Building an efficient transcoding overlay for P2P streaming to heterogeneous devices

Abstract

With the increasing deployment of Internet P2P/overlay streaming systems, more and more clients use mobile devices, such as smart phones and PDAs, to access these Internet streaming services. Compared to wired desktops, mobile devices normally have a smaller screen size, a less color depth, and lower bandwidth and thus cannot correctly and effectively render and display the data streamed to desktops. To address this problem, in this paper, we propose PAT (Peer-Assisted Transcoding) to enable effective online transcoding in P2P/overlay streaming. PAT has the following unique features. First, it leverages active peer cooperation without demanding infrastructure support such as transcoding servers. Second, as online transcoding is computationally intensive while the various devices used by participating clients may have limited computing power and related resources (e.g., battery, bandwidth), an additional overlay, called metadata overlay, is constructed to instantly share the intermediate transcoding result of a transcoding procedure with other transcoding nodes to minimize the total computing overhead in the system. The experimental results collected within a realistically simulated testbed show that by consuming 6% extra bandwidth, PAT could save up to 58% CPU cycles for online transcoding.