Of itu-t sg16 wp3 and iso/iec jtc1/SC29/WG11

JCTVC-M0371 Non-SCE4: Crosscheck for Fixed Inter-layer Filter for SNR Scalability with Only One Non-unity Coefficient (JCTVC-M0223) [W. Zhang, Y. Chiu (Intel)] [late]
JCTVC-M0224 Non-SCE4.2: Inter-layer Fixed Directional Filtering [P. Lai, S. Liu, S. Lei (MediaTek)]

This contribution proposes an inter-layer filtering method using switched (fixed-value) directional filters. The fixed directional filters use 5 samples within a 3×3 neighborhood of the to-be-filtered sample. To determine which fixed directional filter is to be applied to a given sample, the local edge orientation is identified by computing and comparing local gradients. In the SHM 1.0 IntraBL framework, the filtering process is turned on/off on a CU-by-CU basis using CU-level filter control flag. The test results were reported as follows:

EL+BL luma BD-rates for 2X, AI / RA / LDP / LDB: −0.5% / −0.5% / −0.7% / −0.5%.

EL+BL luma BD-rates for 1.5X, AI / RA / LDP / LDB: −0.1% / 0.0% / −0.4% / −0.1%.

EL+BL luma BD-rates for SNR scalability, RA / LDP / LDB: −0.8% / −1.9% / −0.9%.

The average encoding and decoding runtime are 104% and 106%. The proposed method reportedly has no impact on the worst-case complexity. Per-sample complexity for the filtering process is analysis in this document,

The proponent emphasized that the proposal has low latency, as it does not require the encoder to analyze statistics in order to decide what to signal to control the decoder.

It was remarked that comparators are relatively "expensive" for implementation.

SCE 4.1.1 (M0087) was mentioned as beneficial for the SNR scalability case (although the importance of the SNR scalability case may not be so high).

For further study in CE.