Fast encoding algorithms for geometry-adaptive block partitioning

Abstract

State-of-the-art video compression technologies, such as MPEG-4 AVC/H.264 or the new HEVC standard being developed by ISO MPEG and ITU-T VCEG, make use of tree-structured block partitioning for motion compensation. Such motion partitioning only captures horizontal and vertical motion boundaries. To better match actual motion frontiers, Geometry adaptive block partitioning (GEO) has been explored for several years. GEO enables splitting a block using non-horizontal or non-vertical line. Although noticeable coding efficiency gains can be obtained, GEO involves a significant increase of the number of modes to be tested with therefore a high impact on encoding complexity. This paper presents fast algorithms aiming at controlling the complexity while saving the coding efficiency gains of GEO. Experimental results are provided on top of the HEVC standard, demonstrating first the efficiency of the GEO tool. Simplified versions, offering noticeable complexity reduction with limited rate-distortion performance loss, are also demonstrated and compared.