隨選視訊系統之分散式多媒體資源管理

Abstract

隨選視訊服務 (Video On Demand, VOD), 是一種可以讓較少的使用者能夠在其需要之時, 由大量影片中, 選擇到適合他所期望的影片的一種新一代網路服務。雖然廣域網路下的隨選視訊服務尚有許多困難; 但是區域網路技術的進步, 以及其設備價格的降低, 使得小區域的隨選視訊服務成為一種可行的個人化服務。我們先前研製出的有線電視網路控制器 (CNC, Cable Network Controller), 能夠為有線電視網路提供了隨選視訊服務。它是一個低成本、社區規模的區域性網路, 提供了家庭娛樂、遠距教學、社區互動式佈告板... 等各種服務。 在服務個人化的趨勢下, 隨選視訊服務的影片資源數量、影片分類及檢索工作... 等等也成為評估一個隨選視訊系統良莠的重要參數; 即使在網路頻寬品質達成之時, 大量影片資源備妥之時, 若無方便的影片索尋系統, 那麼這個網路應用的品質也將令人質疑。針對此問題, 我們重新對資源的分類方法作分析, 設計一套資源分類管理的目錄系統理論。我們所研究的這套資源管理方式, 包括了目錄系統架構原理、分散式環境、資源交換與共享、以及最重要的, 它提供了分類法的彈性, 它使得管理者能以主題導向的方式, 彈性地去架構其分類模式, 以達到方索尋的目的, 提供有別於傳輸層次的優勢, 使隨選視訊服務更加個人化。

The “Video On Demand” (VOD) is an application of network services, which provides a greate quantity of video titles or interactive television (ITV) programs to people who want it instantly. In our previous researches, we have implemente a VOD service based on cable TV network with very low cost for community-scaled users, we called it “CVOD System”. It guaranteed a very good quality of video and audio transmissions. In the modern trend of service flexibility, the video titles and interactive programs, or say “resources”, reasonably be more and more, to provide a very wide selections for clients. However, also an important criterion to evaluate the quality of VOD service since it is needed to choose the expected resource very efficiently from a large number of resources? We think it is a more important issue than providing a mass of resources, and it is also a criterion to evaluate the quality of VOD service. In this paper, we proposed a design of structure of resources, classification theory, and architecture for the VOD resource management problems. The theory is primarily a “distributed directory system” for any accessible data objects, resources. In the approach we proposed, resource managers could set up a “Multimedia Resource Center” to share resources to each other. More important, resource managers or users might create classification schemes for themselves flexibly; this makes more advantages to VOD systems, and will be the essential part of VOD systems in the future.