1. A method of generating motion vectors from a macroblock in a current field to a macroblock in a past field for inter-picture video compression in a motion picture having images of F.sub.1 and F.sub.2 parities, comprising the steps of: a. defining a macroblock in a parity field of the current picture; b. searching the preceding field of the same or opposite parity to find a first best match macroblock in said preceding field; c. forming a vector from the current macroblock in the current parity field to the first best match macroblock in said preceding field of the same or opposite parity; d. scaling the vector so formed in step c. so that the scaled vector refers to a dual prime macroblock in the opposite parity field with respect to the first best match macroblock which defines the center of a dual prime search window; e. taking the average of the first best match macroblock and a set of dual prime macroblock locations in the dual prime search window and searching to determine a best match dual prime macroblock; and f. forming a dual prime motion vector and differential motion vector (dmv) which point to both the first best match macroblock and the best match dual prime macroblock.