[MPlayer-dev-eng] [PATCH] A new ASS renderer

[Reimar Döffinger]

On Wed, Sep 26, 2012 at 12:06:54PM +0200, Reimar Döffinger wrote:
> Vladimir Mosgalin <mosgalin at VM10124.spb.edu> wrote:
> >Hi Reimar Döffinger!
> >
> > On 2012.09.26 at 08:38:29 +0200, Reimar Döffinger wrote next:
> >
> >> >A silly question: is it possible/desirable to further increase
> >numbers
> >> >increased by glhack patch? Like, use 4096x4096 textures and increase
> >> >small
> >> >texture size.
> >> 
> >> Optimizing is quite useless without any way to get accurate
> >performance numbers.
> >> In particular, why does blur use over 6% CPU for gl rendering but
> >under 1% for vf _ass? I think your libass is broken and fails to do any
> >glyph caching with gl, possibly related to the margin stuff that only
> >gl offers by default.
> >
> >It does that only for fullscreen gl, not for window mode. Also it
> >doesn't do this for fullscreen if I use "expand=1920:1200" filter.
> 
> Yes, it does that exactly when the margin feature is used.
> 
> >It's normal libass 0.10.0, don't know what can be wrong with it..
> 
> At the very least it is not the included one I am using (but I do not remember whether I saw this with it or not).
> 
> >Anyhow you don't need to debug libass blur issues - there is example
> >where there is no karaoke, but fullscreen rendering still becomes very
> >flow, that is, gl-window-nokaraoke and gl-fullscreen-nokaraoke.
> 
> The blur is only the symptom, the cause is libass caching being broken which causes issues all the way down, probably including needlessly uploading new glyphs even though they have not changed.
> Or to put it differently: This is likely bad enough that any further debugging/benchmarking is useless until it is fixed.
> I think a way to estimate this is to use -vo gl:noaspect (which should be about the same as using expand).
> The real effect should be a bit worse than the performance difference this causes.
> You can also try if you can reproduce the performance issue using vf ass and the ass-margin settings.

Well, I found the issue, it is actually in MPlayer.