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CE4-related: Modified hpelIfIdx derivation for half-pel interpolation filter
Abstract
This contribution proposes an applicable condition of alternative interpolation filter for half-pel position. In the current design, the alternative interpolation filter is determined by the specific index (hpelIfIdx) and motion vector reference position. In merge mode, hpelIfIx of a current block is inherited from existing-coded blocks along with motion vector while the motion-vector reference position locates at half-pel accuracy position if hpelIfIdx is valid. The motion vector reference position, however, may shift from half-pel accuracy position if pairwise average merge mode, MMVD, or DMVR are used. This mismatch causes three problems as follows: 1) The filter applied to the current blocks will become different from that of the inherited block. 2) The mismatch of accuracy will drift to following coded blocks which inherit the hpelIfIdx and motion vector from that of the current block. 3) A bi-predicted inter block consist of blocks filtered by different characteristic’s interpolation. In this contribution, it is proposed to modify the value of hpelIfIdx if motion vector reference position is deviated from hpel position by pair-wise average merge, MMVD or DMVR. Simulation results show a overall luma BD-rate 0.02%/-0.01% for RA/LDB and no increase in running time comparing VTM-6.0.
JVET-P0532 CE4-related: Modified hpelIfIdx derivation for half-pel interpolation filter [Y. Kidani, K. Kawamura, K. Unno, S. Naito (KDDI)]
References:
Cited:
PATENTS:
20210243470
0.70
20240040146
0.70
WO/2020/211870
0.34
20240244181
0.33
3954122
0.32
20230059366
0.31
2020405366
0.30
20250260811
0.28
Decisions
JVET-P0532 CE4-related: Modified hpelIfIdx derivation for half-pel interpolation filter [Y. Kidani, K. Kawamura, K. Unno, S. Naito (KDDI)]
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