c/ghetto-sound-system/beatdetect.c

   1 //CFLAGS=-lasound make beatdetect; echo -----; ./beatdetect hw:default
   2 //http://www.equalarea.com/paul/alsa-audio.html
   3
   4         #include <stdio.h>
   5         #include <stdlib.h>
   6         #include <alsa/asoundlib.h>
   7
   8         main (int argc, char *argv[])
   9         {
  10                 int i;
  11                 int err;
  12                 short buf[128];
  13                 snd_pcm_t *capture_handle;
  14                 snd_pcm_hw_params_t *hw_params;
  15
  16                 if ((err = snd_pcm_open (&capture_handle, argv[1], SND_PCM_STREAM_CAPTURE, 0)) < 0) {
  17                         fprintf (stderr, "cannot open audio device %s (%s)\n",
  18                                  argv[1],
  19                                  snd_strerror (err));
  20                         exit (1);
  21                 }
  22                 if ((err = snd_pcm_hw_params_malloc (&hw_params)) < 0) {
  23                         fprintf (stderr, "cannot allocate hardware parameter structure (%s)\n",
  24                                  snd_strerror (err));
  25                         exit (1);
  26                 }
  27
  28                 if ((err = snd_pcm_hw_params_any (capture_handle, hw_params)) < 0) {
  29                         fprintf (stderr, "cannot initialize hardware parameter structure (%s)\n",
  30                                  snd_strerror (err));
  31                         exit (1);
  32                 }
  33
  34                 if ((err = snd_pcm_hw_params_set_access (capture_handle, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED)) < 0) {
  35                         fprintf (stderr, "cannot set access type (%s)\n",
  36                                  snd_strerror (err));
  37                         exit (1);
  38                 }
  39
  40                 if ((err = snd_pcm_hw_params_set_format (capture_handle, hw_params, SND_PCM_FORMAT_S16_LE)) < 0) { //SND_PCM_FORMAT_S16_LE
  41                         fprintf (stderr, "cannot set sample format (%s)\n",
  42                                  snd_strerror (err));
  43                         exit (1);
  44                 }
  45
  46 /*                         puts("lolopre");
  47                 if ((err = snd_pcm_hw_params_set_rate_near (capture_handle, hw_params, 44100, 0)) < 0) {
  48                            puts("loloerr");
  49                         fprintf (stderr, "cannot set sample rate (%s)\n",
  50                                  snd_strerror (err));
  51                         exit (1);
  52                 }
  53
  54                 if ((err = snd_pcm_hw_params_set_channels (capture_handle, hw_params, 2)) < 0) {
  55                         fprintf (stderr, "cannot set channel count (%s)\n",
  56                                  snd_strerror (err));
  57                         exit (1);
  58                 }
  59 */
  60
  61                 if ((err = snd_pcm_hw_params (capture_handle, hw_params)) < 0) {
  62                         fprintf (stderr, "cannot set parameters (%s)\n",
  63                                  snd_strerror (err));
  64                         exit (1);
  65                 }
  66
  67                 snd_pcm_hw_params_free (hw_params);
  68
  69                 if ((err = snd_pcm_prepare (capture_handle)) < 0) {
  70                         fprintf (stderr, "cannot prepare audio interface for use (%s)\n",
  71                                  snd_strerror (err));
  72                         exit (1);
  73                 }
  74
  75                 //for (i = 0; i < 10; ++i) {
  76                 for (i = 0; 1; ++i) {
  77                         if ((err = snd_pcm_readi (capture_handle, buf, 128)) != 128) {
  78                                 fprintf (stderr, "read from audio interface failed (%s)\n", snd_strerror (err));
  79                                 exit (1);
  80                         } else {
  81                                 int j;
  82                                 for(j=0;j<128;j++) if((int)buf[j] > 1000) {
  83                                         //printf("BOOM! %d\n", (int)buf[j]);
  84                                         //puts("");
  85                                         putchar('!');
  86                                         fflush(stdout);
  87                                         break;
  88                                 }
  89                         }
  90                 }
  91
  92                 snd_pcm_close (capture_handle);
  93                 exit (0);
  94         }