Modifing mpeg2 aspect ratio ID

[deadk]

ok, unless i'm mistaken, or am not understanding something, i "think" (am not sure) that in an mpeg2 stream, the aspect ratio is a simple byte parameter, which can be modified without reencoding the video.
why i ask this, is i have a svcd, which was obviously encoded at 16:9 aspect ratio. Now this'll play fine on the pc, but on a standalone, it'll not have the original aspect ratio. (It plays FS on a standalone & windvd, while normal WS under wmp)

i've tried everything, to try and change the aspect ratio "id" to 4:3 without success.

I was told to try vstrip with the parameter:
vstrip original.vob -a2 -o newpropervideo.vob

now, i tested this on a vob, and it worked perfect (changing a normal WS video stream to FS)
but on an mpg file, it refuses to work
I always get:
"Encountered encrypted sector, attempting key recovery [@LBA 35]

* Unable to recover key"

does anyone know of a program or of which byte(s) need modification ?
(like in avi's, the index is after idx1xxxx, this could be after a specific parameter, or always on the same hex position.. ?)

any help would be appriciated.
hope this is the right forum for this question too.

[disturbed1]

This utility change can the parameters of mpeg headers.

http://www.offeryn.de/avestensione.htm

[deadk]

thx alot :)
that's all i needed