[MPlayer-dev-eng] Some libass bugs

[Vladimir Mosgalin]

Hi Compn!

 On 2007.05.23 at 12:34:50 -0400, Compn wrote next:

> >Also subtitle positioning keys (r and t) are not functional when -ass
> >is in use.
> 
> not sure if they are supposed to work with libass...

Well why not? At least with ass = 1 in config, when libass is used to
rendering plain srt subtitles which have no position information anyway.
Right now this feature is lost.

Actually, I think it might be implemented even for subtitles which
specify position. For them, "subtitle position" value should work as
vertical screen size in percents, i.e. when it's set to 90 and your
screen's height is 1200 subtitles are rendered as if screen height is
1080, from the top of the screen, but not to the very bottom.

> also sub_step works for stepping back, but not forward.
> sub_delay does weird things too :)

sub_step works either way, but in mkv subtitles which are in the future
haven't been extracted yet, so you obviously can't go forward - libass
simply doesn't know about these subtitles. With external subtitle file
or after you've seeked backwards you should be able to go forward.

However, sub_step has some very obscure bug, some subtitles can "fall
out" and completely ignore sub_step command, i.e. when you do sub_step
-1 you go two subtitles back, and when you do sub_step +1 after that you
go two subtitles forward, and subtitle in the middle only renders
regular way, there is no way to recall it with sub_step.

-- 

Vladimir