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-J0205 Cross-check report on removal of zigzag scan from scaling list coding (JCTVC-J0150) [S.-C. Lim, H. Y. Kim, J. Lee (ETRI)]
JCTVC-J0256 Removal of the 8x2/2x8 coefficient groups [J. Sole, R. Joshi, M. Karczewicz (Qualcomm)]

Coefficient coding in HEVC is processed in 4×4 sub-blocks (coefficient groups). The exceptions are the 8×2 and 2×8 sub-blocks for the 8×8 TU when horizontal and vertical scans are used. It is proposed to remove these non-square coefficient groups by using 4×4 based horizontal and vertical scans. The significance map coding is unified for all the scans and for TU sizes larger than 4×4. The performance of the method is 0.06% / −0.03% / −0.02% for AI / RA / LD Main, and 0.09% / 0.00% / 0.02% for AI / RA / LD HE. For the RDOQ off case, results are 0.00% / −0.07% / 0.00% for AI / RA / LD Main and 0.01% / −0.05% / 0.06% for AI / RA / LD HE. The method is combined with the significance map patterns in JCTVC-J0354 giving a performance of 0.02% / −0.06% / −0.02% for AI / RA / LD Main, and 0.06% / −0.04% / 0.07% for AI / RA / LD HE.

Several experts express opinion that this is a desirable unification (using at least same 4x4 sub-block structure) as for other cases

Would also resolve a current bug in the spec for 2x8/8x2

Still uses different sequence of sub-blocks for horizontal and vertical (latter identical to current diagonal) – Q: would it cause a loss when same sequence is used everywhere?

Decision: Adopt J0256 method 1