playcd.c

在linux下多媒体开发实例linux下多媒体开发

/*
 * playcd.c
 * Example of simple audio CD player.
 *
 */

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

/* display command usage and exit */
void usage(void)
{
  fprintf(stderr,
	  "usage: playcd <options>\n"
	  "valid options:\n"
	  "  play <first-track> <last-track>\n"
	  "  stop\n"
	  "  pause\n"
	  "  resume\n"
	  "  volume <left-vol> <right-vol>\n"
	  "  toc\n");
  exit(1);
}

/*
 * Utility routine to print error message and exit if given
 * non-zero status
 */
void status_check(int status, const char *ioctl)
{
  char buf[255];
  if (status != 0) {
    sprintf(buf, "%s ioctl failed", ioctl);
    perror(buf);
    exit(1);
  }
}

int main(int argc, char *argv[])
{
  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_ti ti;                 /* track/index info */
  struct cdrom_tochdr tochdr;         /* TOC header */
  struct cdrom_tocentry tocentry;     /* TOC entry */
  struct cdrom_volctrl volctrl;       /* volume settings */

  /* there should be at least one command line argument */
  if (argc < 2)
    usage();
  /* open device */  
  status = fd = open(device, O_RDONLY);
  if (status < 0) {
    perror("open failed");
    exit(1);
  }
  if (!strcmp(argv[1], "play")) {
    if (argc != 4)
      usage();
    ti.cdti_trk0 = strtol(argv[2], 0, 10);
    ti.cdti_ind0 = 0;
    ti.cdti_trk1 = strtol(argv[3], 0, 10);
    ti.cdti_ind1 = 0;
    status = ioctl(fd, CDROMPLAYTRKIND, &ti);
    status_check(status, "CDROMPLAYTRKIND");
  } else if (!strcmp(argv[1], "stop")) {
    status = ioctl(fd, CDROMSTOP);
    status_check(status, "CDROMSTOP");
  } else if (!strcmp(argv[1], "pause")) {
    status = ioctl(fd, CDROMPAUSE);
    status_check(status, "CDROMPAUSE");
  } else if (!strcmp(argv[1], "resume")) {
    status = ioctl(fd, CDROMRESUME);
    status_check(status, "CDROMRESUME");
  } else if (!strcmp(argv[1], "volume")) {
    if (argc != 4)
      usage();
    volctrl.channel0 = strtol(argv[2], 0, 0);
    volctrl.channel1 = strtol(argv[3], 0, 0);
    volctrl.channel2 = 0;
    volctrl.channel3 = 0;
    status = ioctl(fd, CDROMVOLCTRL, &volctrl);
    status_check(status, "CDROMVOLCTRL");
  } else if (!strcmp(argv[1], "toc")) {
    int track;
    status = ioctl(fd, CDROMREADTOCHDR, &tochdr);
    status_check(status, "CDROMREADTOCHDR");
    printf("Track mn/sc/frm   Track mn/sc/frm   Track mn/sc/frm   Track mn/sc/frm\n");
    for (track = 1 ; track <= tochdr.cdth_trk1 ; track++) {
      tocentry.cdte_track = track;
      tocentry.cdte_format = CDROM_MSF; /* want info in MSF format */
      status = ioctl(fd, CDROMREADTOCENTRY, &tocentry);
      status_check(status, "CDROMREADTOCENTRY");
      printf("%5d %02d:%02d.%03d %c ",
	     tocentry.cdte_track,
	     tocentry.cdte_addr.msf.minute,
	     tocentry.cdte_addr.msf.second,
	     tocentry.cdte_addr.msf.frame,
	     (tocentry.cdte_ctrl & CDROM_DATA_TRACK) ? 'D' : 'A');
      if ((track % 4) == 0 || (track == tochdr.cdth_trk1))
	printf("\n");
    }
    /* now print info for end of last track */
    tocentry.cdte_track = CDROM_LEADOUT;
    status = ioctl(fd, CDROMREADTOCENTRY, &tocentry);
    status_check(status, "CDROMREADTOCENTRY");
    printf("(end) %02d:%02d.%03d\n",
	   tocentry.cdte_addr.msf.minute,
	   tocentry.cdte_addr.msf.second,
	   tocentry.cdte_addr.msf.frame);
  } else {
    usage();
  }

  /* close device */
  status = close(fd);
  if (status != 0) {
    perror("close failed");
    exit(1);
  }
  exit(0);
}