Opened 12 years ago

Closed 12 years ago

#313 closed defect (fixed)

Missing QpBdOffsetC in equations for deriving chroma QPs

Reported by: hao Owned by: bbross
Priority: minor Milestone:
Component: Text Version: WD5 (G1103) d9
Keywords: Cc: bbross, wjhan, jct-vc@…


The derivation of chroma QPs (p.83) is described as follows.

The values of QP'Cb and QP'Cr are derived as
QP'Cb = Clip3(0, 51, QP'Y + chroma_cb_qp_offset) (7-22)
QP'Cr = Clip3(0, 51, QP'Y + chroma_cr_qp_offset) (7-22)

QpBdOffsetC should be employed here, for example as follows.

QP'Cb = Clip3(0, 51+QpBdOffsetC, QP'Y + chroma_cb_qp_offset) (7-23)
QP'Cr = Clip3(0, 51+QpBdOffsetC, QP'Y + chroma_cr_qp_offset) (7-24)

Change History (3)

comment:1 Changed 12 years ago by DefaultCC Plugin

  • Cc bbross wjhan jct-vc@… added

comment:2 in reply to: ↑ description Changed 12 years ago by hao

Sorry, my example description is not correct.

They should be:

QPCb = Clip3(-QpBdOffsetC, 51, QPY + chroma_cb_qp_offset) (7-23)
QPCr = Clip3(-QpBdOffsetC, 51, QPY + chroma_cr_qp_offset) (7-24)

QP'Cb = QPCb + QpBdOffsetC (7-25)
QP'Cr = QPCr + QpBdOffsetC (7-26)

comment:3 Changed 12 years ago by wjhan

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

Software seems to use clipping range from 0 to 51, thus I fixed WD as follows as a initial step for other QP-related changes:

QP'Cb = Clip3(0,51,QPY+chroma_cb_qp_offset)+QpBdOffsetC
QP'Cr = Clip3(0,51,QPY+chroma_cr_qp_offset)+QpBdOffsetC

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  • Benjamin Bross(Owner, Subscriber)
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