Opened 6 years ago
Closed 6 years ago
#135 closed defect (invalid)
DCT2 transform matrix down-sampling might be wrong in the spec
| Reported by: | zhou | Owned by: | |
|---|---|---|---|
| Priority: | minor | Milestone: | |
| Component: | spec | Version: | VVC D3 v8 |
| Keywords: | Cc: | ksuehring, bbross, XiangLi, fbossen, jvet@… |
Description
The matrix down-sampling is only done for columns, it should be done for rows too.
Replace
If trType is equal to 0, the following transform matrix multiplication applies:
y[i]= ∑_("j" =0)("nonZeroS" -1)▒〖transMatrix[i][j*2(6-Log2(nTbS)) ]*x[j]〗 with i = 0..nTbS − 1 (8 567)
with
If trType is equal to 0, the following transform matrix multiplication applies:
y[i]= ∑_("j" =0)("nonZeroS" -1)▒〖transMatrix[i(6-Log2(nTbS))][j*2(6-Log2(nTbS)) ]*x[j]〗 with i = 0..nTbS − 1 (8 567)
Change history (6)
comment:1 Changed 6 years ago by zhou
- Summary changed from DCT2 transform matrix down-sampling might is wrong in the spec to DCT2 transform matrix down-sampling might be wrong in the spec
comment:2 Changed 6 years ago by bbross
- Version set to VVC D3 v6
comment:3 Changed 6 years ago by bbross
- Version changed from VVC D3 v6 to VVC D3 v7
comment:4 Changed 6 years ago by bbross
comment:5 Changed 6 years ago by bbross
- Version changed from VVC D3 v7 to VVC D3 v8
comment:6 Changed 6 years ago by bbross
- Resolution set to invalid
- Status changed from new to closed
As already mentioned it is the same as in HEVC where the first nTbS basis functions are selected from the Matrix (no subsampling!) and then subsampled (this is the column subsampling).
See also Fig. 6.2 in the HEVC book.
So no issue here.
The downsampling is done the same way as it is done for HEVC, so is there a bug in HEVC as well?
(see equation (8-319) of HEVC v5)