Using the Simple DirectMedia Layer API

• Opening a CD-ROM drive for use

You can find out how many CD-ROM drives are on the system with the SDL_CDNumDrives() function, and then pick which one to use with SDL_CDOpen().

The system default CD-ROM is always drive 0. The CD-ROM drive may be opened for use even if there is no disk in the drive.

You should use the SDL_CDStatus() function to determine the state of the drive. After you are done using the CD-ROM drive, close it with the SDL_CDClose() function.

{
    SDL_CD *cdrom;

    if ( SDL_CDNumDrives() > 0 ) {
        cdrom = SDL_CDOpen(0);
        if ( cdrom == NULL ) {
            fprintf(stderr, "Couldn't open default CD-ROM: %s\n" SDL_GetError());
            return;
        }

        ...

        SDL_CDClose(cdrom);
    }
}

• Playing the CD-ROM

CD-ROM drives specify time either in MSF format (mins/secs/frames) or directly in frames. A frame is a standard unit of time on the CD, corresponding to 1/75 of a second. SDL uses frames instead of the MSF format when specifying track lengths and offsets, but you can convert between them using the FRAMES_TO_MSF() and MSF_TO_FRAMES() macros.

SDL doesn't update the track information in the SDL_CD structure until you call SDL_CDStatus(), so you should always use SDL_CDStatus() to make sure there is a CD in the drive and determine what tracks are available before playing the CD. Note that track indexes start at 0 for the first track.

SDL has two functions for playing the CD-ROM. You can either play specific tracks on the CD using SDL_CDPlayTracks(), or you can play absolute frame offsets using SDL_CDPlay().

SDL doesn't provide automatic notification of CD insertion or play completion. To detect these conditions, you need to periodically poll the status of the drive with SDL_CDStatus(). Since this call reads the table of contents for the CD, it should not be called continuously in a tight loop.

void PlayTrack(SDL_CD *cdrom, int track)
{
    if ( CD_INDRIVE(SDL_CDStatus(cdrom)) ) {
        SDL_CDPlayTracks(cdrom, track, 0, track+1, 0);
    }
    while ( SDL_CDStatus(cdrom) == CD_PLAYING ) {
        SDL_Delay(1000);
    }
}