遍布即時多媒體系統與技術---子計畫六：有線/無線環境上建構於對等連網及內容傳播網之可適性串流技術

Abstract

諸如數位互動電視之多媒體串流服務是一個因應視訊、聲音、資料和網路科技成熟化之自然結合。 然而，一個大規模之多媒體網路服務所需求之大量的網路和伺服器等資源的需求，以及各客戶端 環境的變異性，都加劇了為維持服務品質 (quality of service) 所帶來的系統設計挑戰，也成為這 幾年來日益受矚目之研發重點。另外，在無線通訊的網路通道裡，動態環境的改變經常導致比特 (bit)發生錯誤甚至於封包的遺失，這類的資料遺失或錯誤和因為網路壅塞所導致的封包遺失有很 大的不同，需要不同的機制加以處理；而能因應客戶端環境差異性的分層編碼 (scalable coding) 更 替多媒體串流服務加重了開發者所需考慮之複雜度。本計畫的主要目的，在於建構研發一個結合 內容傳播網 (CDN： content distribution network)和對等連網 (peer-to-peer network) 之可適性串流 技術，並透過聯合分層串流之來源編碼 (source coding) 和通道編碼 (channel coding) 的演算法以 用於在日益普遍之異質有線/無線網路的環境下提供大規模之串流服務，讓每個客戶端依據其獨特 之環境而接收適合之多媒體內容服務。

Multimedia streaming, such as interactive IP television (IPTV), is a natural consequence of global convergence of video/audio/data coding and network technology. However, the massive resource requirements of streaming server and network for a large-scale streaming application impose great challenges for a system designer with quality-of-service in mind. Moreover, in a wireless communication network, dynamic channel fluctuation often causes bit errors and subsequently leads to packet loss, which has distinct characteristics from the packet loss due to network congestion. We have been proposing that different strategies are required for different types of multimedia packet loss that results in performance degradation for efficient streaming. Scalable coding, on the other hand, is a popular research direction to deal with heterogeneous client environments but it certainly complicates the design of streaming system architecture. The objective of this research project is to study and develop a hybrid streaming system based on extended content distribution network and peer-to-peer network to provide load balancing and address scalability issue for a real-time multimedia streaming system. We also plan to study joint source coding, including scalable coding, and channel coding so that each client may acquire appropriate multimedia streaming service according to the dynamic heterogeneous wired/wireless channels.