Fast overlapped block motion compensation with checkerboard block partitioning
The overlapped block motion compensation (OBMC) scheme provides an effective way to reduce blocking artifacts in video coding. However, in comparison with the traditional block motion compensation (BMC), its complexity of motion estimation increases significantly due to the interdependency of motion vectors. In this work, a new fast motion estimation algorithm is proposed for OBMC based on the checkerboard block partitioning and grouping in encoding. This algorithm, called the grouped OBMC (GOBMC), effectively decorrelates dependency among OBMC motion vectors and facilitates the search process. In comparison with traditional iterative OBMC motion search, GOBMC performs motion estimation only once per macroblock at the encoder, and reaches a local optimal solution with degradation of 0.05-0.1 dB. At the decoding end, we also propose a fast OBMC reconstruction scheme which reduces the complexity of multiplication to 38% of that of traditional OBMC reconstruction while preserving the same visual quality as obtained via BMC search with OBMC reconstruction.