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Non-CE5: Fixes of ALF sample padding
Abstract
In the current VVC design, when performing ALF, four boundaries of a CTU are checked to determine the invoking of sample padding. If a boundary is a slice/brick/sub-picture/360 virtual boundary and filtering across such boundary is disallowed, sample padding is applied. However, just checking the four boundaries of a CTU couldn’t cover all possible cases that padding should be applied. For example, in the case that the above-left, above-right, below-left or below-right neighboring samples of the CTU are in a different slice/brick/sub-picture from the CTU and filtering across the slice/brick/sub-picture boundary is disallowed, sample padding may also be required. This contribution proposes to fix these issues by checking more boundaries of the CTU. It is asserted that proposed method has not impact on the coding performance in CTC.
JVET-P0492 Non-CE5: Fixes of ALF sample padding [H. Liu, L. Zhang, K. Zhang, Y. Wang, J. Xu, Y. Wang (Bytedance)]
Contributions JVET-P0121, JVET-P0156, JVET-P0492, JVET-P0552 are related.
It is proposed to use the top left sample of the current slice to pad the unavailable samples (for the top left case). The check is done similar to JVET-P0552. The proposals checks all four corners (similar to JVET-P0492) although it was mentioned that only top left and bottom right are needed.
References:
Cited:
PATENTS:
US20240129462A1
1.00
2024-04-18
US11683488B2
0.34
2023-06-20
US20230156189A1
0.32
2023-05-18
US12003712B2
0.30
2024-06-04
US11553179B2
0.28
2023-01-10
US12069262B2
0.24
2024-08-20
WO2020094010A1
0.22
2020-05-14
US12262006B2
0.20
2025-03-25
Decisions
It is proposed to use the top left sample of the current slice to pad the unavailable samples (for the top left case). The check is done similar to JVET-P0552. The proposals checks all four corners (similar to JVET-P0492) although it was mentioned that only top left and bottom right are needed.
Citation