[MPlayer-users] Mencoder doesn't create Index

[Nick]

Hi,

I've encoded several DVD's with the following command:

mencoder -dvd-device VIDEO_TS dvd://1 -aid 128 -oac copy -vf 
crop=x:x:x:x,scale=x:x -ovc xvid -xvidencopts 
pass=1:bitrate=9999:autoaspect -o "movie.avi"
mencoder -dvd-device VIDEO_TS dvd://1 -aid 128 -oac copy -vf 
crop=x:x:x:x,scale=x:x -ovc xvid -xvidencopts 
pass=2:bitrate=9999:autoaspect -o "movie.avi"

Almost every movie plays fine, exept for Hero and Fahrenheit 9/11 where 
it is impossible to seek in the avi file.
Mplayer displays the following output when I try to seek in one of the 
avi's:

Cannot seek in raw AVI streams. (Index required, try with the -idx switch.)

I tried the -idx switch but it's still impossible to seek. Can someone 
tell me why mencoder doesn't create an index while encoding certain movies?

Regards,
Nick