- 學位論文
以MPEG-4為核心之多媒體群體合作應用架構
A Multimedia Collaboration Application Framework Based on MPEG-4 Standard
摘要
隨著寬頻與無線網路基礎建設的高度發展，電腦運算速度、顯示設備與儲存媒介等硬體技術的一日千里，人們透過各類普及運算設備(Pervasive Devices)取得多媒體資訊，並與其他使用者之間互傳訊息、共享資訊甚至進行虛擬會議等應用已經成為趨勢。而以往電腦輔助群組協同工作(Computer Supported Cooperative Work, CSCW)已廣泛地被運用在遠距教學、軍事模擬以及多人連線遊戲等等不同的領域。然而這些系統多半採用侷限於特定應用的封閉標準(例如美國陸軍的模擬系統SIMNET)；或是應用現有技術以符合特定需求(例如以Web技術發展而成的聊天室)，前者缺乏擴充性與互通性，後者則因為遷就現有架構，並不適用於新興的媒體格式或網路技術。本論文將研究開發一個具有擴充性的多媒體群體合作應用架構。透過這個架構，可以簡化開發各類不同的多媒體群體合作系統(Multimedia Collaboration System)的過程。 要成功地發展出一套多媒體群體合作應用架構，有幾項關鍵技術必須加以考量。首先是互動媒體的呈現技術，由於媒體壓縮標準的蓬勃發展，輔以個人化服務的盛行，使得具備高度互動性的複合媒體需求日益增加。其次，網路連線遊戲、視訊會議以及遠距教學等應用的普及，多使用者環境下的同步技術變得相當重要；最後，對多媒體系統開發者而言，可程式化的應用程式介面將加速開發時程並減少開發成本。 基於以上幾點觀察，本論文將利用MPEG-4標準所定義的工具並參考其所提出的應用程式引擎(MPEG-J)以及多人世界(Multi-User World)架構，設計出一個多媒體群體合作應用架構。本論文設計並實作了四項核心模組，分別是：(1)MPEG-4表現引擎，(2)媒體存取層，(3)MPEG-4應用程式引擎以及(4)多人應用程式伺服器。MPEG-4表現引擎是一個跨平台的互動媒體呈現架構，配合用戶以及伺服端的媒體存取層，能滿足多點傳輸媒體資料流的需求。而MPEG-4應用程式引擎提供了一組應用程式介面，外部程式可藉此來存取並操控MPEG-4表現引擎。多人應用程式伺服器則提供了可程式化的伺服端架構，配合與用戶端之間的遠端函式呼叫實現多人連線下的同步機制。 本論文所提出的這套架構，使得程式開發者能快速開發出不同類型的多媒體群體合作系統。為了驗證本架構之適切性，我們開發了「線上室內設計」、「具有三維共享物件之視訊會議」以及「多人連線遊戲」等多媒體群體合作系統。由開發者的經驗可知，本架構確實降低了這些多媒體群體合作系統的開發難度與成本。
並列摘要
Given the rapid deployment of the broadband network and the wireless network infrastructure and drastic improvement in computational power of CPUs, storage media, display devices, and other hardware technologies, people can jointly and collaboratively access, share and create multimedia contents anytime, anywhere through a variety of pervasive devices such as cell phones, PDAs, and PCs. For examples, they can send messages, share multimedia clips, or participate in multi-user virtual meeting through a variety of collaborative applications. In past years, researches on CSCW (Computer Supported Cooperative Work) have been widely adopted to applications of distance learning, military simulation and multiplayer gaming. However, these systems use either proprietary solutions or reform existing technologies to fulfill specified applications. The former is lack of extensibility and interoperability while the latter accommodates the original architecture and is hard to adopt emerging media format or network technology. The goal of this thesis is to design and develop an extensible multimedia collaboration application framework with a core set of common multimedia and collaboration functionalities, so that it can greatly simplify the amount of developers’ efforts in building multimedia collaboration systems. To design and develop the multimedia collaboration application framework, we have identified the following three core technologies that are of critical importance in the framework. (1) Multimedia Presentation: Due to the improvement of coding standards and prevalence of personalized interactive services, the need for a new class of interactive rich-media presentation technology grows. (2) Multi-User Technology: Given the high demand for internet games and distance learning, an efficient synchronization technology is crucial in achieving consistency in multi-user environment. (3) Multimedia Application Development: For the multimedia application developers, a set of programmable application interface and library are needed to reduce their application development time and cost. Based on three core technologies, the thesis attempts to use the tools defined by MPEG-4 to develop a multimedia collaboration application framework. The thesis also considers the application engine and multi-user architecture of MPEG-J and MPEG-4 MUW (Multi-User World) during the developing process. We design and develop four corresponding modules, namely (1) MPEG-4 Presentation Engine, (2) Media Access Layer, (3) MPEG-4 Application Engine, and (4) Multiuser Application Server in our multimedia collaboration framework. MPEG-4 Presentation Engine is based on the design of cross-platform MPEG-4 media presentation architecture, enabling media presentation on heterogeneous terminal devices. Through media access layer residing in both client and server side, a multicasting media service has been realized. MPEG-4 Application Engine exposes a set of APIs for the applications to customize the behavior of the underlying presentation engine. Multiuser Application Server provides a programmable architecture and remote function call mechanisms for clients to provide multi-user synchronization. The thesis provides core functionalities in the framework and allows application developers to develop various Multimedia Collaboration Systems efficiently. To verify the practicability of proposed framework, we have developed a number of systems, including on-line interior design, virtual meeting with shared 3-D objects and multi-user games. Based on the developers’ experience, the framework indeed reduces the application development complexity and cost.