Opened 2 years ago
Closed 2 years ago
#1488 closed defect (fixed)
Incorrect equation in D.7.2 Subpicture level information SEI message semantics
Reported by: | adybrowne | Owned by: | |
---|---|---|---|
Priority: | minor | Milestone: | |
Component: | spec | Version: | VVC D10 vH |
Keywords: | Cc: | ksuehring, bbross, XiangLi, fbossen, jvet@… |
Description
Currently the MinCR constraint for subpictures for AU 0 is defined as:
– The sum of the NumBytesInNalUnit variables for AU 0 corresponding to the j-th subpicture sequence shall be less than or equal to
FormatCapabilityFactor * ( Max( AuSizeMaxInSamplesY[ 0 ] * OlsRefLevelFraction[ i ][ j ][ k ] ÷ 256, FrVal * MaxLumaSr * OlsRefLevelFraction[ i ][ j ] ÷ 256 ) + MaxLumaSr * ( AuCpbRemovalTime[ 0 ] − AuNominalRemovalTime[ 0 ] ) * OlsRefLevelFraction[ i ][ j ][ k ] ) ÷ ( 256 * MinCr ),
where MaxLumaSr and FormatCapabilityFactor are the values specified in Table 136 and Table 137, respectively, that apply to AU 0, at level sli_ref_level_idc[ i ][ k ], and MinCr, AuSizeMaxInSamplesY[ 0 ] and FrVal are derived as specified in A.4.2.
Two issues exist.
Firstly, there is a missing index [k] for OlsRefLevelFraction in the second part of the Max evaluation.
Secondly, both parts of the Max evaluation have a division by 256. This division is already covered by the division (256 * MinCr) at the end of the calculation.
Hence the corrected text for the calculation could be:
FormatCapabilityFactor * ( Max( AuSizeMaxInSamplesY[ 0 ] * OlsRefLevelFraction[ i ][ j ][ k ], FrVal * MaxLumaSr * OlsRefLevelFraction[ i ][ j ][ k ] ) + MaxLumaSr * ( AuCpbRemovalTime[ 0 ] − AuNominalRemovalTime[ 0 ] ) * OlsRefLevelFraction[ i ][ j ][ k ] ) ÷ ( 256 * MinCr )
Alternatively, the division by 256 could be moved from the last part of the calculation to the third use of OlsRefLevelFraction:
FormatCapabilityFactor * ( Max( AuSizeMaxInSamplesY[ 0 ] * OlsRefLevelFraction[ i ][ j ][ k ] ÷ 256, FrVal * MaxLumaSr * OlsRefLevelFraction[ i ][ j ][ k ] ÷ 256 ) + MaxLumaSr * ( AuCpbRemovalTime[ 0 ] − AuNominalRemovalTime[ 0 ] ) * OlsRefLevelFraction[ i ][ j ][ k ] ÷ 256 ) ÷ MinCr
A third alternative would be to extract the OlsRefLevelFraction[i][j][k] as a common factor as follows:
FormatCapabilityFactor * ( Max( AuSizeMaxInSamplesY[ 0 ], FrVal * MaxLumaSr ) + MaxLumaSr * ( AuCpbRemovalTime[ 0 ] − AuNominalRemovalTime[ 0 ] ) ) * OlsRefLevelFraction[ i ][ j ][ k ] ÷ (256 * MinCr)
Change history (2)
comment:1 Changed 2 years ago by skupin
comment:2 Changed 2 years ago by yk
- Resolution set to fixed
- Status changed from new to closed
Good catch! Thanks Adrian for the fix and Robert for confirming! Will be fixed in the VVC attachment of JVET-W1004-v1 (taking the third alternative fix).
Thanks Adrian, I can confirm the two issues and have a preference for your third proposed alternative fix.