A novel macro-block group based AVS coding scheme for many-core processor

Implementation of video coding systems such as H.264/AVC and AVS on multi-core and many-core platforms is attracting much attention. The slice-level parallelism is popular in parallel video coding for its simplicity and flexibility, however, the video quality loses greatly since the partitioning of slices breaks the dependency between macro-blocks, especially on multi-core or many-core platforms. To address this problem, we propose a Macro-Block Group (MBG) parallel scheme for parallel AVS coding. In the proposed scheme, video frames are equally divided into rectangular MBG regions; each MBG consists of more rows and less columns of macro-blocks than the slice-level scheme. Given that MBG is not syntactically supported by AVS, a vertical partitioning scheme is introduced. Additionally, we use mode confining and motion vector difference adjusting techniques to keep consistent with the standard. Two MBG parallel schemes (5×9 MBG partition and 8×7 MBG partition) are developed on a TILE64 manycore platform, where P/B frames use the MBG parallel scheme and I frames use the macro-block-level parallelism. Experimental results show that the proposed scheme of 5×9 MBG partition can achieve a reduction of 52% (IPPP) and 41% (IBBP) quality loss while keeping the same speed-up compared with the slice-level parallelism. With more cores employed, the scheme of 8×7 MBG partition gains 23.9 times of speed-up compared with the single-core implementation and achieves similar coding performance as the 5×9 scheme.