JVET-R0216 AHG9: Signalling the parallel merge level relative to the minimum coding block size [R. Yu, M. Pettersson, R. Sjöberg, M. Damghanian, Z. Zhang, J. Enhorn, J. Ström (Ericsson)]

In the current VVC draft specification, the minimum luma coding block size is specified in the SPS. The allowed range for the minimum luma coding block size is from 4 to Min( 64, CTU size ). In the Brussels JVET meeting, a parallel merge mechanism was adopted in VVC. The mechanism allows parallel derivation of merge candidate lists for blocks within a certain size of a region, which is also referred to as the parallel merge level. The parallel merge level is signalled in the SPS and it indicates the size of the region wherein parallel merge is possible. The allowed range for the parallel merge level is from 4 to the CTU size.

It is reported in this contribution that the current specification allows signalling of the parallel merge level to be smaller than the minimum coding block size, which is asserted to be confusing and unnecessary. It is therefore proposed to signal the parallel merge level relative to the minimum coding block size. It is claimed that the proposed signalling cleans up the signalling of the parallel merge level and brings some minor bit-savings.

JVET-R0237 is related. See further notes there.

No action was taken on this.