We present an evolutionary framework for provisioning enhanced network-based multimedia distribution services to a diverse set of receivers. The framework addresses various degrees of heterogeneity among “distribution paths” from content sources to receivers, where a distribution path carries information from a content-aware multicast distribution tree from a source to one or more receivers. The heterogeneity is characterized by a spectrum of tradeoffs among receiver/client processing capabilities, network conditions, and media representations of desired content. Our goal is to provide individual receivers with the best feasible quality and representation of subscribed multimedia content by efficiently generating distribution paths suiting groups of receivers as they join a multicast. Toward this end, the framework utilizes several evolutionary measures. First, we introduce explicit awareness of receiver capabilities (e.g., bandwidth, CPU processing power) and link characteristics (e.g., loss rat e, error rate) into the network. Second, we decouple media content from its representation to allow the network to generate and distribute multiple representations for the same content. Last, we model the distribution of content from sources to receivers as a relay across multiple content-aware intermediaries that cooperate to overlay a programmable multimedia network on the underlying packet-switched network. The multimedia overlay network thus formed provides sophisticated content-based programmability over the provisioning, routing, and management of media flows. Realization of such a multimedia overlay network requires extensions to existing Internet multicast and resource-provisioning technologies.
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