[MPlayer-users] encode to dvd useing nicos patch produce null size mpeg file!

Matthew W. Miller mwmiller at columbus.rr.com
Sat Dec 11 00:49:28 CET 2004

On Fri, Dec 10, 2004 at 04:53:12PM +0100, Heine Laursen wrote:
>Giacomo Comes wrote:
>>adding -vf scale=702:576,expand=720:576 to mencoder will do the job.
>Well that's basicley what I don't undarstand! How can the aspect be
>1.33 when it's not 1.33? I'm confused :-(

You're confused because you're assuming pixels in a DVD image are
square. :) They're not, due to limitations in television hardware.  In
PAL Land, the pixels are slightly wider than they are tall (so the image
is fewer pixels wide than you'd expect).

702x576 of a PAL DVD image is stretched horizontally to a 4:3 aspect
ratio.  Getting it to that crucial size is what the 'scale' part of
Giacomo Comes's suggested command line does.
	There's a little extra width, (a.) to give some leeway for dubs
from analogue videotape, and (b.) to simplify MPEG compression by
getting both dimensions to multiples of 16; so the total image is
720x576.  That's what the 'expand' part accomplishes.

For excruciating levels of detail on this matter, see
http://www.iki.fi/znark/video/conversion/  (which has been referred to
on this list a few times before).
Matthew Miller <mwmiller at columbus.rr.com>
"One of the best things about the internet is finding out how wholesome
you really are compared to the other freaks out there." --Anthony Myers

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