Fast sample adaptive offset for H.265/HEVC based on temporal dependency

The newly introduced in-loop filter in H.265/HEVC, i.e., sample adaptive offset (SAO), can effectively improve the coding efficiency as well as the subjective quality of encoded videos. However, complex operations are needed in the procedure of SAO which imposes challenges for real-time applications. In this paper, the temporal relationships of two SAO parameters between the temporal base layer and higher temporal layers are explored and utilized to propose a fast SAO method for reducing the computational complexity. Experimental results show that, compared to the original SAO implementation in the reference software model of H.265/HEVC, i.e., HM13.0, the proposed fast SAO method achieves an average of 72.28% reduction in SAO processing time with the average BD-rate increment being 0.56% for LD-P, LD-B and RA configurations.