Global-local correlation-based early large-size mode decision for multiview video coding

Abstract. Multiview video coding (MVC) is a recent extension of H.264/AVC, and it consumes huge encoding time to select the optimal macroblock (MB) mode, among different size candidate modes. As compared with the small-size mode (Inter16×8, Inter8×16, Inter8×8, Intra8×8, and Intra4×4), the large-size mode (Skip/Direct, Inter16×16, and Intra16×16) occupies most of the MB mode proportion with much less computational complexity. Thus, if the large-size mode could be early decided as the optimal MB mode, the complexity of mode decision could be effectively reduced. In this work, an early large-size mode decision algorithm is proposed based on the global correlation of rate-distortion (RD) costs between neighbor views and the local correlation of RD costs among candidate modes. Average RD costs of large-size and small-size MB modes in the neighbor view are employed as a global reference for the threshold of early decision. And RD costs of estimated modes are used to calculate the local adjustment for the threshold. Experimental results demonstrate that the proposed algorithm can significantly reduce the whole encoding time while maintaining an RD performance similar to that of the original MVC encoder.