Opened 12 years ago

Closed 11 years ago

#500 closed defect (fixed)

Redundant cbf_cb and cbf_cr flags when log2MaxTrafoSize is set to two

Reported by: zhyang123 Owned by: bbross
Priority: minor Milestone:
Component: Text Version: D6 (H1003) dI/dJ/dK
Keywords: Cc: bbross, wjhan, jct-vc@…


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 )

Change History (2)

comment:1 Changed 12 years ago by DefaultCC Plugin

  • Cc bbross wjhan jct-vc@… added

comment:2 Changed 11 years ago by bbross

  • Resolution set to fixed
  • Status changed from new to closed

firstChromaCbf does not exist in D7 anymore

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  • Benjamin Bross(Owner, Subscriber, Participant)
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  • Karsten Suehring(Always)
  • Woo-Jin Han(Subscriber)
  • Zhijie Yang(Reporter)