ERROR DETECTION USING A MAXIMUM DISTANCE AMONG FOUR BLOCK-MOTION-VECTORS IN A MACROBLOCK IN A CORRUPTED MPEG-4 BITSTREAM

Errors are detected in a motion-picture-experts group (MPEG) bitstream that has been corrupted by wireless transmission. Some 16×16 pixel macroblocks are divided into four smaller 8×8 blocks. A motion vector is encoded for each block. The Euclid distance is generated for each possible pair of the four motion vectors, and the maximum of these distances is compared to a threshold distance. When the maximum distance among the motion vectors in a macroblock exceeds the threshold, a bitstream error is signaled and error concealment is triggered. Since the four blocks within a macroblock usually stay close to each other in adjacent video frames, large jumps in the relative location of one block usually indicate a bitstream error. Squares of the distances can be generated and compared to reduce the computational load by eliminating square-root operations.