JCTVC-M0361 Cross-check of motion field compression in RefIdx mode (JCTVC-M0135) [P. Onno (Canon)] [late]
JCTVC-M0192 Improved temporal motion vector prediction for reference index based SHVC [X. Xiu, Y. Ye, Y. He, Y. He (InterDigital)]
In this contribution, the temporal motion vector prediction (TMVP) process in the reference index based solution of SHVC Test Model (SHM1.0) is modified to reportedly improve the enhancement layer (EL) coding efficiency. First, it is proposed to modify the derivation processes of the selected reference list of the co-located PU and the target reference index of the current PU when generating the TMVP candidate of EL merge mode, such that the motion vector (MV) scaling operation could be skipped when possible. Second, it is proposed to place the TMVP candidate before the spatial candidates in the advanced motion vector prediction (AMVP) candidate list. In addition, the pruning is performed between the TMVP candidate and each spatial candidate to remove MV redundancy. Finally, given the constant zero MVs used for the inter-layer prediction (ILP) in reference index based SHVC, it is proposed to skip signaling MVs when the ILP picture is used. Experimental results show that the proposed tools reportedly achieve 0.1%, 0.8%, 0.6% and 0.6% BD-rate savings on average for AI, RA, LD-P and LD-B, respectively, compared to the anchors of the reference index based SHM1.0.
The proposal would introduce block-level changes to the decoding process of the refidx framework. It shows benefit in compression by doing this.
As a general remark, JCT-VC plenary should further discuss what the concept of “HL syntax only” vs. “block level changes” means.
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