[MEncoder-users] Fwd: Questions on Mencoder performace

[Phil Ehrens]

larrystotler at netscape.net wrote:
> >-----Original Message-----
> >From: Phil Ehrens <phil at slug.org>
> 
> >None of these things will give you as big a performance boost as
> >switching from xvid to lavc will. Using '-oac copy' will also give
> >you a performance (and quality) boost. Good starting options for
> >lavc:
> 
> >-lavcopts vcodec=mpeg4:nr=1000:mbd=2:v4mv:trell:vpass=N:vbitrate=1800
> 
> >You will want to look into the docs for using cropdetect as well.
> 
> How well does lavc work on slower machines?  When you get right down to 
> it, it has to play on a slower machine, so if faster re-encoiding 
> results in a file that won't work as well on a slower machine, then 
> I'll stick with slower encoding.  I also usually look for wide screen 
> since I use them with a projector as well.

lavc mpeg4 works exactly as well as xvid on slower machines. Only h264
will really kill you on a slower machine (It seems to use about 10x as
much cpu when viewing with mplayer).

> As for '-oac copy' that just copies the MP2 audio.  That would make the 
> file size larger than using MP3,correct?  Will that work better on a 
> slower system?

It will make no difference, AFAIK. The size for mp2 will be the
same as for CBR mp3 at the same bitrate. I think I remember being
able to watch video on my P266 laptop with only a few dropped frames.

> A friend has a P4 Xeon 2.8Ghz, and he gets around 50 first pass and 
> 25-30 second pass.  That's why I am wondering.  We haven't been able to 
> check since his system is a Xeon and mine isn't....

Those are the kinds of numbers I would expect to see with lavc.