avimux aspect ration issues in WMP12

[Chris Whittenburg]

I'm using avimux to create a 1280x960 resolution avi file (mjpg codec)
which plays fine in vlc and quicktime.

If I play it in Windows Media Player 12 on a win7 machine, the image
has wrong aspect ratio-- it's horizontal is squished so that it is
very tall and skinny.

Is WMP12 assuming some wrong aspect ratio or pixel aspect ratio that I
can patch avimux to provide?

thanks,
chris