Peer-to-Peer Live Multicast: A Video Perspective

Peer-to-peer multicast is promising for large-scale streaming video distribution over the Internet. Viewers contribute their resources to a peer-to-peer overlay network to act as relays for the media streams, and no dedicated infrastructure is required. As packets are transmitted over long, unreliable multipeer transmission paths, it is particularly challenging to achieve consistently high video quality and low end-to-end delay. In this paper, we focus on error-resilient transport for peer-to-peer video streaming. The algorithms we describe are representative of three broad categories of robust video streaming schemes: forward error correction, multiple descriptions, and prioritized automatic repeat request. We analyze how these techniques can be employed for live peer-to-peer multicast and discuss their relative merits. Our results show that significant gains can be obtained when systems are designed to adapt to the encoding structure of the video streams they are transmitting. They also reveal the importance of avoiding congestion at every peer participating in the multicast to obtain a low-latency system. Finally, we provide insights as to which are the important metrics to compare different peer-to-peer streaming systems.