Intra Prediction Using Multiple Reference Lines for the Versatile Video Coding Standard

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.