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 inter-frame encoded frame: a) decoding the motion vectors of the frame; b) selecting N sets of the motion vectors, wherein N is an integer value greater than 1; c) calculating a motion estimation for each set; d) calculating a median squared error value for each motion estimation; and e) selecting the motion estimation with the least median squared error value as that representative of the global motion of the frame with respect to a preceding or succeeding anchor frame.