Accelerating the CU partitioning decision in an HEVC-JEM transcoder

Abstract

High Efficiency Video Coding (HEVC) is currently the latest video coding standard available on the market, and it is able to offer up to twice the coding efficiency, in the range of 50% bitrate reduction for the same video quality, of the previous standard, namely H.264/Advanced Video Coding (AVC). HEVC was standardized in 2013 for videos up to a resolution of 2K. However, the popularity of 4K videos is increasing due to the growing use of video-on-demand platforms. Therefore, the ITU-T Video Coding Expert Group (VCEG) and the ISO/IEC Moving Picture Expert Group (MPEG) created the Joint Video Exploration Team (JVET) in 2015 to design the future video coding technology under the Joint Exploration Model (JEM), which its latest version achieves an improvement in coding efficiency of 30%, but at a high cost in terms of computational complexity (10×) with respect to HEVC. The new video standard is expected to be ready in 2020, so it is necessary to find efficient mechanisms to convert current content to the new format adopted in JEM. In this regard, our proposal consists in a probabilistic classifier based on Naive-Bayes that enables the prediction of the splitting decision at the first quadtree level in JEM, reducing the computational complexity of the transcoding process from HEVC to this new standard. The experimental results show a good trade-off between coding efficiency and complexity compared with the anchor transcoder, obtaining a time reduction up to 12.71% at the expense of low coding efficiency penalties in the configurations evaluated.