[MPlayer-users] ssa/ass rendering uses lots of cpu with -vo gl

Vladimir Mosgalin mosgalin at VM10124.spb.edu
Mon May 2 01:01:58 CEST 2011

Hi Reimar Döffinger!

 On 2011.05.01 at 22:50:26 +0200, Reimar Döffinger wrote next:

> On 1 May 2011, at 22:30, Vladimir Mosgalin <mosgalin at VM10124.spb.edu> wrote:
> >> Hm, could you please run with -aspect set to your monitor's aspect so
> >> that fullscreen has no black borders?
> >> It looks like the driver spends a lot of time allocating memory, which can
> >> happen once the subtitles get too large and that bit of extra space might
> >> make the difference. I guess nobody optimised allocating memory for textures.
> > 
> > o.O there seem to be no problems if -aspect 4/3 is added.
> > 
> > perf reports in fullscreen seem to be close to window mode now.
> > 
> > So, hm, I must add expand filter to everything to fix this?.. or there
> > is some other solution?
> Does expand avoid it also? Does it look exactly the same? As playing normally?

Well, I suggested expand filter at random when writing that mail, now I
checked how it works. This seems a bit complicated.

There are few ways of using expand, from what I can see. One is
specifying exact dimensions. Another is specifying one dimension and
letting it autoguess the other. Another way is to use only last, aspect
option of expand.

Neither of these does satisfactory subtitle rendering, they are out of
image - which is bad, because some subtitles are supposed to be on
video, or they look very bad - either render in wrong spot, or can't be
seen because they use borders and colors that make them look very ugly
or being unreadable on black borders. Many people design ssa subtitles
in such way so they look good only when they're on video..

As for slowness, this is confusing. Aspect way of using expand,
-vf-add expand=:::::4/3 has exact slowness as when not using expand at
all, despite subtitles being rendering partially on video and partially
on black border.

Same for -vf-add expand=0:639::::, which looks the same, but calculates
first number automatically (or something), behaves exactly the same:
very slow.

But if I specify both dimensions, i.e. -vf-add expand=704:639:::: then
rendered video, once again, looks the same, but it works fast and
without problems. But of course, this very last way of using expand
can't be written in config and such :-/



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