https://scholars.lib.ntu.edu.tw/handle/123456789/122273
Title: | 子計畫二:能監控服務品質之轉碼技術研發(1/3) | Authors: | 陳銘憲 | Keywords: | 多媒體文件;轉碼伺服器;背包問題;動態規劃;Multimedia documents;Transcoding Proxy;0-1 Knapsack Problem;Dynamic Programming | Issue Date: | 30-Sep-2005 | Publisher: | 臺北市:國立臺灣大學電信工程學研究所 | Abstract: | 本計畫為整合型計畫「多媒體共 享之網路服務平台」之子計畫。其名 稱為「能監控服務品質之轉碼伺服器 技術研發」。在第一年度中,我們參考 了有線及無線網路流量的模型,以及 傳統轉碼伺服器的技術,而設計出適 合處理多媒體文件的轉碼伺服器的架 構,而根據此一架構,我們並將此一 轉碼伺服器處理多媒體文件的機制, 轉化為傳統演算法中,最具複雜度之 困難問題之一,即所謂之「0-1 背包 問題」 (0-1 Knapsack Problem)。此 一問題,在演算法中,最困難之處在 於,用背包在裝物件時,該物件具備 「不可分割」的特性,因此,為了求 出最佳解,我們設計了一套利用「動 態規劃法」(Dynamic Programming)概 念的演算法,藉由這套演算法,我們 可以決定出,轉碼伺服器在處理某個 特定的多媒體文件時,該如何進行「轉 碼」,或是將其存放在伺服器中的「快 取磁碟機」中,使得無線網路的用戶 端,在從轉碼伺服器要求多媒體文件 時,能讓平均等候時間降至最低,而 讓用戶端享有更好的服務品質。 This report belongs to the sub-project “A QoS-Aware Transcoding Proxy using On-Demand Broadcasting”, which is under the integrated project “Design of Service Platform for Sharing Multimedia Documents”. In the first year, we have designed an effective architecture of a transcoding proxy for multimedia documents according to the network flow model in the wired and wireless environment. It is noted that the transcoding technique is capable of trading of object fidelity for size. Therefore, the transcoding proxy for multimedia objects can utilize the network bandwidth very well. According this architecture, we also transform the problem of caching multimedia documents to a “0-1 Knapsack Problem”, which is a well-known NP-Complete problem. According to the characteristics of the problem, we have designed an effective algorithm by using the concept of “Dynamic Programming” so that the problem can be solved in polynomial time. Therefore, a transcoding proxy for multimedia object can perform “transcoding” or “caching” mechanism so as to enhance the quality of mobile users by reducing the average waiting time to the minimum. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/20322 | Other Identifiers: | 932213E002126 | Rights: | 國立臺灣大學電信工程學研究所 |
Appears in Collections: | 電信工程學研究所 |
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932213E002126.pdf | 235.51 kB | Adobe PDF | View/Open |
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