1. A method for determining a motion vector describing motion relative to a reference block, the method comprising: determining which of a plurality of prediction blocks is a good match with the reference block, according to a match criteria; performing a local area exhaustive search to produce a best match with the reference block, the search performed in an area centered around the good match prediction block, the best match having integral pixel resolution; modeling the degree of match between the best match and the reference block as a quadratic surface; analytically determining a minima of the quadratic surface, the minima corresponding to a best matching block with fractional resolution; and computing a fractional motion vector based on the best matching block with fractional resolution.