[vdr] HDTV -> mpeg4

Grégoire Favre Gregoire.Favre at gmail.com
Mon Mar 28 17:12:30 CEST 2005

On Mon, Mar 28, 2005 at 05:02:18PM +0200, Jukka Tastula wrote:

> 2500 is barely enough for an svcd. You can't seriously expect that to be 
> enough for 10 times the pixels, can you?

I can't agree with you about this point, I use Q=1000 for pal resolution
of VDR reccordings (3 pass mencoder) with thoses options :

-vf crop=$2 -sws 2 -oac copy -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=$Q:trell:mv0:mbd=2:v4mv:qprd:cmp=10:subcmp=10:mbcmp=10:predia=2:dia=2:vpass=1:turbo

Doing the same with Q=2500 was not that bad on my source, but really not

> Perfect quality? 
> mencoder -oac copy -ovc lavc -lavcopts \
> vcodec=mpeg4:vqscale=2:keyint=1:autoaspect (:ilme:ildct ) input -o output
> That'll make a big file though, probably bigger than the original, but 
> it'll be pretty much as good as it can get. Of course it'll be worse than 
> the original, lossy compression and everything. You probably wont notice.
> ilme:ildct is probably a good idea if the source is interlaced.
> I'm not at all certain if mbd=2 and qns make any difference when encoding 
> with constant quantizer. Qns takes way too much time anyway at that 
> resolution so just forget about it.
> Obviously this isn't very useful. It'd be a much better idea to specify an 
> average bitrate and do a two or three pass encode. That way you can 
> control how big the output file gets. Mplayer docs describe the process 
> very well.

I never thought of anything else than 3 passes :-)
	Grégoire Favre
http://magma.epfl.ch/Gregoire.Favre mailto:Gregoire.Favre at gmail.com

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