[MPlayer-users] probably my usual stupid question of the week

Loren Merritt lorenm at u.washington.edu
Fri Apr 16 21:51:15 CEST 2004

On Fri, 16 Apr 2004, Aaron Peterson wrote:

> > Rescaling is the only way that most players understand... If you want
> > to keep the original size you'll have to use insanely high bitrate
> > anyway.
> The only reason I would want to keep the original size is to have a nicer
> finished movie by preserving information.  If that requires an
> unreasonably high bitrate though to look nice, it sounds like you're
> saying I would perhaps get more of what I'm looking for by scaling down
> though.  I generally wouldn't want to go over two 700 M cds worth of
> finished video, and have been encoding original size at
> vbitrate=1200-1800.  These look fair, but still show some obvious defects.
>  Especially when there's lots of movement with lots of varied color.  I'll
> have to experiment and see what I see.  What is an insanely high bitrate
> by your definition?  I watch these movies mostly on a 30" widescreen tv.
> That seemed relevant for some reason.
> On a related note, I've been using -ovc frameno (and deleting the
> resulting file) just to find out what bitrate mencoder thinks I can encode
> and stay under the 700M limit.  If I scale down, I assume this will result
> in a smaller video file.  Can I use -vf crop=blah,scale=blah with -ovc
> frameno to make it take those things into account?
> Aaron

Bitrate is bits per time. It depends only on total movie length and total
file size, not on resolution or video filters.
Scaling down will produce a smaller file only if you encode at constant
quantizer. If you use 2-pass or abr, then it will affect quality but not

--Loren Merritt

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