[scharfis_brain]

GMC = Global Motion Compensation:

depan searches for the larges moving object within the video
then depan moves the prev. and next frames, so the object of the current frame is overlaid exactly.

'normal' motion compensation is not moving thewhole frame, it either moves blocks of defined size to synthetisize a new frame or it is warping the frame as if it would be as flexible as a rubber...