core.c

   1 /*
   2
   3     PROGRAM_NAME PROGRAM_VERSION - PROGRAM_DESCRIPTION
   4
   5     Copyright (C) 2003 Angel Ortega <angel@triptico.com>
   6
   7     This program is free software; you can redistribute it and/or
   8     modify it under the terms of the GNU General Public License
   9     as published by the Free Software Foundation; either version 2
  10     of the License, or (at your option) any later version.
  11
  12     This program 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 this program; if not, write to the Free Software
  19     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  20
  21     http://www.triptico.com
  22
  23 */
  24
  25 #include "config.h"
  26
  27 #include <stdio.h>
  28 #include <stdlib.h>
  29 #include <math.h>
  30
  31 #include "core.h"
  32
  33 /*******************
  34         Data
  35 ********************/
  36
  37 /* main output frequency */
  38 int _frequency=44100;
  39
  40 /* linear interpolation flag */
  41 int _linear_interpolation=1;
  42
  43 /*******************
  44         Code
  45 ********************/
  46
  47 int get_sample(int * wave, double size, double offset)
  48 {
  49         double d;
  50         double s1,s2;
  51
  52         if(!_linear_interpolation)
  53                 return(wave[(int) offset]);
  54
  55         if(offset > size) return(wave[(int)size]);
  56
  57         d=offset - floor(offset);
  58         s1=(double) (wave[(int)offset]) * (1 - d);
  59         s2=(double) (wave[(int)offset + 1]) * d;
  60
  61         return((int) (s1 + s2));
  62 }
  63
  64
  65 int * wave_resample(int * wave, int freq, int * size)
  66 {
  67         double ratio;
  68         int new_size;
  69         int * new_wave;
  70         int n;
  71         double i;
  72
  73         ratio=(double) freq / (double) _frequency;
  74         new_size=(int)((double) (*size) / ratio);
  75
  76         new_wave=(int *)malloc(new_size * sizeof(int));
  77
  78         printf("wave_resample: ratio %f\n", (float)ratio);
  79
  80         for(n=i=0;n < new_size;n++,i+=ratio)
  81                 new_wave[n]=get_sample(wave, *size, i);
  82
  83         *size=new_size;
  84
  85         /* free the old wave */
  86         free(wave);
  87
  88         return(new_wave);
  89 }