JVET-Q0470 Conditional signalling of SAO [G. Li, X. Li, X. Xu, S. Liu (Tencent)]
In this contribution, it is proposed to conditionally signal SAO in SPS depending on the ALF usage at sequence level. The proposed methods were implemented on top of VTM-7.0, and simulations were conducted with common test conditions. It is reported that compared with VTM-7.0 anchor, the proposed method has overall performance as following.
• ALF on: AI 0.00%, RA 0.08%; LB 0.09%
• ALF off: AI 0.00%, RA 0.00%, LB 0.00%
The proposal would invoke ALF and SAO alternatively.
However, SAO and ALF have different effects, and may also differently be used by other visual-quality optimized encoders than VTM (which is purely targeting PSNR vs. rate optimization).
Complexity-wise, there is no problem, as SAO has rather low complexity compared to ALF. Any encoder can disable SAO, why should that be done normatively?
No action.