Adaptive Probability Updating of Look-Up Table Values for Encoding Coeff_Token
Jamil-Ur-Rehman, Ye Zhang · 2006
In the new H.264/AVC standard, when entropy coding mode is set to zero, residual block data is coded using a context adaptive variable length coding (CAVLC) scheme. The first VLC, coeff_token, encodes both the total number of nonzero coefficients and the number of trailing ones. There are four choices of look-up table to use for encoding coeff_token for a 4×4 block. In this paper we discuss the results of assigning shorter codes to more probable pairs (Num-coeff, T1s) adaptively and vice versa. There are big gaps between the probability lines of three pairs ( (0,0),(1,1) and (2,2) ), so adaptive probability updating can't give better results. The probability lines of other pairs intersect each other and adaptive probability updating gives better results, but the probability (≈10 %) of these pairs is very small.