Fast intra mode prediction algorithms for SCBs in VVC SCC

Versatile Video Coding (VVC) now supports Screen Content Coding (SCC) with the introduction of two new coding modes: Intra Block Copy (IBC) and Palette (PLT). However, the numerous modes and the Quad-Tree Plus Multi-Type Tree (QTMT) structure inherent to VVC contribute to a very high coding complexity. To effectively reduce the computational complexity of VVC SCC, we propose a fast Intra mode prediction algorithm for VVC SCC. More specifically, we first use the different minimum Sum of Absolute Transformed Differences (SATD)value of four Directional Modes (DMs)of Intra and the SATD value of the IBC-merge mode to determine whether to early skip Intra. Subsequently, we use a decision tree to determine whether to early terminate block differential pulse coded modulation (BDPCM) checking. Finally, we employ a decision tree to determine whether to early skip multiple transform selection (MTS) and low frequency non-separable transform (LFNST) checking. The results demonstrate that our algorithm achieves an average encoding time reduction of 34.34% with a negligible increase of only 0.46% in BDBR.