2008 Reports

Stored Media Streaming in BitTorrent-like P2P Networks

Hwang, Kyung-Wook; Misra, Vishal; Rubenstein, Daniel Stuart

Peer-to-peer (P2P) networks exist on the Internet today as a popular means of data distribution. However, conventional uses of P2P networking involve distributing stored files for use after the entire file has been downloaded. In this work, we investigate whether P2P networking can be used to provide real-time playback capabilities for stored media. For real-time playback, users should be able to start playback immediately, or almost immediately, after requesting the media and have uninterrupted playback during the download. To achieve this goal, it is critical to efficiently schedule the order in which pieces of the desired media are downloaded. Simply downloading pieces in sequential (earliest-first) order is prone to bottlenecks. Consequently we propose a hybrid of earliest-first and rarest-first scheduling - ensuring high piece diversity while at the same time prioritizing pieces needed to maintain uninterrupted playback. We consider an approach to peer-assisted streaming that is based on BitTorrent. In particular, we show that dynamic adjustment of the probabilities of earliest-first and rarest-first strategies along with utilization of coding techniques promoting higher data diversity, can offer noticeable improvements for real-time playback.