Archive for April, 2011

Fixing the aspect ratio on Canon camcorder *.MOD files

Saturday, April 2nd, 2011

I have a Canon FS200 digital video camera which creates MOD files.  These are playable on Linux by simply changing the file extension to “mpg”.  The only issue is that the video displays in 4:3 aspect ratio, whereas it should be 16:9.

On many players, you can override the display aspect ratio during playback and then the files display correctly.  The problem is when you want to edit these files or create overlay text/graphics, as the editing program will process them in 4:3 ratio, and then when displayed in 16:9, the overlays will look stretched (while the video looks correct).

Although I have tried to solve this a number of ways, the actual fix is remarkably simple and fast.  The clue to this fix was in the error message “ODML: Aspect information not (yet?) available or unspecified, not writing vprp header.“.  Searching in the mencoder man page for “vprp” provided the solution.  Mencoder has a command line option “-force-avi-aspect” that can be used with the “-ovc copy” option, so you don’t need to re-encode (and potentially loose quality).  As this is only updating the meta data in the file, the fix is almost instantaneous.

The following command will perform the fix:

mencoder -oac copy -ovc copy -force-avi-aspect 1.777 input-4_3.mpg -o output-16_9.mpg