Video Decoding Performance and Requirements for XR Applications

Designing XR applications creates challenges regarding the performance and the scaling of media decoding operations, composition and synchronization of the various assets. Going beyond the single decoder paradigm of conventional video applications, XR applications tend to compose more and more visual streams such as 2D video assets but also textures and 2D/3D graphics encoded in video streams. All this demands a robust and predictable decoder management and a dynamic buffer organization. However, the behaviour of multiple decoder instances running in parallel is yet to be well understood on mobile platforms. To this end, we present in this paper VidBench - a parallel video decoding performance measurement tool for mobile Android devices. With VidBench, we quantify the challenges for applications using parallel video decoding pipelines with objective measurements and subjectively, we illustrate the current state of decoding multiple media streams and the possible visual artefacts resulting from unmanaged parallel video pipelines. Test results provide hints on the feasibility and the potential performance gain of using technologies like the MPEG-I Part 13 - Video Decoding Interface for immersive media (VDI) to alleviate those problems. We briefly present the main goals of VDI, standardised by the SC29 WG3 Moving Picture Experts Group (MPEG) Systems, which introduces functions and related constraints for optimizing such decoding instances as well as relevant video decoding APIs on which VDI is building upon such as the Khronos Vulkan Video extension.