Improved mode decision algorithm based on residues and early zero block detection in H.264/AVC - Springer

摘要

Video compression standard H.264/AVC outperforms previous standards in terms of coding efficiency but at the cost of higher computational complexity. In H.264/AVC, the variable block size full motion estimation is the most time-consuming operation. This paper presents a method to reduce the complexity of motion estimation in two stages. The first stage exploits the similarities between frames for early SKIP mode decision for a macroblock (MB) based upon a criteria formulated on the basis of the statistics of the frame difference residues. MBs that fail to qualify for the SKIP mode in the first stage spills over to the second stage where mode decision depends upon the number of zero blocks (ZB) in the MB. The study of the full search motion estimation on different sequences show that there is a strong dependence between the number of ZBs in a MB and the likelihood of a particular mode being selected. The proposed algorithm utilizes this relationship for early mode decision for a MB. The algorithm is evaluated using a wide range of test sequences from different classes. Experimental results show that the proposed algorithm gives considerable saving in encoding time and search points in the range of 36–87%. Furthermore, despite the reduction in computational complexity, the coding efficiency (picture quality and bitrate) in the proposed method is comparable to the H.264/AVC standard software Joint Model (JM12.4).