點對點實況及移時播放之影音服務

Abstract

近年來，P2P應用服務是網際網路最普遍應用；P2P應用吸引了龐大的使用群，也使用最多的網際網路頻寬。主要P2P應用從早期的檔案分享，影音通訊(如Skype)，到目前的影音串流(streaming)服務。本計畫因應P2P網際網路應用發展趨勢，擬設計開發一支援實況（live）與移時（time-shifted）串流影音服務之P2P系統。目前在學術研究與業界雖然已有P2P實況串流(live streaming)系統，或P2P VoD (Video on demand)系統，但並不存在同時支援實況及移時播放的P2P影音串流系統。從現有P2P實況串流系統之瓶頸多在節點上傳頻寬。因此要同時支援實況及移時P2P影音串流，必須有更有效率的利用節點的上傳頻寬。本計畫將先以數學分析此一系統的可行性，並設計開發一有效率的P2P實況與移時串流影音服務系統。工作項目及研究議題如下： 1. 以數學模式分析同時支援實況與移時串流之P2P媒體播送之可行性。針對影音資料儲存空間管理，上傳頻寬限制，以及DVR節點對系統可行性之影響。 2. 設計並開發一適合實況與移時串流之P2P媒體播送系統。主要的設計議題包含：實況與移時群組之管理，移時影音資料之儲存/搜尋/先取策略，以及實況串流和移時串流之傳送架構和傳送排程。並量測系統參數，評估系統效能。 本計畫將深入探討P2P實況與移時串流服務的設計議題，並設計開發一整合P2P實況與移時串流服務平台。此一P2P應用提升現有P2P串流服務功能，深具實用價值。

In recent years, P2P applications have become the most popular applications on the Internet. P2P applications have attracted the majority of Internet users and occupied most of the Internet bandwidth. The popular P2P applications include file sharing, Internet communications (such as, Skype), and most recently, video streaming services. In this two-year project, we will design and develop a P2P video streaming system that supports both live and time-shifted streaming services. Although there are a number of P2P live streaming systems and P2P VoD (video on demand) systems, there is no P2P system that supports both live and time-shifted streaming. The performance measurements of existing P2P live streaming systems indicate that the system bottleneck is the uplink bandwidth limitation of the peers. To support both live and time-shifted streaming, we need to develop a more uplink-efficient video streaming/sharing scheme. The two major tasks of this project are described as follows. 1. The feasibility of P2P live and time-shifted streaming service will be analyzed using stochastic process in terms of video availability, and uplink bandwidth requirements of the peers. 2. Design and develop an efficient P2P live and time-shifted streaming system. Investigate design issues including live/time-shifted group management, time-shifted video caching/searching/prefetching strategies, and video data request/transmission scheduling. The operational data will also be collected to analyze the system performance. In summary, we will investigate the design issues of P2P live and time-shifted streaming services, and develop a P2P live and time-shifted streaming system. Such a system represents a novel application on the Internet and may be of large commercial interests.