[MPlayer-users] ass subtitles, vo gl and amd video

Vladimir Mosgalin mosgalin at VM10124.spb.edu
Tue Sep 24 00:15:19 CEST 2013

Hi Reimar Döffinger!

 On 2013.09.23 at 23:30:03 +0200, Reimar Döffinger wrote next:

> > It's not software scaling that makes it slow, it's -vf ass filter
> > itself:
> I don't think so. At least not directly.
> I think this is caused by libass (at least our old internal copy?)
> handling \clip commands based on vector drawing really badly.

Well, mpv build that I checked used (unreleased) git snapshot of libass,
and there have been tons of fixes in it since 0.10.1 release which
mplayer uses. This would explain different "bugs" when rendering 1.ass
in mpv and mplayer, idk about performance difference.

I don't see any kind of performance problems with 2.ass (or visual

> Assuming this reproducible with the latest libass version this probably
> should be a feature request.

I just tried updating mplayer's libass to latest git and rebuilt it with
--enable-ass-internal (mostly works, except for it doesn't pull libass's
fribidi dependence automatically so had to force extra header/lib) - it
has same performance problems as with 0.10.1 on 1.ass. So there is more
difference with mpv ass subtitles rendering than just libass version..

I don't know of a way to force vf_ass-like rendering on mpv, so I only
checked default rendering with -vo opengl-hq - no performance problems
at all, but subtitles look quite a bit sharper than in mplayer. Idk why,
but for some reason mplayer always renders subtitles in 1.ass blurry for
me (not the case with other subtitles and 2.ass), while mpv renders font
edges sharp, as they're (I think) supposed to be.



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