目前隨選視訊系統已經逐漸成為實際可用的系統。由於骨幹網路的限制，大多數的隨選視訊系統都是以三層式的架構(Server-Local Server-Client)，透過本地端伺服器來提供服務。藉由影片快取，可以在有限頻寬下提高同時播送的影片數。影片的快取，相較於網頁代理伺服器(Web proxy cache)，它的儲存空間與傳遞時間都較一般網頁物件來得大，這使得一般的快取機制不能有好的效率。特別是配合熱門影片廣播法，以週期性的將影片區段群播給用戶，影片區段快取的管理是非常重要的工作。 我們提出一個有效率的影片快取方法，來建立一個熱門影片廣播法的本地端影片伺服器模型。它的特色是根據影片存取的連續性，在已知的播放法則上，降低將要播送的快取區段的置換率來增加快取區段的命中率，來改善整體用戶透過本地端伺服器到遠端主機的頻道使用數。 The video-on-demand systems have became a pratical system. Because of the bandwidth limit, most of these system are three-tier architecture(Server-Local Server-Client ) for clients service by local server. By way of media stream cache, it can increase the service rate under limited bandwidth. This kind of stream cache, compared with web cache, the stored object are more huge than web object on storage consumption. Traditional cache scheme can't have good performance on the media stream. Especially operating with the hot-video broadcasting scheme, video server periodically broadcast video segments to clients, the cache management becomes very important. We propose a efficient method of video cache of local server for hot-video broadcasting. The characteristic of this scheme are based on clients' sequentially requesting videos, decrease the playing segments' replacement rate and increase cached segments' hit rate to improve average bandwidth consumed from remote server and local server.
