Reactive and proactive approaches to media streaming: from scalable coding to content delivery networks

For an end-to-end media streaming system, the Internet can be considered a back box in the middle that connects a client at one end to the server at the other end. We present both ends' views of the streaming problems and review two approaches to these problems. The first approach, which is represented by scalable coding, is reactive in nature because it seeks to best adapt to changing network conditions such as bandwidth fluctuation and packet loss. The reactive approach is helpful in keeping a steam uninterrupted and proving a graceful degradation, but offers no guarantee on quality of the streamed content and does not help solve server-side problems such as scalability. The other approach is proactive and has motivated recent development in content delivery network. We show that a content delivery network helps improve quality and scalability of streaming, and can be complemented with a reactive approach like scalable coding.