Open GOP Resolution Switching in HTTP Adaptive Streaming with VVC

TL;DR

This paper introduces a constrained encoding method for open GOP resolution switching in VVC-based HTTP streaming, achieving significant BD-rate reductions and enabling efficient adaptive streaming with open GOP structures.

Contribution

It enables the use of RPR in VVC for HTTP streaming by analyzing drift potential and proposing a constrained encoding method, improving coding efficiency.

Findings

-8.57% BD-rate reduction in live streaming scenarios

-1.89% BD-rate reduction in VOD scenarios

0.65% BD-rate penalty in worst case

Abstract

The user experience in adaptive HTTP streaming relies on offering bitrate ladders with suitable operation points for all users and typically involves multiple resolutions. While open GOP coding structures are generally known to provide substantial coding efficiency benefit, their use in HTTP streaming has been precluded through lacking support of reference picture resampling (RPR) in AVC and HEVC. The newly emerging Versatile Video Coding (VVC) standard supports RPR, but only conversational scenarios were primarily investigated during the design of VVC. This paper aims at enabling usage of RPR in HTTP streaming scenarios through analysing the drift potential of VVC coding tools and presenting a constrained encoding method that avoids severe drift artefacts in resolution switching with open GOP coding in VVC. In typical live streaming configurations, the presented method achieves -8.57% BD-rate reduction compared to closed GOP coding while in a typical Video on Demand configuration, -1.89% BD-rate reduction is reported. The constraints penalty compared to regular open GOP coding is 0.65% BD-rate in the worst case. The presented method was integrated into the publicly available open source VVC encoder VVenC v0.3.