JVET-P1026 Non-CE6: Combination of JVET-P0196 and JVET-P0392 on applying LFNST for ISP Blocks and simplifying the transform signalling [S. De-Luxán-Hernández, V. George, G. Venugopal, J. Brandenburg, B. Bross, H. Schwarz, D. Marpe, T. Wiegand (HHI), M. Koo, M. Salehifar, J. Lim, S. Kim (LGE), J. Lainema (Nokia)] [late]
This document combines proposals JVET-P0196 and JVET-P0392. The following results are reported: 0.19% gain, 101% EncT and 100% DecT for AI and 0.18% gain, 101%, 100% DecT in the RA case.
This proposal combines two aspects present in JVET-P0196 and JVET-P0392:
- MTS signalling is moved from the transform unit syntax to after LFNST signalling.
- The restriction that disallows the usage of LFNST if the CU is using ISP is removed.
In the proposed syntax, both LFNST and MTS are signalled in the same place (at the end of the CU) and both are signalled conditionally to the last significant position syntax element. This aspect is compatible with the removal of the ISP-LFNST restriction, so that now the LFNST can be applied to all intra-predicted blocks with the appropriate size.
More details of these aspects can be found in JVET-P0196 and JVET-P0392.
Already in VTM6, the LFNST flag depends on last position. In the proposal, this now also applies to MST flag (same rule is kept as currently for LFNST).
Further, LFNST is also applied to ISP.
Cross check confirms results, text/software is also confirmed
Straightforward change, results show that the gain of the two proposals is additive.
No CE was planned on this.
Decision: Adopt JVET-P1026.