c/sampler/ao_example.c

   1 /*
   2  *
   3  * ao_example.c
   4  *
   5  *     Written by Stan Seibert - July 2001
   6  *
   7  * Legal Terms:
   8  *
   9  *     This source file is released into the public domain.  It is
  10  *     distributed without any warranty; without even the implied
  11  *     warranty * of merchantability or fitness for a particular
  12  *     purpose.
  13  *
  14  * Function:
  15  *
  16  *     This program opens the default driver and plays a 440 Hz tone for
  17  *     one second.
  18  *
  19  * Compilation command line (for Linux systems):
  20  *
  21  *     gcc -lao -ldl -lm -o ao_example ao_example.c
  22  *
  23  */
  24
  25 #include <stdio.h>
  26 #include <ao/ao.h>
  27 #include <math.h>
  28
  29 #define BUF_SIZE 4096
  30
  31 int main(int argc, char **argv)
  32 {
  33         ao_device *device;
  34         ao_sample_format format;
  35         int default_driver;
  36         char *buffer;
  37         int buf_size;
  38         int sample;
  39         float freq = 440.0;
  40         int i;
  41
  42         /* -- Initialize -- */
  43
  44         fprintf(stderr, "libao example program\n");
  45
  46         ao_initialize();
  47
  48         /* -- Setup for default driver -- */
  49
  50         default_driver = ao_default_driver_id();
  51
  52         format.bits = 16;
  53         format.channels = 2;
  54         format.rate = 44100;
  55         format.byte_format = AO_FMT_LITTLE;
  56
  57         /* -- Open driver -- */
  58         device = ao_open_live(default_driver, &format, NULL /* no options */);
  59         if (device == NULL) {
  60                 fprintf(stderr, "Error opening device.\n");
  61                 return 1;
  62         }
  63
  64         /* -- Play some stuff -- */
  65         buf_size = format.bits/8 * format.channels * format.rate;
  66         buffer = calloc(buf_size,
  67                         sizeof(char));
  68
  69         for (i = 0; i < format.rate; i++) {
  70                 sample = (int)(0.75 * 32768.0 *
  71                         sin(2 * M_PI * freq * ((float) i/format.rate)));
  72
  73                 /* Put the same stuff in left and right channel */
  74                 buffer[4*i] = buffer[4*i+2] = sample & 0xff;
  75                 buffer[4*i+1] = buffer[4*i+3] = (sample >> 8) & 0xff;
  76         }
  77         ao_play(device, buffer, buf_size);
  78
  79         /* -- Close and shutdown -- */
  80         ao_close(device);
  81
  82         ao_shutdown();
  83
  84   return (0);
  85 }