Opened 2 years ago

Closed 2 years ago

#175 closed defect (fixed)

Incorrect derivation of CCLM parameter b

Reported by: yyasugi Owned by:
Priority: major Milestone: VVC D4 v2
Component: spec Version: VVC D4 v3
Keywords: CCLM Cc: ksuehring, bbross, XiangLi, fbossen, jvet@…

Description

In 8.3.4.2.8 (Specification of INTRA_LT_CCLM, INTRA_L_CCLM and INTRA_T_CCLM intra prediction mode), the equation 8-219 is incorrect.

b = ( ( 3 + x − y ) < 1 ) ? Sign( a ) * 15 : a (8-219)

It should be a calculation of intercept:

b = ( ( 3 + x − y ) < 1 ) ? minC - ( a * minY ) : minC - ( ( a * minY ) >> k ) (8-219)

Change history (4)

comment:1 Changed 2 years ago by bbross

  • Version changed from VVC D4 v1 to VVC D4 v2

comment:2 Changed 2 years ago by bbross

  • Version changed from VVC D4 v2 to VVC D4 v3

comment:3 Changed 2 years ago by Tomohiro Ikai

The reported fix seems not correct. Could you use the following fix?

b = minC − ( ( a * minY ) >> k ) (8 219)

# This text is the same as proposed in JVET-M0064-v1 and matchs with VTM-4.0 software.
# I talked with the reporter and he confirmed the above fix.

comment:4 Changed 2 years ago by bbross

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

Fixed in v4 of VVC D4

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