1. A method of global motion estimation between frames of a motion-compensated inter-frame encoded video sequence, each frame of the sequence having a plurality of motion vectors encoded therein relating the frame to a preceding and/or succeeding frame of the sequence, the method comprising, for a particular frame: a) determining a motion estimation representative of the global motion between the particular frame and its anchor frame on the basis of motion vectors therebetween; b) determining one or more further motion estimations representative of the global motion between the particular frame and its anchor frame at least partially on the basis of motion vectors between the particular frame and one or more preceding or succeeding other frames; and c) selecting one of the motion estimations which meets at least one predetermined criterion as being representative of the global motion of the frame.