[MPlayer-dev-eng] [patch][rfc] screenshot. Aspect Ratio, problems

[ObsessiveMathsFreak]

> Message: 5
> Date: Fri, 26 Aug 2005 02:10:42 -0400
> From: Rich Felker <dalias at aerifal.cx>
>
> It will just make playback incredibly slow.. Otherwise no problem.
> Just use -vf scale,screenshot -zoom

This worked perfectly, also with the vo_png filter. I get it now. I 
think. Software scaling vs Hardware scaling or at least internal mplayer 
scaling vs scaling on output. I know nauzing.

For some reason the filter needs to be wrapped around two scale filters 
like so
-vf scale,screenshot,scale

I have no idea why.

> Message: 3
> Date: Fri, 26 Aug 2005 13:49:40 +0300
> From: Jan Knutar <jknutar at nic.fi>
> 
> Now a cool thing, which would also open up the doors for many other neat features
> at the same time, would be if MPlayer could reconfigure the vf filter pipeline in
> realtime, to insert scale,screenshot,scale only when needed.
> Even crazier, to have the frame-exact seek ability, so that one could do away with
> the one-frame latency for taking screenshots too :-) But then it'd probably end up
> being as slow as xine :(
> 
> Those two combined would require some major surgery to mplayer.c's main, the
> only person crazy enough to touch main(){} is Oded but we've so far been unsuccessful
> in forcing him to do it :)
> Maybe surgery is the wrong word, rewrite perhaps... It's all probably in the TODO/WISHLIST
> too...

I did try that using vf_add_before_vo in vf.c . It worked, sort of. 
Turns out the filter would only be inserted if there was at least one 
other filter in the chain for some reason.

This of course inserted the screenshot filter, but did not remove it 
after the screenshot was taken. I'm just wondering could this be done 
with a quick hack by getting the vf_screenshot filter to have its own 
pointer point to its 'next' filter pointer and then 'deallocating' the 
filter? Or could we be talking a serious internal train wreck here?

Ideally if there was a method to remove a filter, which could be called 
from within the filter itself. Search me. I just work here. Or rather, I 
don't.