在P2P隨選視訊(Video on Demand，VoD)的服務中，每個節點須提供一儲存空間來存放播放過的影音資料，以便將影音資料分享給其他節點。對於輕量化設備如智慧型手機、平板電腦、機上盒等， 其儲存空間不如電腦充裕，能儲存的影音資料有限。使用P2P傳輸時， 當節點發現鄰近節點所擁有的影音資料不足，就會向影音伺服器要求資料，進而增加伺服器端頻寬負擔，也降低了P2P的分享效益。本文提出一P2P VoD儲存控制技術，在輕量化設備中，根據節點的分享狀態來調整一最佳影音儲存率， 使被儲存的影音資料可以有效率地分享給其他節點， 並達到：1)降低影音伺服器的頻寬負擔， 2)分散式執行，降低系統複雜度之優點。我們的實驗結果顯示， 本文提出的方法在有限的儲存空間限制下，可降低30%的影音伺服器頻寬負擔。

In P2P Video-on-Demand (VoD) services, each peer contributes its storage space to replicate the played video data that can be shared to other peers in the P2P network. However, the storage size of lightweight devices, such as: smart phone, tablet computer, set-up box, etc., is less than that of personal computer so that the lightweight devices can only store a limited size of video data. When peers cannot find the required video data from their neighboring peers, they will fetch the video data directly from the content server. Hence, the bandwidth of video server is consumed quickly and the efficiency of P2P network decreases. In this paper, we propose a P2P VoD replication scheme to reduce the bandwidth consumption of video server. Peers can adaptively replicate the video data into the limited storage space by a replication ratio. A replication algorithm is developed to determine an optimum replication ratio according to the sharing status of peers. In addition, peers can adapt the replication ratio in a distributed manner, and thus the system overhead will not significantly increase. The experimental results show that our schemes can reduce 30% bandwidth consumption of the content server.