typedef struct{
  int id;
  CDstatus status;
  int numtracks;
  int cur_track;
  int cur_frame;
  SDL_CDtrack track[SDL_MAX_TRACKS+1];
} SDL_CD;| id | Private drive identifier | 
| status | Drive status | 
| numtracks | Number of tracks on the CD | 
| cur_track | Current track | 
| cur_frame | Current frame offset within the track | 
| track[SDL_MAX_TRACKS+1] | Array of track descriptions. (see SDL_CDtrack) | 
An SDL_CD structure is returned by SDL_CDOpen. It represents an opened CDROM device and stores information on the layout of the tracks on the disc.
A frame is the base data unit of a CD. CD_FPS frames is equal to 1 second of music. SDL provides two macros for converting between time and frames: FRAMES_TO_MSF(f, M,S,F) and MSF_TO_FRAMES.