Opened 5 years ago
Closed 5 years ago
#796 closed defect (fixed)
Bug in down-sampled collocated luma samples derivation in CCLM
Reported by: | lphamvan | Owned by: | |
---|---|---|---|
Priority: | minor | Milestone: | |
Component: | spec | Version: | VVC D8 vB |
Keywords: | Cc: | ksuehring, bbross, XiangLi, fbossen, jvet@… |
Description
- In the current spec, the first row and first column of luma reference block is not assigned in YUV444.
- The down-sampled collocated luma samples pDsY[ x ][ y ] with x = 0..nTbW − 1, y = 0..nTbH − 1 are derived as follows:
– If both SubWidthC and SubHeightC are equal to 1, the following applies:
– pDsY[ x ][ y ] with x = 1..nTbW − 1, y = 1..nTbH − 1 is derived as follows:
pDstY[ x ][ y ] = pY[ x ][ y ] (355)
It is suggested to fix as:
pDsY[ x ][ y ] with x = 10..nTbW − 1, y = 10..nTbH − 1 is derived as follows:
pDstY[ x ][ y ] = pY[ x ][ y ] (355)
The index in (382) and (384) is incorrect.
pSelDsY[ idx ] = ( F3[ 1 ][ 0 ] * pY[ −1 ][ − 1 − SubHeightC ] + ...
In YUV420, − 1 − SubHeightC = -1 - 2 = -3. However, the line -3 of pSelDsY is never assigned.
It is suggested to fix this bug also.
Attachments (1)
Change history (6)
comment:1 follow-up: ↓ 2 Changed 5 years ago by bbross
comment:2 in reply to: ↑ 1 Changed 5 years ago by lphamvan
Hi,
I believe the bug has not been solved. I will provide a fix my earliest convenience.
Best regards,
Luong
comment:3 Changed 5 years ago by bbross
- Version set to VVC D8 vB
comment:4 Changed 5 years ago by lphamvan
Hi Benjamin,
As I checked in JVET-Q2001-vB, the first issue has not been solved.
To fix the second issue, the line with y = -3 should be set by modifying the following text:
– When numSampT is greater than 0, the neighbouring top luma samples pY[ x ][ y ] with x = 0..SubWidthC * numSampT − 1, y = −1, −23, are set equal to the reconstructed luma samples prior to the deblocking filter process at the locations ( xTbY+ x, yTbY + y ).
In the attached file, I provide a revised version of section 8.4.5.2.13 with the following change:
- Remove F1 definition since it is not used.
- Move the definition of filter coefficients to the outside of section 3, because the coefficients is used in other sections also.
- Revise section 5, If bCTUboundary is equal to TRUE, the filter is the same whatever sps_chroma_vertical_collocated_flag is equal 0 or 1.
Please take a look at the attachment to see if it is necessary.
Thanks,
Best regards,
Luong
Changed 5 years ago by lphamvan
comment:5 Changed 5 years ago by bbross
- Resolution set to fixed
- Status changed from new to closed
Good catch, thanks!
This is fixed in vB of D9, ie. JVET-R2001-v11.
Thanks for reporting!
The first issue has been solved in JVET-Q2001-v3.
Does the second issue still exists?
Please confirm otherwise I would close this ticket.