以數位訊號處理器實現視訊會議之即時H.263編解碼與傳輸

Abstract

隨著個人電腦與網際網路的長足進展，如視訊會議等的即時多媒體應用發展已漸趨成熟。本論文提出一包含桌上型電腦與DSP卡的合作型架構以實現簡單而可擴充的即時視訊會議系統。我們借重DSP卡所具備的高速運算能力，處理系統中即時影像編碼的複雜運算。電腦則扮演系統的主控中心，負責各種介面的規劃運作。本論文討論電腦與DSP卡的合作模式與實現。而視訊會議系統的輸入是數位攝影機即時擷取的影像，經過編碼後，再由網路傳送給遠端接收者。關於即時影像擷取與網路傳輸的特徵性質，本論文由實作的角度探討高效率的實現方法。為了使系統效率達到最佳化，輸出入與編碼這三項動作必須以管線化的模式運作。在電腦的系統程式中我們引入多工同步的機制以實現軟體管線化架構，以此架構改良後的系統效率與硬體使用率皆大幅提升。

With the significant advances in of desktop CPU and internet technology, realtime multimedia applications such as videoconfe-rencing has become feasible and attract much attention. In this thesis, we propose a collaborative structure to implement a simplified and scalable conferencing system. Desktop PC acts as the central control, and a DSP-embedded card is employed as an external, flexible, efficient and scalable computation power to process realtime video encoding. The mechanism and implemen-tation of cooperation of PC and DSP is discussed. The input of conferencing system is realtime captured video frames, and the encoded frames are sent out to client via an IP network. We discuss the implementation of the input and output of the conferencing system. Moreover, in order to further enhance system efficiency, multithreading design is adopted in the central control block and is responsible for construction of system pipelining. We discuss the design methodology of software pipelining. Experimental results demonstrates its ability to improve the system performance. (2)video capturing (3)dsp and pc collaboration (4)network interface (5)multitasking system