JCTVC-G608 Unified Deblocking and SAO [A. Segall, J. Zhao (Sharp)]
In current HEVC test model HM4.0, there are three in-loop filtering processes ― deblocking filter, Sample Adaptive Offset (SAO) and Adaptive Loop filter (ALF). They are processed sequentially. SAO is applied to the debocked pictures. Due to dependency on future deblocked pixels, SAO can not be done immediately after a pixel is fully deblocked. This makes it hard to integrate SAO into parallel deblocking process.
This contribution proposes a simple modification to SAO classification process ― use horizontal deblocked pixels instead of fully deblocked pixels for EO type SAO classification. This eliminates the dependency of SAO of a pixel on future deblocked pixels, and makes it possible to integrate SAO into parallel deblocking process. On average, there is only about 0.1% rate increase on coding performance.
If an SAO offset is known, SAO process is simply an add operation, it would be desirable to be added to a pixel while the pixel is deblocked.
Use horizontal deblocked pixels instead of fully deblocked pixels for EO type SAO classification. For the offset adding step, the offset is still added to the fully deblocked pixels. For BO type, no modification needed.
Bitrates (losses) HE: -0.1/-0.1/0.0/xx LC: -0.1/-0.1/-0.1/xx
Runtime Enc HE: 99/99/100/xx LC: 100/100/99/xx Dec HE: 100/102/104/xx LC: 101/101/102/xx Can this be implemented as one pass also at the encoder? Must be studied.
Some concern that this may complicate the encoder, whereas the benefit seems to be unclear. No action.
JCTVC-G1011 Cross-check results of the Unified Deblocking and SAO of Sharp (JCTVC-G608) [M. Narroschke, S. Esenlik (Panasonic)] [late]
JCTVC-G684 Subjective Tests on ALF and SAO Using HM-4.0 [W.-S. Kim, O. G. Sezer, M. Budagavi (TI)]
This contribution presents results of informal subjective tests conducted on two loop filtering operations in HM-4.0: SAO and ALF. Test videos were presented at their actual frame rates to the viewers. Three configurations were tested using low delay B high efficiency (LB-HE) condition: HM-4.0 Anchor vs.
SAO-off+ALF-off, HM-4.0 Anchor vs. SAO-off+ALF-on, and HM-4.0 Anchor vs. SAO-on+ALF-off. In HM-4.0 Anchor, both SAO and ALF are activated (SAO-on+ALF-on). Among these three configurations, SAO-on+ALF-off gives subjective quality results better than or comparable to the HM-4.0 Anchor. This contribution requests that JCT-VC conducts subjective quality test of SAO and ALF in a core experiment setting to evaluate the subjective quality gains provided by the aforementioned tools, and decide on the
minimal set of configurations that provide the best subjective quality improvements, so that the optimal performance can be achieved in the final standard in terms of implementation cost and visual quality.
Request subjective viewing on SAO and/or ALF Was reported also in previous meeting.
Consider the possibility to conduct some formal subjective viewing in CE8 prior to the next meeting (Minhua takes lead). It is reported that at least 5 companies in the San Jose area would be able to offer viewing facilities for that. Vittorio should get involved in the preparation of such a viewing. To be tested:
ALF on/off with SAO on, possibly also both SAO/ALF on. Should be done with reasonable number of viewers and test cases (i.e. sequences, bit rates).
5.6 Block structures and partitioning 5.6.1 NSQT (ref CE2)
JCTVC-G519 Non-CE2: Harmonization of implicit TU, AMP and NSQT [X. Zheng (HiSilicon), Y. Yuan, Y. He (Tsinghua)]
This contribution provides a harmonization solution of implicit TU, AMP and NSQT. Experimental results show that the proposed solution contributes average coding gain of 0.1% for RA, 0.1% for RA_LC, 0.2% for LD_B, 0.1% for LD_B_LC, 0.1% for LD_P and 0.1% for LD_P_LC. Both encoder and decoder complexity are same as HM4.0.
Decision: It is agreed that this harmonization is desirable. WD and software should be checked by WD editor and Motorola (K. Panusupone). (confirm)
JCTVC-G852 Cross-check report on Harmonization of implicit TU, AMP and NSQT (JCTVC-G519) [I.-K. Kim (Samsung)] [late]
Did not perform concise checking whether software and text match, but the code change is confirmed to be minimum.
