Improving Picture Boundary Handling for Video Coding Beyond HEVC
Han Gao, Zhijie Zhao, Eckehard G. Steinbach, Jianle Chen · 2018
Block partitioning is an essential component of today's hybrid video codecs. In order to support video sequences with arbitrary spatial resolution, the HEVC standard and the JEM reference software utilize a forced quadtree (QT) method to process CTUs/CUs located at the picture boundaries. While the forced QT method is simple to implement, it is unsatisfactory from a coding efficiency perspective. To improve the compression performance, novel block partitioning methods are currently being proposed. Our approach for picture boundary handling uses a binary tree (BT) based splitting scheme to deal with the boundary located CTUs/CUs. We present two variants with the first one combining forced BT with forced QT partitioning (forced QTBT) and the second one adaptively choosing between BT and QT (adaptive QTBT). Experimental results obtained with the JEM-6.0 reference software after integrating our approaches demonstrate that our proposed methods provide an average luma BD-rate reduction of 0.85% for the forced QTBT scheme and 0.96% for the adaptive QTBT scheme when using the random access configuration.