An Improved Run_before Coding for H.264 CAVLC

Jie JIA  Daeil YOON  Hae Kwang KIM  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E93-A   No.2   pp.561-564
Publication Date: 2010/02/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E93.A.561
Print ISSN: 0916-8508
Type of Manuscript: LETTER
Category: Coding Theory
video compression,  entropy coding,  H.264/AVC,  CAVLC,  run_before,  

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Context-based adaptive variable length coding (CAVLC) is an entropy coding scheme employed in H.264/AVC for transform coefficient compression. The CAVLC encodes levels of nonzero-valued coefficients. Then indicates their positions with run_before which is number of zeros preceding each nonzero coefficient in scan order. In H.264, the run_before is coded using lookup tables depending on number of zero-valued coefficients that have not been coded. This paper presents an improved run_before coding method which encodes run_before using tables taking both zero-valued and nonzero-valued coefficients into consideration. Simulation results report that the proposed method yields an average of 4.40% bit rate reduction for run_before coding over H.264 baseline profile with intra-only coding structure. It corresponds to 0.52% bit rate saving over total bit rate on average.