MicroDVD, SubRIP, SSA subtitle format should work...
 Options: --sub-file <subtitle file> [--sub-fps, --sub-delay --sub-format].

 * modules/demux/avi : make use of subtitle parser.
 * modules/demux/asf : display movie length. (It will not work with live
streams of course).

 modules/codec/spudec : use i_dts to send end of display time for subtitle.
(Yes it's ugly, but it works :)