[MPlayer-users] mencoder/crop => image distortion

[ROED,HAAVARD (HP-Norway,ex1)]

I'm encoding a DVD title:

[haavard at slugger blarg]$ mencoder -dvd 14 -v
[...]
VIDEO:  MPEG2  720x576  (aspect 3)  25.00 fps  8000.0 kbps (1000.0 kbyte/s)
[...]

using MEncoder 0.90rc5-3.2:

mencoder -dvd 14 -oac copy -ovc xvid -xvidencopts
pass=1:bitrate=1272:me_quality=5:4mv -vop crop=714:550:2:12 -o /dev/null
mencoder -dvd 14 -oac copy -ovc xvid -xvidencopts
pass=2:bitrate=1272:me_quality=5:4mv -vop crop=714:550:2:12 -o movie.avi

where the crop settings were detected with:

mencoder -dvd 14 -oac copy -ovc xvid -xvidencopts
bitrate=1272:me_quality=5:4mv -vop cropdetect -o /dev/null

This gives me a distorted video. (A staircase pattern of broad rows (bands),
some 5-6, of video shifted to the right which "rolls out" of the right edge,
reappearing on the left. In addition, there is an approx equal amount of
diagonal lines going across the encoded video from lower left to upper
right, at even distances across the whole video.)

1pass encoding the same DVD without cropping:

mencoder -dvd 14 -oac copy -ovc xvid -xvidencopts
bitrate=1272:me_quality=5:4mv -o movie.avi

gives a perfect result.

I'm guessing this is because the X crop value of 714 is not divisible by 16
(XViD restriction?), but since I can encode video where although X is
divisible by 16, and Y is NOT, I'm a tad confused.

How can I crop the image when the video apparantly has black borders on the
sides? Are the sides uncroppable (without rescaling)?.

The docs said something about aspect ratio correction, but thats only a
propriatary header parameter for MPlayer, and has nothing to do with the
encoding?

Exactly what are the dependancies and rules regarding cropping, rescaling
(*shudder*) and (XViD) video dimensions?

regards,
Haavard