[MPlayer-users] [bug report] ass subtitle render + vf expand

[Zongyao QU]

./mplayer
-vf expand=:::::1.6 
-font ~/Library/Fonts/msyh.ttf
-quiet 
-sub-fuzziness 1 -ass {the movie path}

the sub is a .srt, autoload.

I want to use "expand" to make the letterbox, 
so that subtitle will render in the black area, rather than in the movie frame.

but if ass is on, it seams that the old sub won't be cleared out, 
so that all passed the sub lines will leave on the black area, 
resulting a mess up in the black area.

if ass is off, it is all right.

Did I miss something? or it is a bug?