[MPlayer-users] Converting 512:272 to 480:480 with aspect=4/3?
svante.signell at telia.com
Thu Jan 15 23:54:32 CET 2004
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
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:
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.
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?
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