A Hybrid Coded Block Patterns Based Fast Mode Decision in H.264/AVC

The video coding standard H.264/AVC although possesses the advantage of higher coding efficiency compared to previous ones, it would result in a high computational complexity due to various block sizes motion estimation for multi-modes decision. In this paper, a hybrid inter-mode decision algorithm is presented, combining coded block pattern (CBP) with motion activity and Rate-Distortion (RD) cost. In this algorithm, CBP and CBP_4×4, which indicate none-zero coefficient block, is used to determine candidate modes at macroblock level and sub-macroblock level. Further, the normalized motion activity is used to identify the homogeneity of the block and target the candidate modes set more accurate. An early termination is also made between macroblock level and sub-macroblock level by RD cost comparing. The experimental results show that the proposed algorithm achieves approximately 60% of computational complexity saving in terms of encoding time, while with negligible quality degradation, compared to the conventional method in H.264/AVC.