JVET-AG0200 Non-EE2: Inter CCP merge mode with zero luma CBF [Z. Deng, K. Zhang, L. Zhang (Bytedance)]
In ECM-11.0, inter CCP merge mode is allowed only if luma CBF is non-zero. In this contribution, it is proposed to allow inter CCP merge mode when the luma CBF is equal to 0. The proposed method is applied on SCC sequences. The impact on coding efficiency and runtimes of the proposed method over ECM-11.0 are reportedly for {Y, U, V, EncT, DecT}:
RA :
class F { 0.02%, -0.28%, -0.49%, 100.9%, 101.1% }
class TGM { -1.26%, -3.61%, -3.61%, 101.1%, 100.7% }
LDB :
class F { -0.17%, -1.43%, -1.69%, 101.5%, 100.8% }
class TGM { -0.90%, -5.74%, -5.84%, 101.2%, 100.9% }
In current ECM, inter CCP merge mode is applied to both natural content and screen content. However, this proposal only applies the proposed change to screen content.
The proposed method requires an additional CU-level flag to be signaled when merge skip mode is applied, and when luma CBF or root CBF is equal to 0, which does not give good performance vs. complexity tradeoff for natural content in preliminary implementation. It was commented that having different signaling conditions for inter CCP merge mode for natural content vs. screen content is not desirable. The proponent is asked to bring results for natural content as well, using the same normative condition for natural and screen content.
It was agreed to investigate this in the EE. Camera-captured content results were requested along with screen content results.