Cropping Using Mencoder

[Major_Kong]

What's your method when cropping with mencoder ? (let's assume -vf cropdetect, doesn't get it right)
Is there a better way than trial & error ?

[blaz]

For dvd's I only crop the wide-screen's 2.35:1 and there I use:
-vf crop=720:368:0:56
That should get everything and is divisible by 16.

I'm not worried about small black lines around the video, but just want to crop most of the large top/bottom black bands in the 2.35:1 dvd's