1. A video-processing device comprising: a processor; a memory device; and computer instructions stored within the memory device that control the processor to: determine a motion vector for a macroblock of a frame of video based on a function of the macroblock and reference macroblocks of the frame; determine, based on information available to an encoder of the video and a decoder of the video, a segmentation map that partitions the macroblock into a plurality of segments along one or more q-pel resolution boundaries of the segments, wherein each of the segments represents an object in the frame of video; determine a plurality of segmented-block motion vectors for the macroblock based on the segmentation map; and encode the macroblock using the segmented-block motion vectors.