JVET-V0153 AHG12: Cross-component Sample Adaptive Offset [C.-W. Kuo, X. Xiu, Y.-W. Chen, H.-J. Jhu, W. Chen, X. Wang (Kwai)] [late]
In this contribution, one coding tool named Cross-component Sample Adaptive Offset (CCSAO) is proposed for compression efficiency improvement beyond VVC. CCSAO operates as part of SAO process and utilizes the correlation between three components as guidance to further enhance the reconstructive quality of the current sample. Compared to VTM-12.0 anchors with the encoder fix in JVET-V0095, the BD-rate impact of the proposed method is summarized as below.
All Intra | Random Access | Low Delay B | |||||||
Y | U | V | Y | U | V | Y | U | V | |
CCSAO | 0.13% | -2.43% | -2.39% | 0.04% | -3.62% | -3.61% | -0.15% | -8.45% | -8.64% |
The lower gain for intra is asserted to be due to the higher number of parameters that are sent. In RA, it was hardly used for higher temporal IDs.
Gains for RA and LB look interesting.
Question: Could it have impact on visual quality of chroma? Not known, should be investigated.
It was agreed to study this in an EE. It was suggested to also perform a visual investigation with ALF off.
High-level syntax (HLS) proposals (13)
AHG9: SEI message studies and proposals (10)
See also the notes for JVET-V0072 (on RPL constraints) and JVET-V0111 (on decoding unit information), reported as issues for VVC v1.
See also the notes for JVET-V0093 with software for encoder and decoder functionality in section 4.11, which also suggest potential standardization action. JVET-V0093 was initially discussed as an SEI message contribution and the notes were then moved to reflect its potential as an encoder and decoder software functionality enhancement.
Contributions in this area were initially discussed in session 9 at 1300–1500 UTC and session 10 at 1520–1720 UTC on Thursday 22 April 2021 (chaired by GJS and Y.-K. Wang as noted). Further discussion was held in sesssion 15b at 2100-2300 and 2330 on Friday 23 April 2021 – 0020 on Saturday 24 April 2021 (chaired by GJS) and in sesssion 18b at 1650 on Monday 26 April 2021 (chaired by GJS).