subchnl.c

在linux下多媒体开发实例linux下多媒体开发

/*
 * subchnl.c
 * Example program to display audio CD subchannel data
 */

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <linux/cdrom.h>

/* return audio status as a string */
char *audiostatus(int status)
{
  switch (status) {
  case CDROM_AUDIO_INVALID:   return "Invalid";
  case CDROM_AUDIO_PLAY:      return "Playing";
  case CDROM_AUDIO_PAUSED:    return "Paused";
  case CDROM_AUDIO_COMPLETED: return "Completed";
  case CDROM_AUDIO_ERROR:     return "Error";
  case CDROM_AUDIO_NO_STATUS: return "Stopped";
  default:                    return "Unknown";
  }
}

int main()
{
  const char *device = "/dev/cdrom";  /* CD-ROM device file name */
  int fd;                             /* CD-ROM file descriptor */
  int status;                         /* hold status of system calls */
  struct cdrom_subchnl subchnl;       /* parameter for ioctl call */

  /* open device */  
  status = fd = open(device, O_RDONLY);
  if (status < 0) {
    perror("open failed");
    exit(1);
  }

  while (1) {
    /* read subchannel data */
    subchnl.cdsc_format = CDROM_MSF; /* want results in MSF format */
    status = ioctl(fd, CDROMSUBCHNL, &subchnl);
    if (status < 0) {
      perror("CDROMSUBCHNL ioctl failed");
      exit(1);
    }
    printf("Status: %s Track: %d Position: %02d:%02d:%02d (%02d:%02d:%02d)\r",
	   audiostatus(subchnl.cdsc_audiostatus),
	   subchnl.cdsc_trk,
	   subchnl.cdsc_reladdr.msf.minute,
	   subchnl.cdsc_reladdr.msf.second,
	   subchnl.cdsc_reladdr.msf.frame,
	   subchnl.cdsc_absaddr.msf.minute,
	   subchnl.cdsc_absaddr.msf.second,
	   subchnl.cdsc_absaddr.msf.frame);
    fflush(stdout);
    usleep(100000); /* delay 0.1 second */
  }
  exit(0);
}