JCTVC-G521 Non-CE2: Non-square Hadamard transform for motion estimation and merge estimation [X. Zheng, L. Liu (HiSilicon), Y. Yuan, Y. He (Tsinghua)]
This contribution provides a non-square hadamard transform solution which is used at motion estimation and merge estimation process. Different configurations of non-square hadamard transform are also discussed at the contribution. Experimental results show that non-square hadamard can achieve the average gain of 0.2% for RA, 0.2% for RA_LC, 0.2% for LD_B, 0.3% for LD_B_LC, 0.2% for LD_P and 0.3% for LD_P_LC when inter 2x8 and 8x2 transform is used at residual coding.
Presentation not uploaded.
Decision (SW): Adopt non-normative tools (but not the inclusion of 2x8/8x2 as also suggested in the docnot 2x8/8x2)
JCTVC-G599 Non-CE2: Cross-Check of Non-square Hadamard transform for motion
estimation and merge estimation [S. Oudin, B. Bross(Fraunhofer HHI)] [late]
5.6.2 Partition mode/size coding
JCTVC-G151 Prediction and partition mode binarization for Low Delay P [X. Zhang, S.
Liu, S. Lei (MediaTek)]
This contribution reports a bug fix and a method for binarizing prediction and partition modes for Low Delay P configuration. Firstly, a mismatch was found between WD and HM with regard to the prediction and partition mode binarization for Low Delay P. With the bug fix in HM software, negligible (0.0%) impact is reported on both BD-rate and encoding and decoding runtime. Secondly, it is proposed to unify the prediction and partition mode binarization for Low Delay P and B, which simplifies both WD and HM. Again, experimental results report negligible (0.0%) impact on both BD-rate and encoding and decoding runtime.
Partially already discussed - see under G785.
Deviation between WD and software in binarization for P
JCTVC-G655 Cross-check of JCTVC-G151 on prediction and partition mode binarization for Low Delay P [P. Lai, F. C. A. Fernandes (Samsung)]
JCTVC-G283 Residue Quad Tree Depth for Chroma in Intra Coding [X. Zhao, X. Guo, X.
Li, S. Lei (MediaTek), S. Ma, W. Gao (PKU)]
In HM4.0, luma and chroma components share the same maximum Residue Quad Tree (RQT) depth.
This contribution proposes to use separate maximum RQT depth for luma and chroma components in intra coding. In specific, a user-defined parameter is added in the sequence parameter set (SPS) to allow independent RQT depth setting for chroma. It is reported that with setting the parameter as 0, average BD-Rate reductions of 0.04%, 1.67% and 1.70% are achieved for Y, U and V in AI-HE, respectively, and 0.20%, 2.43% and 2.53% are achieved for Y, U and V in AI-LC, respectively. It is also reported that the decoding time is slightly decreased.
Question: Is there an implicit mode for chroma? Currently not.
JCTVC-G798 Cross verification of MediaTek’s proposed residue quad-tree depth for intra chroma coding (JCTVC-G283) [Y. Chiu, L. Xu (Intel)] [late]
JCTVC-G442 Improvement to chroma TU specification [A. Minezawa, K. Sugimoto, S.
Sekiguchi (Mitsubishi), A. Ichigaya, S. Sakaida (NHK)]
This contribution proposes an improvement to chroma TU structure of the current HM. The proposed method introduces up to 32x32 TU size for chroma when LCU size is 64x64. In addition, it is proposed to apply fixed depth for chroma TU instead of using the same TU depth with luma component. The
proposed method applies TU depth=0 for CU with 2Nx2N PU, and applies TU depth=1 for CU with rectangular PU and NxN PU while TU split for Luma is unchanged from HM-4. The proposed method achieves 2.0%, 2.1% and 1.0% chroma BD-rate gain for AI-HE, RA-HE and LD-HE, and 2.9%, 2.0% and 0.9% chroma BD-rate gain for AI-LC, RA-LC and LD-LC settings with 2-3% encoding time reduction.
Luma BD-rate gain is on average 0.1% and 0.2% for HE and LC settings.
Difference compared to G283: Fixed RQT depth vs. variable RQT depth.