1. A fast-search adaptive motion accuracy search method for estimating motion vectors in motion-compensated video coding by finding a best motion vector for a macroblock, said method comprising the steps of: (a) searching a first set of motion vector candidates in a grid of sub-pixel resolution of a predetermined square radius centered on V 1 , to find a best motion vector V 2 using a first criteria; (b) searching a second set of motion vector candidates in a grid of sub-pixel resolution of a predetermined square radius centered on V 2 to find a best motion vector V 3 using a second criteria; (c) searching a third set of motion vector candidates in a grid of sub-pixel resolution of a predetermined square radius centered on V 3 to find said best motion vector of said macroblock using a third criteria, and (d) wherein at least one of said first criteria, said second criteria, and said third criteria is a rate-distortion criteria.