Subclause 8.6.1 - IBC SINGLE_TREE case processing chroma in monochrome

[crosewarne]

In subclause '8.6.1 General decoding process for coding units coded in IBC prediction mode':

Steps 1-4 include sub-steps conditioned as 'When treeType is equal to SINGLE_TREE..' followed by chroma-related operations. These are block vector derivation, prediction samples generation, residual samples decoding, and reconstructed samples generation, for steps 1-4, respectively.

These steps seem to be performed regardless that sps_chroma_format_idc could be equal to 0. I think they should be also conditioned on sps_chroma_format_idc is not equal to 0.

This was seen in the 2020/08 release of H.266, and in the version present in the JVET-X1004 errata report.

The above suggestion would align VVC to VTM.

[yk]

Thanks! This will be fixed in the VVC attachment of JVET-Y1004, and the ITU-T VVC v2 text, and the ISO/IEC VVC v2 FDIS text.