Similar to the previous HM ticket #312, the working draft also has the issue that when log2MaxTrafoSize is two, there are three redundant cbf_cb and cbf_cr flags for each 4x4 chroma TU.

In section 7.3.8 transform tree syntax, firstChromaCbf is derived as follows:

firstChromaCbf = ( log2TrafoSize = = Log2MaxTrafoSize | | trafoDepth = = 0 ) ? 1 : 0

The above formula does not consider the case when log2MaxTrafoSize is two. In that case, bFirstCbfOfCU is always true for each 4x4 luma TU, which in turn causes a set of cbf_cb and cbf_cr flags to be coded. Although only the 4th luma TU is associated with a chroma TU and should contain a set of coded cbf_cb and cbf_cr flags.

A possible fix may be to replace the above formula by the following one

firstChromaCbf = ((log2TrafoSize == log2MaxTrafoSize && (log2TrafoSize > 2 || blkIdx == 3)) || trafoDepth == 0 )