The Joint Collaborative Team on Video Coding (jct-vc) of itu-t wp3/16 and iso/iec jtc 1/ sc 29/ wg 11 held its tenth meeting during 11-20 July 2012 at the City Conference Centre (ccc), a k. a

JCTVC-J0373 Cross-check of JCTVC-J0342 on chroma QP range extension [J. Xu, A. Tabatabai (Sony)] [late]

The proposal was supported by the cross-checkers.

5.14Entropy coding

JCTVC-J0194 AHG5: Max exponential golomb code for reducing number of bins [K. Sugimoto, S. Sekiguchi, T. Murakami (Mitsubishi)]

This contribution proposes modifications to the CABAC binarization for ref_idx, cu_qp_delta and sao_offset. In HM-7.0, truncated unary binarization is used for these syntax, which introduces 15, 32 and 32 context coded bins in the worst case. To reduce the throughput of the CABAC, this contribution proposes using kth order Max Exp-Golomb coding. Max Exp-Golomb coding is similar to Exp-Golomb coding, but the longest code is one bit shorter than Exp-Golomb code by truncating the code using the maximum possible index.

The proposed method was implemented in HM-7.0, and it is reported that there is negligible coding efficiency impact with reducing the number of context coded bins per syntax element in the worst case down to 4, 5 and 5.

It is reported that bit rate increase in terms of BD-rate is 0.0% for ref_idx and 0.0–0.1% for sao_offset in CTC. The reported bit rate increase for cu_qp_delta is 0.2% in AHG5 test condition.

It is also proposed to apply 1st order Max Exp-Golomb code for mvd binarization. By signaling motion search range, maximum bins for mvd is also reduced.
Adopting this would mean that another binarization scheme would need to be defined, as EG0 cannot be replaced (is also used for transform coefficients)

Unlike EG0, this method might not have an implicit prefix/suffix error detection capability.

No action.