JVET-W0136 Suggested initial profile text for VVC operation range extension [T. Ikai, T. Chujoh, T. Aono, S. Deshpande (Sharp)] [late]
This was initially presented in a joint meeting on Tuesday 13 July, 0730-0845. See the notes of that discussion in section 7.3.
A new version of this document was presented in session 21, which had been updated with the set of profiles decided in the joint session. It furthermore suggested allocations of profile_idc values and constraint flags, which follow the general principles used traditionally.
Furthermore, a general_lower_bit_rate_constraint_flag was proposed which allows specifying two different ranges of bit rate in the high tier. This can be set to zero or one in still picture and Intra profiles (except Main 12). It is noted that a similar mechanism is used in HEVC intra profiles to accommodate the case that the bit rate in all-intra coding could get significantly higher than when interpicture prediction is available to improve coding efficiency.
It was pointed out by one expert that the document defines activation/deactivation of the palette mode and other tools in the proposed Main 12 profile via GCI flags. This is different from the approach used in V1, where this is typically defined by prescribing the value of the corresponding SPS flag rather than a GCI flag.
Decision: Adopt the profile specification of JVET-W0136v5 (including the modification of the tool enabling/disabling via SPS flags rather than GCI, and align the level definition with that of HEVC).
This was further discussed in the plenary on Friday 16 July at 0510 UTC.
Due to the fact that VVC has a larger number range of profile_idc values, the numbering scheme from HEVC appears not desirable. Furthermore, GCI is optional, therefore it does not fulfil exactly the same purpose as the constraint flags in HEVC.
Also in version 1, individual profile_idc values had been used.
It was left to the discretion of the editors to select appropriate profile_idc values for the new profiles, and also to take care that the nesting relationship is appropriately reflected. The same GCI flag for bit rate constraint will be defined for the different profiles but not required to have particular values associated with profile_idc. It was further agreed that the new flag would not be conditioned on profile_idc.
It was further pointed out that currently no GCI flags have been defined for the other new tools. This is for further study.