A motion estimator includes a shape, address and vector generator to produce control signals according to a selected size and shape of a search area comprising scan lines. A variable delay reads reference image data of a frame in which a matching macroblock is sought from a store under control of a variable delay control signal from the signal generator to align a current serial input stream of a current scan line with a serial input stream of an immediately preceding scan line. The aligned reference image pixel data is matched against pixel data of a current macroblock using a vector from the signal generator to produce a score representing a quality of the match. A best score together with the corresponding best vector is recorded and the best vector output.