I have some video from my camera shot in 16x9 mode. Somewheres along the line in processing, the 16x9 flag is gone, and everything thinks it's 4x3 when it's not. In either the .avi file, or the .mpv file, how do I go about resetting the 16x9 flag so the file is interpreted correctly? I shouldn't be hard, but at present, it is eluding me.

Thanks in advance for your tips