Opened 9 years ago

Closed 9 years ago

#648 closed defect (invalid)

Incorrect derivation process of ctxIdxInc for the syntax element significnat_coeff_flag

Reported by: tsukuba Owned by: bbross
Priority: minor Milestone:
Component: Text Version: D8 (J1003) d7
Keywords: Cc: bbross, wjhan, jct-vc@…

Description

In "9.3.3.1.4 Derivation process of ctxIdxInc for the syntax element significant_coeff_flag",

there is a mismatch (bold type) on eq.(9-26) between D8/J1003 d7 and HM7.2-dev(r2666).

According to HM7.2-dev(r2666) or the adopted text of JCTVC-J0256,
the offset value on 8x8TU is dependent on the scanIdx in both luma and chroma as follows;
TComTrQuant.cpp::Int TComTrQuant::getSigCtxInc(...) {
...
Int offset = blockType == 3 ? (scanIdx==SCAN_DIAG ? 9 : 15) : (textureType == TEXT_LUMA ? 21 : 12);
...}

However, in D8/J1003 d7 eq.(9-26) is not matched with the above.

–The variable sigCtx is modified as follows.

–If cIdx is equal to 0, the following applies.

...
–If log2TrafoSize is equal to 3, the following applies.

sigCtx += ( scanIdx = = 0 ) ? 9 : 15 (9-24)

...

–Otherwise (cIdx is greater than 0), the following applies.

–If log2TrafoSize is equal to 3, the following applies.

sigCtx += 9 (9-26)

...

So, eq.(9-26) should be modified as follows;

sigCtx += ( scanIdx = = 0 ) ? 9 : 15

Change History (2)

comment:1 Changed 9 years ago by DefaultCC Plugin

  • Cc bbross wjhan jct-vc@… added

comment:2 Changed 9 years ago by fbossen

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

scanIdx is always equal to SCAN_DIAG for chroma blocks of size 8x8

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  • Benjamin Bross(Owner, Subscriber)
  • Frank Bossen(Participant)
  • jct-vc@…(Subscriber)
  • karl.sharman@…(Always)
  • Karsten Suehring(Always)
  • Takeshi TSUKUBA(Reporter)
  • Woo-Jin Han(Subscriber)