JVET-AM0167 Non-EE2: On long-tap interpolation filtering for angular modes [T. Dong, V. Rufitskiy, A. Filippov (TCL)]

This contribution is a combination of aspects proposed in JVET-AM0140 “Non-EE2: Modifications of the unwrapping and interpolation filtering processes for angular modes” and JVET-AM0149 “Non-EE2: On filtering for angular modes”. Besides, a longer-tap interpolation filters are used in intra prediction for DIMD fusion components.

It was commented that some gain may be lost after adoptions (1.7a, 1.12).

It is reported that on top of ECM-17.0, the overall coding performance for {Y, U, V, EncT, DecT} is: {-0.06%, -0.04%, -0.04%, 99.6%, 100.2%} for AI configuration.

It is noted that the switch between 6/8 tap was removed for prediction in EE2-1.7a, whereas the TM currently does not use switching. EE1.7b had proposed to replace the 4tap filter in TM 6tap, but it was not adopted due to complexity vs. insufficient benefit in compression. It appears inconsistent to add even more complexity, and according to proponents it only provides 0.01%.

It was agreed to investigate this in an EE: Aspects 1 and 2 from JVET-AM0140 and aspect 1 from JVET-AM0149 in EE from list above, and the longer-tap filter selection from JVET-AM0167. (separate and in combination). 8-tap filter for TM (without switching) may also be tested. For adoption, also complexity in terms of increased number of operations shall be considered, not only runtime.