JVET-AJ0164 AhG12: On advanced SBT with position and direction inference [G. Laroche, M. Rousselot, P. Onno (Canon)]

This contribution presents an Advanced SBT (ASBT) mode. In this proposed subblock residual coding mode, the position and the direction of the transform subblocks are determined based on the corresponding Inter predictor block. This ASBT mode is signalled at Transform Unit level and it can be applied on SBT transform units and other transform units as well. This ASBT mode is only applied for Inter coding blocks.

Compared to ECM-14.0, the average BDR gains and runtimes reported in this contribution are as follows:

-0.09% -0.05% -0.01% 102.1% 99.7% for the RA configuration,

-0.14% -0.12% -0.39% 103.8% 99.3% for the Low Delay B configuration.

Was initially presented Sunday 1750 in another category

This is an additional (independent) mode, existing SBT not changed, ASBT is operated at CU level. Interesting gain, but encoder runtime is quite large.

It was agreed to investigate this in an EE.

Follow-up discussion:

The following aspects should be investigated for this contribution: granularity of the possible position is set to 4 instead of 1, the new proposed SBT is not allowed after SBT and only the position or the direction is inferred.

It was further suggested to investigate if the same approach could be implemented on top of SBT, rather than being a separate tool.