1. A computer-implemented method for determining a motion vector describing motion relative to a reference block, the method comprising: determining, by a computer, which of a plurality of prediction blocks is a good match with the reference block, according to a match criteria; performing, by the computer, 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, by the computer, the degree of match between the best match and the reference block as a quadratic surface; analytically determining, by the computer, a minima of the quadratic surface, the minima corresponding to a best matching block with fractional resolution, wherein the analytically determining comprises: determining a first minima of the quadratic surface in a first direction; and determining a second minima of the quadratic surface in a second direction perpendicular to the first direction, wherein the second minima corresponds to a best matching block with fractional resolution; and computing, by the computer, a fractional motion vector based on the best matching block with fractional resolution.