Reconfigurable hardware-friendly CU-group based merge/skip mode for high efficient video coding

Merge/skip mode is one of the most important inter prediction tools adopted in the High Efficiency Video Coding (HEVC) standard which is the state-of-the-art video coding standard. It is very efficient in reducing the side information for the blocks within the same object. However, it is difficult for parallel encoding and decoding due to the data dependency problem between neighboring prediction units (PU). Furthermore, different shapes and positions of PUs would result in different definition of the merge/skip candidate list (MCL), which would lead to potentially extra hardware cost and is not easy to be efficiently implemented by the hardware. To deal with this problem, two reconfigurable hardware-friendly MCL construction schemes are proposed in this paper. The first scheme which is called unified MCL (UMCL) uses one candidate list for all PUs inside the motion estimation region (MER), which is regarded as the basic parallel processing unit for the hardware realization. The second scheme which is named boundary MCL (BMCL) allows different candidate lists for the PUs on the boundary of MER. Both of the two schemes can have flexible parallel degree based on the requirement specification. Experimental results show that UMCL reduces the hardware complexity significantly with little coding performance degradation and BMCL achieves significant coding gain while maintaining the hardware complexity.