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

wm4 nfxjfg at googlemail.com
Tue Sep 24 11:18:28 CEST 2013

On Tue, 24 Sep 2013 13:09:12 +0400
Vladimir Mosgalin <mosgalin at VM10124.spb.edu> wrote:

> Hi Reimar Döffinger!
>  On 2013.09.24 at 09:43:53 +0200, Reimar Döffinger wrote next:
> > >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.
> > 
> > 1.ass and 2.ass are supposed to look exactly the same.
> > I see exactly two possibilities:
> > 1) (likely) I misunderstood how line-drawing clipping is supposed to work. The way 2.ass and mpv render is just wrong, and the reason for the performance difference.
> > 2) libass implements the line drawing clipping wrongly. That should mean that mpv uses a different fork of libass than the one you tried with MPlayer.

First, try to get libass git. There have been changes which affect blur
and similar things. Use http://code.google.com/p/libass/source/checkout

The latest release is almost a year old now. We probably should make a
new one.

> Let's see, are we even seeing the same thing?
> Here is how 1.ass looks in mplayer:
> http://lime.hacked.jp/sub/mplayer-sub1.jpg
> Here is how it mostly looks in mpv:
> http://lime.hacked.jp/sub/mpv-sub1.jpg
> except for glitch that happens sometimes:
> http://lime.hacked.jp/sub/mpv-sub1-glitch.jpg
> As you can see, mplayer renders subtitle way too blurry. Is it really
> supposed to be like that?
> Here is how 2.ass looks in mplayer
> http://lime.hacked.jp/sub/mplayer-sub2.jpg
> and mpv
> http://lime.hacked.jp/sub/mpv-sub2.jpg
> (it's mplayer built with git libass, but 0.10.1 looked the same)
> There are more differences in rendering if using scale filter before ass
> rendering or in fullscreen, but I'm unable to take screenshots of
> either.. It was hard enough to take these screenshots as I had to do it
> quite roundabout way and they still came out glitchy often (empty
> windows, no subs, distortions, transparent subtitle parts replaced by
> checkers pattern and so on).

All that sounds like there aren't any issues in mplayer or mpv, just
that 1. different libass versions with different bugs (up to mplayer's
completely retarded builtin copy, which is slightly modified compared
to official libass, you should fix that), and 2. your OpenGL driver is
severely broken.

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