Complexity reduction for overlapped block motion compensation (OBMC)

A novel idea to reduce OBMC search complexity based on checkerboard block grouping is proposed in this work. We call the proposed new scheme GOBMC (Grouped OBMC). No iteration is required in the proposed scheme for encoding, since the obtained OBMC motion vector set nearly reaches a local optimal solution in one iteration step and, therefore, the complexity is significantly reduced. The distortion measures, both in terms of PSNR and visual quality, remain about the same as those obtained from iterative OBMC motion search. In decoding, we propose an OBMC reconstruction which reduces the complexity of multiplication by a factor of 38% while preserving the visual quality as obtained from BMC search with OBMC reconstruction.