Video codec is the core engine which has been driving various video related applications for the past several decades, such as online video streaming and video conferencing. Driven by the drastic growth of global video traffic and improved computation power of various devices, the evolution of video compression technology has delivered several generations of video coding standards. In this paper, the technologies used in recent video codecs are described and their coding performance are compared, including HEVC and VVC developed by the ISO/IEC MPEG and ITU-T VCEG, VP9 developed by Google, AV1 developed by AOM and AVS3 (IEEE 1857) developed by Audio Video coding Standard workgroup of China. The datasets cover a wide range of typically used video resolutions up to 4K. The experiments are performed by collecting four data points for each test sequence, and the coding efficiency is measured by the popular BD-Rate metrics.
This paper provides a technical overview of the most probable modes (MPM)-based multiple reference line (M-MRL) intra-picture prediction that was adopted into the Versatile Video Coding (VVC) standard draft at the 12th JVET meeting. M-MRL applies not only the nearest reference line but also farther reference lines to MPMs for intra-picture prediction. The highlighted aspects of the adopted M-MRL scheme include the signaling of the reference line index, discontinuous reference lines, the reference sample construction and prediction for farther reference lines, and the joint reference line and intra mode decisions at encoder side. Experimental results are provided to evaluate the performance of M-MRL on top of the VVC test model VTM-2.0.1 together with an analysis of discontinuous reference lines. The presented M-MRL provides 0.5% bitrate savings for an all intra and 0.2% for a random access configuration on average.