Compound Block algorithm of moving object and background in H.264

H.264 is the newest video encoding algorithm introduced by ITU, which adopts block matching algorithm(BMA) and supports multiple reference frame. If video sequences only have single moving object and background pictures, using BMA may lead to prediction error and even decreased coding efficiency. And in the object based coding, additional bits for encoding the shape of the objects are required and syntax of H.264 is also needed to improve. In this paper, a compound block algorithm of moving object and background(CBA) is proposed. Firstly each block is regarded as a composition of a background plane and a moving object plane, and the two plane are predicted respectively. Secondly, the boundary separating the two parts is predicted from boundary in the previous decoded frame and the best vector is selected out by a boundary estimation algorithm. Finally, the prediction errors of the two parts are transmitted by transform, quantization and binary coding, and no additional bits are required. The experimental result show that the PSNR is enhanced by 0.2̃0.9db.