1. A motion estimation method for a succession of frames in a digital coding system, comprising: a) with reference to a first block in a first frame, searching within at least a portion of a second frame for a second block that corresponds to the first block; and b) estimating a motion vector of the first block with respect to the second block in at least the portion of the second frame; wherein, in step a), all blocks in the second frame are searched according to a distance-weighted search sequence starting from a candidate origin block.