6.2.2SCE1 related (intra prediction)
JCTVC-M0091 Non SCE1: Low-pass filter for Combined Intra Prediction [A. Alshin, E. Alshina (Samsung)]
This contribution contains description of an Intra prediction scheme that is mixture of inter-layer texture and enhancement layer (EL) intra prediction. A 2D separable symmetrical 5-tap low-pass filter is used for non-trivial combination of two predictions. This allows using low frequencies of inter-layer texture prediction and high frequencies of EL in combination. The scheme reportedly shows an average 0.6% Luma and 1.8% Chroma BD-BR gain (all-intra ×2) and 0.2% Luma and 0.8% Chroma BD-rate gain (all-intra ×1.5).
Immediate adoption was not requested – rather it was suggested to be investigated in a CE.
Some increase in complexity was noted, although it was asserted that this does not increase memory bandwidth as proposed.
A relationship with LP filtering of the base layer was noted. The proponent indicated that such filtering can help in SNR scalability but does not seem to help with spatial scalability, whereas this technique can help with spatial scalability.
The need for multiplications for the filtering was noted, and the proponent asserted that there is a multiplication-free variant.
Another variant (JCTVC-M0195, tested in CE4) was suggested to potentially be lower in complexity and more consistent between spatial and SNR processing cases. CE 4.2.2 would also have some relationship.
The performance-complexity tradeoff needs to be assessed to see whether the asserted gain of about 0.4% is of interest. No action.
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