interpretor/libsndfile-1.0.25/tests/generate.c

   1 /*
   2 ** Copyright (C) 2007-2011 Erik de Castro Lopo <erikd@mega-nerd.com>
   3 **
   4 ** This program is free software; you can redistribute it and/or modify
   5 ** it under the terms of the GNU General Public License as published by
   6 ** the Free Software Foundation; either version 2 of the License, or
   7 ** (at your option) any later version.
   8 **
   9 ** This program is distributed in the hope that it will be useful,
  10 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 ** GNU General Public License for more details.
  13 **
  14 ** You should have received a copy of the GNU General Public License
  15 ** along with this program; if not, write to the Free Software
  16 ** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17 */
  18
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <math.h>
  23
  24 #include <sndfile.h>
  25
  26 #include "utils.h"
  27 #include "generate.h"
  28
  29 #define SF_MAX(x,y)             ((x) > (y) ? (x) : (y))
  30
  31 static float crappy_snare (float *output, int len, int offset, float gain, float maxabs) ;
  32
  33 void
  34 generate_file (const char * filename, int format, int len)
  35 {       float * output ;
  36         float maxabs = 0.0 ;
  37
  38         output = calloc (len, sizeof (float)) ;
  39
  40         maxabs = crappy_snare (output, len, 0, 0.95, maxabs) ;
  41         maxabs = crappy_snare (output, len, len / 4, 0.85, maxabs) ;
  42         maxabs = crappy_snare (output, len, 2 * len / 4, 0.85, maxabs) ;
  43         crappy_snare (output, len, 3 * len / 4, 0.85, maxabs) ;
  44
  45         write_mono_file (filename, format, 44100, output, len) ;
  46
  47         free (output) ;
  48 } /* generate_file */
  49
  50 static inline float
  51 rand_float (void)
  52 {       return rand () / (0.5 * RAND_MAX) - 1.0 ;
  53 } /* rand_float */
  54
  55 static float
  56 crappy_snare (float *output, int len, int offset, float gain, float maxabs)
  57 {       int k ;
  58         float env = 0.0 ;
  59
  60         for (k = offset ; k < len && env < gain ; k++)
  61         {       env += 0.03 ;
  62                 output [k] += env * rand_float () ;
  63                 maxabs = SF_MAX (maxabs, fabs (output [k])) ;
  64                 } ;
  65
  66         for ( ; k < len && env > 1e-8 ; k++)
  67         {       env *= 0.995 ;
  68                 output [k] += env * rand_float () ;
  69                 maxabs = SF_MAX (maxabs, fabs (output [k])) ;
  70                 } ;
  71
  72         return maxabs ;
  73 } /* crappy_snare */