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CE4-related: Motion vector rounding in enabled hpelIfIdx
Abstract
This contribution proposes 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 round the motion vector reference position to hal-fpel position when hpelfIdx is valid. Simulation results show a overall luma BD-rate 0.01%/0.01% for RA/LDB and no increase in running time comparing VTM-6.0.
JVET-P0533 CE4-related: Motion vector rounding in enabled hpelIfIdx [Y. Kidani, K. Kawamura, K. Unno, S. Naito (KDDI)]
References:
Cited:
PATENTS:
20220217382
0.73
WO/2021/052505
0.73
WO/2021/052504
0.73
WO/2021/052506
0.73
WO/2021/043166
0.34
WO/2025/190402
0.32
WO/2021/036976
0.30
WO/2021/052507
0.26
Decisions
JVET-P0533 CE4-related: Motion vector rounding in enabled hpelIfIdx [Y. Kidani, K. Kawamura, K. Unno, S. Naito (KDDI)]
Citation