JVET-AM0110 AHG12: Weighted averaging for bi-directional samples of TALF [K. Takada, S. Deshpande (Sharp)]

This contribution proposes to derive and signal the weight information for averaging the bi-directional samples of Temporal ALF when the bi-filtering mode is selected on a slice or picture. The weight information is signalled as APS parameters, and it is supported to switch the weights on a CTU basis. The proposal is implemented on the top of ECM-17.0. The BD-rate PSNR of proposed approach compared to ECM-17.0 is as follows:

• RA: {0.00%, -0.01%, 0.06%} for {Y, Cb, Cr} and 100.6%/100.4% for EncT/DecT
• LDB: {-0.04 %, 0.04 %, -0.05 %} for {Y, Cb, Cr} and 100.9%/99.0% for EncT/DecT

Discussion chaired by Y. Ye.

Proposed weights are signalled in the APS, and can be switched at the CTU level.

The proposed method allows the weight values of 0 and 4, which effectively allows the switching between bi and uni TALF at the CTU level.

It was commented that there is no gain in RA, and the LDB gain is mainly coming from class E, which is known to have unstable performance.

Further study was recommended.