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

5.13Quantization

5.13.1QP prediction / delta QP coding

5.13.2General

Action on the proposals for modification of delta QP coding:

• 
  It is generally desirable to decrease the possible maximum throughput at minimum loss in compression performance (J0089 and J0298 would give that)
  
• 
  Structure of binarization should be consistent with schemes used for other syntax elements, e.g. MV differences
  

Decision: Adopt J0089 (Cmax = 5), as it better fits the second criterion, and was already (similarly) proposed in the last meeting.

5.13.3Contributions

JCTVC-J0060 AHG5: Simplified cu_qp_delta coding [K. Chono (NEC)]

This contribution presents a simplified cu_qp_delta coding based on EG0 binarization. The simplified scheme maps a given cu_qp_delta into the unsigned value and represents it with the EG0 binary string. Only the first bin of the EG0 binary sequence is context-coded; the rest are bypass-coded. Thus it reduces the number of context-coded bins of cu_qp_delta in worst-case scenario from 11% to 2%. It is reportedly shown that the simplified scheme changes BD-rate results by 0.20% on average in AHG5 common test conditions.

The relatively large loss (compared to other proposals) is asserted to be due to change in mode decision.