[MPlayer-users] Converting 512:272 to 480:480 with aspect=4/3?

[Svante Signell]

Need advise hoe to expand/scale/crop an avi clip of size 512x272 to an
mpeg2(SVCD) clip of size 480:480 expanded to 640:480 when displayed.

-vf expand=480:480 aspect=4/3 -ovc lavc -lavcopts
vcodec=mpeg2video:aspect=4/3
gives an image of size 512:480 scaled to 640:480 when displayed, i.e.
the aspect ratio is not correct (compressed faces)

-vf expand=480:480,scale=640:480:aspect=4/3 -ovc lavc -lavcopts
vcodec=mpeg2video:aspect=4/3 which should be somewhat correct I believe
but this just gives a flickering image.

Putting scale before expand gives images displayable but with an aspect
ratio wrong in the other direction (long faces).

The problem is: 
Expand=480:480
==============
x: 512->480 = shrink: expand does not scale down, 512 is kept.
y: 272->480 = expand: OK
The resulting image is of size 512:480->640:480 when displayed, i.e.
aspect ratio is wrong.

Scale=480:480
=============
x: 512->480 = shrink
y: 272->480 = expand
The result is that the aspect ratio is destroyed.

Expand=640:480 and scale=640:480 also gives wrong results since the
aspect ratio comes into play then displayed.
 
Transcode handles this situation differently. How to do this correctly
with mplayer and mencoder?