【摘要】：視頻會(huì)議系統(tǒng)是當(dāng)前網(wǎng)絡(luò)視頻應(yīng)用領(lǐng)域最火熱的需求之一。傳統(tǒng)的視頻會(huì)議系統(tǒng)大多基于H.32X協(xié)議族構(gòu)建,IETF工作組提出了SIP協(xié)議作為H.32X的替代,相比之下具有易搭建、擴(kuò)展靈活等優(yōu)點(diǎn)。本文設(shè)計(jì)了一套基于SIP協(xié)議的視頻會(huì)議系統(tǒng)。簡要介紹了SIP協(xié)議的信令格式和網(wǎng)絡(luò)邏輯單元等概念,以及SIP協(xié)議的基本呼叫流程,從整體上對SIP有了一定認(rèn)識(shí)。由于SIP協(xié)議必須要與其它眾多協(xié)議協(xié)同工作,又簡單介紹了SDP協(xié)議、RTP協(xié)議和RTCP協(xié)議等。對視頻會(huì)議系統(tǒng)的拓?fù)浣Y(jié)構(gòu)進(jìn)行了分析,集中式信令流和組播式媒體流拓?fù)涞慕Y(jié)構(gòu)具有較大優(yōu)勢。由于當(dāng)前網(wǎng)絡(luò)環(huán)境中IP組播技術(shù)發(fā)展不夠成熟,因此提出了應(yīng)用層組播技術(shù)代替IP組播進(jìn)行媒體流傳輸。在對比了基于節(jié)點(diǎn)綜合能力的計(jì)算模型和基于RTT平均值的計(jì)算模型兩種節(jié)點(diǎn)可用性計(jì)算方式后,將兩者結(jié)合起來作為本文應(yīng)用層組播樹的構(gòu)建基礎(chǔ),并說明了組播樹維護(hù)過程。在分析視頻會(huì)議系統(tǒng)需求的基礎(chǔ)上,給出了系統(tǒng)的總體結(jié)構(gòu)和各模塊的功能設(shè)計(jì),并結(jié)合SIP協(xié)議與應(yīng)用層組播樹詳細(xì)說明了實(shí)現(xiàn)細(xì)節(jié),從節(jié)點(diǎn)間會(huì)話協(xié)商、會(huì)議功能管理、數(shù)據(jù)傳輸?shù)冉嵌日故玖薙IP信令交換的流程。QoS策略為多媒體應(yīng)用提供網(wǎng)絡(luò)服務(wù)保障,在結(jié)合了RTCP報(bào)文和應(yīng)用層組播樹的傳輸方式上,本文提出了局部擁塞和全局擁塞的概念,并設(shè)計(jì)了完整的擁塞解決方案。最后,以PJSIP和JRTPLIB兩個(gè)開源的框架為基礎(chǔ),對系統(tǒng)進(jìn)行了實(shí)現(xiàn),并在測試中驗(yàn)證了其功能的完整性。
[Abstract]:The video conference system is one of the hottest demands in the field of network video application. Most of the traditional video conferencing systems are based on H.32X protocol family. The SIP protocol is proposed as an alternative to H.32X protocol, which has the advantages of easy to build, flexible extension and so on. This paper designs a video conference system based on SIP protocol. This paper briefly introduces the concepts of signaling format and network logic unit of SIP protocol, and the basic call flow of SIP protocol, and has a certain understanding of SIP as a whole. Since the SIP protocol must work with many other protocols, the SDP protocol and RTCP protocol are briefly introduced. The topology structure of video conference system is analyzed. The structure of centralized signaling flow and multicast media flow has great advantages. Because the IP multicast technology is not mature enough in the current network environment, the application layer multicast technology is proposed to replace IP multicast for media stream transmission. After comparing the two computing methods of node availability based on node synthesis ability and RTT average, this paper combines the two models as the basis of constructing the application layer multicast tree, and explains the maintenance process of the multicast tree. On the basis of analyzing the requirements of videoconferencing system, the overall structure of the system and the function design of each module are given. The implementation details are explained in detail by combining SIP protocol and application layer multicast tree, from the nodes to the session negotiation, the conference function management. From the point of view of data transmission, the flow. QoS policy of SIP signaling exchange provides network service guarantee for multimedia applications. In this paper, the concepts of local congestion and global congestion are proposed in combination with RTCP packets and application layer multicast tree. A complete congestion solution is designed. Finally, based on two open source frameworks, PJSIP and JRTPLIB, the system is implemented, and its functional integrity is verified in the test.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TN948.63

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