Hardware oriented category pre-determination algorithm for SAO in HEVC

High efficiency video coding (HEVC) is a video compression standard that outperforms the predecessor H.264/AVC by doubling the compression efficiency. To enhance the coding accuracy, HEVC adopts sample adaptive offset (SAO) which classifies reconstructed pixels into different categories. During the pixel classification, however, SAO cannot use the raw samples in the current code-tree-block (CTB) boundary 4 × 4-blocks because these pixels need to be processed by deblocking filter first, which poses the problem for hardware design. This paper proposes hardware oriented category pre-determination algorithm which estimates the deblocking strengthens on CTB boundaries and selects the promising samples in these areas during SAO classification. Compared with HEVC test mode (HM12.0), experiment results illustrate that the proposed method achieves the average 0.1% BD-bitrate (BDBR) reduction, or equivalently 0.008 db PSNR increasing.