])
 165       //TODO: CHECK whether bugfix correct
 166       if(fft_freqs->data[0][bin_cnt+1]> upper_freqs->data[0][filter_cnt])
 167         break;
 168     }
 169     //bin_cnt++;
 170
 171     //zeroing tail
 172     for(; bin_cnt<win_s; bin_cnt++)
 173       fb->filters[filter_cnt]->data[0][bin_cnt]=0.f;
 174
 175   }
 176
 177
 178   del_fvec(freqs);
 179   del_fvec(lower_freqs);
 180   del_fvec(upper_freqs);
 181   del_fvec(center_freqs);
 182
 183   del_fvec(triangle_heights);
 184   del_fvec(fft_freqs);
 185
 186   return fb;
 187
 188 }
 189
 190 void del_aubio_filterbank(aubio_filterbank_t * fb){
 191   uint_t filter_cnt;
 192   /** deleting filter tables first */
 193   for (filter_cnt=0; filter_cnt<fb->n_filters; filter_cnt++)
 194     del_fvec(fb->filters[filter_cnt]);
 195   AUBIO_FREE(fb->filters);
 196   AUBIO_FREE(fb);
 197 }
 198
 199 void aubio_filterbank_do(aubio_filterbank_t * f, cvec_t * in, fvec_t *out) {
 200   uint_t n, filter_cnt;
 201   for(filter_cnt = 0; (filter_cnt < f->n_filters)
 202     && (filter_cnt < out->length); filter_cnt++){
 203       out->data[0][filter_cnt] = 0.f;
 204       for(n = 0; n < in->length; n++){
 205           out->data[0][filter_cnt] += in->norm[0][n]
 206             * f->filters[filter_cnt]->data[0][n];
 207       }
 208       out->data[0][filter_cnt] =
 209         LOG(out->data[0][filter_cnt] < VERY_SMALL_NUMBER ?
 210             VERY_SMALL_NUMBER : out->data[0][filter_cnt]);
 211   }
 212
 213   return;
 214 }
 215
 216 fvec_t * aubio_filterbank_getchannel(aubio_filterbank_t * f, uint_t channel) {
 217   if ( (channel < f->n_filters) ) { return f->filters[channel]; }
 218   else { return NULL; }
 219 }