A Scalable and Reliable Paradigm for Media on Demand

  • Authors:
  • Gavin B. Horn;Per Knudsgaard;Soren B. Lassen;Michael Luby;Jens Eilstrup Rasmussen

  • Affiliations:
  • -;-;-;-;-

  • Venue:
  • Computer
  • Year:
  • 2001

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Abstract

The challenges for streaming media today include the high data rates and significant bandwidth required for the uninterrupted delivery of high-quality music and video. Building a scalable and reliable system for on-demand and live streaming in this environment has proven difficult.By definition, a media-on-demand system lets clients freely access and play back media without interruption after a given start-up latency. The authors' system keeps the server's outgoing bandwidth independent of the number of clients, and each client behaves independently of other clients.Although most codecs tolerate a certain amount of data loss, a high loss rate can significantly affect playback quality. Even with router assistance to aggregate acknowledgments, for a sufficiently heterogeneous network and a large enough audience, at least one client will lose almost every packet. This requires retransmission, which causes delays and results in massive reception of duplicate packets.The authors' MoD system uses forward error correction codes to recover lost data. FEC uses the same redundant data to allow multiple clients to recover from different packet losses.