Algorithm of incorporating error detection into H.264 CABAC

摘要

CABAC is one of the main entropy coding methods in the H.264 video compression standard. As a binary arithmetic coding, CABAC can achieve extremely high compression efficiency, but it is sensitive to channel errors. After analyzing H.264 CABAC framework, an algorithm is proposed to integrate error detection into CABAC. A forbidden symbol is introduced into the coding alphabet and is allocated a small probability. Whenever this redundant interval is observed in the decoder output, an error is detected. Mathematical analysis shows that the distribution of error detection rate approximates geometric probability with the redundancy as its parameter. A small amount of extra redundancy can be very effective in detecting errors very quickly, and the compression efficiency of CABAC will not be noticeably undermined. The value of redundancy can easily be adjusted through a single parameter to suit the error characteristics of the channels in real implementations. Some useful information about the position of the error is also obtained through this error detection scheme, which can substantially improve the efficiency of succeeding error resilience processing. Experimental results confirm these conclusions.