Synchronization of CDN-based collaborative playbacks

Abstract

Collaborative playbacks systems (CPSs) are media on-demand systems that allow a tightly coupled group of remote clients to jointly request, watch and control a streamed multimedia session (or media playback). Although it is a requirement that the view of the media playback is to be synchronized among the clients of the group, currently the available CPSs are only based on best-effort media playback synchronization. This paper proposes a protocol, K-Sync, for the synchronization of collaborative playbacks provided by content delivery networks (CDNs) . In particular, KSync is based on a CDN-driven approach which uses the estimates of the latencies between CDN servers and clients to opportunely delay the transmission of media streams from CDN servers to clients so as to provide the synchronization of the playback view. K-Sync is designed through a variant of the Extended Finite State Machines (EFSM), an effective formalism for modeling distributed multimedia systems. A prototypal Javabased implementation of K-Sync was carried out and validated on a local testbed.