VIDEO CODING APPARATUS AND VIDEO DECODING APPARATUS WITH AN IMPROVED MOTION VECTOR CODING METHOD

A motion picture coding and decoding apparatus divides each frame of a motion picture into a plurality of blocks and for providing a prediction error to each of the blocks between a target frame and a reference frame. A motion vector is coded for each block and stored for both the target frame and the reference frame. A differential motion vector is determined based upon the motion vector of the target frame and a corresponding block in the reference frame. The differential motion vector is then coded and multiplexed with the coded prediction error and output on a transmission path. The coded data is then decoded and the differential motion vector and a motion vector of a corresponding block from a reference frame can thereby be added to obtain a motion vector to be used for decoding the prediction error. Additionally, an error detection unit can detect the presence of an error in the coded differential motion vector, and a prevention unit can be used to prevent processing an erroneous differential motion vector, while an error amendment unit can substitute a motion vector of a predetermined block instead of the motion vector having the error.