JVET-AL0232 Non-EE2: on TALF input extension [C. Ma, X. Xiu, X. Wang (Kwai)]

In ECM16.1, temporal adaptive loop filter (TALF) takes the samples in the reference picture as inputs. This contribution proposes to additionally utilize the reconstructed samples in the current picture right before adaptive loop filter (ALF) as the additional input to the TALF. On top of ECM-16.1, simulation results are reported as below:

RA : {-0.02%, 0.04%, 0.06%, 100.3%, 100.2%},

LDB : {-0.03%, 0.00%, 0.17%, 100.0%, 99.5%};

9 additional luma samples are filtered, which might not explain the increase of encoder and decoder runtime in RA. With the numbers reported here, the tradeoff would not be convincing.

It was commented that the additional usage of samples from the current frame appears not necessary, as TALF is operated in parallel with ALF which does filtering of the same samples anyway. The proponent believes that it might be useful as the optimization of the spatial filtering is considering its combined effect with the temporal filtering, whereas ALF and TALF are currently optimized independently.

Several experts supported to study the proposal in an EE.