* - seekable (if you can seek, it doesn't say if 'bar display' has be shown
* or not, for that check position != 0.0)
* - can-pause
+ * - teletext-es to get the index of spu track that is teletext --1 if no teletext)
* * For intf callback upon changes
* - intf-change
* - rate-change for when playback rate changes