[vdr] HDTV -> mpeg4

Jukka Tastula jukka.tastula at kotinet.com
Mon Mar 28 17:02:18 CEST 2005


On Monday 28 March 2005 15:25, Grégoire Favre wrote:

> just done a small try to convert an Euro1080 FTA preview to mpeg4, with
> a bitrate of 2500 with mencoder : quality was very bad...

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

> Anyone already converted (and keeping the resolution) HDTV with a
> perfect quality to mpeg4 ?

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.



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