The subject says it all.  I can not seem to get CDIOCPLAYTRACKS to
actually start playing an audio cd.  CDIOCPLAYBLOCKS works fine though
I have yet to find a way to determine the number of tracks on the disk.

  The error that is returned by perror() is "Invalid Argument".  The
error that is sent to the console is:
cd6(aha0:2:6): illegal request. data = 00 00 00 00 20 00 00 00 00 00

  Perhaps there is something more that needs to be done before using
CDIOCPLAYTRACKS.  Here is the code in question:

#include <sys/ioctl.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/cdio.h>

int
main(void) {
  char *device="/dev/cd6a";
  int fd;

  if( (fd=open(device, O_RDONLY)) == -1) {
    perror("open");
    exit(EXIT_FAILURE);
  }
  
  {
    struct ioc_toc_header th;

    if( ioctl(fd, CDIOREADTOCHEADER, &th) == -1) {
      perror("ioctl(CDIOREADTOCHEADER)");
      exit(EXIT_FAILURE);
    }

    printf("start: %d end: %d len: %d\n", th.starting_track, th.ending_track, th.len);
  }

  {
    struct ioc_play_track pt;

    pt.start_track=1;
    pt.start_index=1;
    pt.end_track=2;
    pt.end_index=1;

    if( ioctl(fd, CDIOCPLAYTRACKS, &pt) == -1) {
      perror("ioctl(CDIOCPLAYTRACKS)");
    }
  }

  {
    struct ioc_play_blocks pb;

    pb.blk=1;
    pb.len=100000;

    if( ioctl(fd, CDIOCPLAYBLOCKS, &pb) == -1) {
      perror("ioctl(CDIOCPLAYBLOCKS)");
    }
  }

  /*
  if( ioctl(fd, CDIOCALLOW) == -1) {
    perror("ioctl(CDIOCALLOW)");
    exit(EXIT_FAILURE);
  }

  if( ioctl(fd, CDIOCEJECT) == -1) {
    perror("ioctl");
    exit(EXIT_FAILURE);
  }
  */
  
  close(fd);

  return 0;
}


  

---
Kent Vander Velden
graphix@iastate.edu