Additional sign bit hiding of transform coefficients in HEVC

Transform coefficients take up a significant portion of the transmitted bitstream generated by video codec. For every non-zero coefficient, the sign information is sent separately from the amplitude. According to the statistical patterns, the signs of the transform coefficients are rarely predictable, thus bypass mode is usually used in the following CABAC engine to encode the sign information. In H.265/HEVC, a novel multiple sign bits hiding (MSBH) technique is adopted to hide one sign for each selected CG. In this paper, we propose to further perform one additional sign bit hiding (ASBH) for the selected TBs while the MSBH can coexist. To verify the effectiveness of our proposed ASBH, we implemented it on the state-of-the-art HM9.0 test model of H.265/HEVC. Experimental results show that the proposed ASBH always outperforms the anchor for all tested sequences with very trivial complexity added at the decoder side.