Authors: L. Toni, T. Maugey, P. Frossard
Title: Optimized Packet Scheduling in Multiview Video Navigation Systems, accepted in IEEE Transactions on Multimedia (J12)
Abstract: In multiview video systems, multiple cameras generally acquire the same scene from different perspectives, such that users have the possibility to select their preferred viewpoint. This results in large amounts of highly redundant data, which needs to be properly handled during encoding and transmission over resource-constrained channels. In this work, we study coding and transmission strategies in mul- ticamera systems, where correlated sources send data through a bottleneck channel to a central server, which eventually transmits views to different interactive users. We propose a dynamic navigation-path aware packet scheduling optimization under delay, bandwidth, and interactivity constraints aimed at optimizing the quality-of-experience of interactive users. In particular, the scene distortion is minimized while also the distortion variations along most likely navigation paths is minimized. The optimization relies both on a novel rate-distortion model, which captures the importance of each view in the scene reconstruction, and on an objective function that optimizes resources based on a client navigation model. The latter takes into account the distortion experienced by interactive clients as well as the distortion variations that might be observed by clients during multiview navigation. We solve the scheduling problem with a novel trellis-based solution, which permits to formally decompose the multivariate optimization problem thereby significantly reducing the computation complexity. Simulation results show the gain of the proposed algorithm compared to baseline scheduling policies. More in details, we show the gain offered by our dynamic scheduling policy compared to static camera allocation strategies and to schemes with constant coding strategies. Finally, we show that the best scheduling policy consistently adapts to the most likely user navigation path and that it minimizes distortion variations that can be very disturbing for users in traditional navigation systems.