Joint position and amplitude coding in hybrid variable length coding for video compression

Hybrid variable length coding (HVLC) was recently proposed as a novel entropy coding scheme for block-based image and video compression, which divides each transform block into low frequency (LF) region and high frequency (HF) region and codes them differently. To efficiently code LF region, a two-dimensional position and one-dimensional amplitude coding scheme (2DP1DA) was also proposed, which jointly codes the 2D position information, i.e., run of consecutive zero-valued coefficients and run of consecutive nonzero coefficients. To further explore the potential of HVLC concept, we propose a new scheme for coding LF region, which codes the 2D position and amplitude information of each nonzero cluster jointly with manageable complexity. The experimental results show that compared with CAVLC in H.264, about 3.5% bit rate reduction is achieved by the proposed method for a wide range of quantization parameters (QP).