There does indeed seem to be a problem in the way the Aspect Ratio is calculated. I have a number of widescreen files that, for example, have a size of 720 pixels (width) by 576 pixels (height).
The Aspect Ratio has simply been calculated by the formula 720/576 which gives 1.25, indicating a 4:3 format !! This is what is shown in the NFO file.
When I view the details in the very useful MediaInfo tool, it also shows the same width/height properties, but more importantly it does have a property called "Display Aspect Ratio" which correctly shows 16/9 (or 2.35 depending on the widescreen format).
It would seem Media Companion needs to retrieve this porperty from the file rather than just dividing the pixels as it currently does.
I'm going to attempt to write a utility (using the MediaInfo.dll file) that extract the correct information and updates the NFO file. Would be great if Media Companion can do this automatcally though.
If I have any luck, I'll post back but don't hold your breath !!