針對P2P移時串流系統之影音檔案儲存

Abstract

現今的P2P影音串流主要分為實況影音串流和隨選視訊串流，透過P2P的方式來提供影音串流的服務。然而收看實況影音串流的使用者只能收看最新的影音內容，無法收看過去時間的影音內容；收看隨選視訊串流的使用者雖然可以隨自己喜好隨選隨看，但無法收看即時的實況影音。 雖然過去有很多和P2P影音串流的研究，但是目前並還沒有任何研究明確的實作出能支援移時播放的P2P影音串流系統，我們提出一套針對P2P移時串流系統之影音檔案儲存方法，借由這個方法，開發一套支援實況和移時串流的系統，使用者可以依自己喜好來選擇收看實況的影音串流或是移時串流。 在我們的系統中，每個使用者一個短期的儲存器和一個長期的儲存器，我們提出一個演算法來，將短期儲存器內部份的影音內容移至長期的儲存器，除此之外，當要存的影音內容超過我們的儲存器大小時，我們也提出一套合適的替換機制。

P2P multimedia streaming today can be categorized into live streaming and video-on-demand (VoD) streaming; both adopt P2P techniques to provide multimedia streaming services. However, live streaming users can only watch the latest media contents but cannot watch previous ones. Although VoD streaming users can watch what they want at any given time, they cannot watch live media content. Although there are many studies about P2P live streaming and P2P VoD streaming, there are no P2P streaming systems that can provide both live and time-shift streaming at the same time. In this thesis, we propose a storage policy for P2P time-shift streaming contents. Based on the storage policy, we implement a P2P streaming system that can providing time-shift streaming and live streaming at the same time. In our streaming system, each peer maintains a short-term storage and a long-term storage. We propose an algorithm to turn part of media contents in short-term storage to long-term storage. Besides, in order to prevent the size of media content exceed the size of storage; we also propose a replacement policy.