H.264/AVC improvement based on adaptive motion vector coding

We propose a new method for improving motion vector coding. The coding efficiency of the H.264/AVC standard is significantly degraded for video sequences that include irregular motions. The degradation is caused by the fact that the correlations among the motion vectors on adjacent blocks get to be small when motions are irregular. Our method solves this problem by two schemes. First, the predictive motion vector (PMV) is adaptively coded with additional bits based on the distribution pattern of reference vectors. Second, an appropriate code table for the motion vector difference (MVD) is adaptively selected out of a couple of tables defined in advance. These schemes enable the appropriate methodologies for the motion vector coding to be adaptively selected according to the motion vector diversity. Experimental results show the effectiveness and potentiality of our approach for high coding efficiency.