An Enhanced Reference Structure For Reference Picture Resampling (RPR) In VVC

Abstract

Reference picture resampling (RPR) is an important feature for real-time communication in Versatile Video Coding, which supports adaptive resolution change without introducing an instantaneous decoder refresh (IDR) or intra random access picture (IRAP). With RPR, considerable coding gain is achieved while bitrate leap still exists. In this paper, an enhanced reference structure for RPR is proposed. First, the high-resolution (HR) references are used to replace the low-resolution (LR) references to provide more accurate prediction. Furthermore, an adaptive decision on the number of HR references kept in RPL is applied to achieve more performance, which utilizes the history information in the current period. Simulation results show about 9% and 5% BD-rate savings on average can be achieved for scaling ratio of 2:1 and 1.5:1 compared to VTM-10.2 under RPR configurations. For sequences with slight motions, the coding gain is up to 20%. Besides, the bitrate explosion in RPR is reduced generally, where over 50% reductions of bitrates at explosion point is observed.