Extended Quad-tree Partitioning for Future Video Coding

The quad-tree plus binary-tree (QTBT) coding unit (CU) partitioning structure, which has been adopted to the next generation video coding standard, shows promising coding performance when compared with the conventional quad-tree structure in HEVC. In this paper, we propose the Extended Quad-tree (EQT) partitioning, which further extends the QTBT scheme and increases the partitioning flexibility. More specifically, EQT splits a parent CU into four sub-CUs of different sizes, which can adequately model the local image content that cannot be elaborately characterized with QTBT. Meanwhile, EQT partitioning allows the interleaving with BT partitioning for enhanced adaptability. Experimental results on the JEM7-QTBT-Only platform show that EQT brings better coding performance with 3.17%, 3.20% and 3.06% BD-Rate gains under random access, low-delay P and low-delay B configurations, respectively.