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1、EmbeddedVOIPSIP-basedResearchandImplementationoftheterminalADissertationSubmittedtoNanjingInstituteofTechnologyFortheAcademicDegreeofBachelorofScienceBySupervisedbyInstructorCollegeofCommunicationEngineeringNanjingInstituteofTechnologyJUNE2011摘要随着计算机
2、技术和网络技术的发展,语音压缩和实时传输控制技术的不断发展,使得在IP网上传输语音数据变得不再闲难。VoIP是指利用IP网络传送话音的技术,也称网络电话或IP电话。在多媒体技术和网络互连技术的推动下,VoIP技术诞生虽然时间很短,但发展迅猛。同时,随着嵌入式技术的不断发展,嵌入式技术从过去工业控制的应用模式逐步渗透进入消费电子产业。嵌入式VoIP终端作为嵌入式技术与VoIP技术的结合,有着广阔的发展前景。论文首先概要介绍了VoIP的发展现状和前景,研究了基于S1P的信令技术、实时传输技术和媒体协
3、商技术;然后详细阐述了Linux系统基础上终端应用层的实现思想和具体架构,其中包括用于控制信令的SIP模块、用于处理语音的语音模块和用于网络传输的RTP模块。在信令控制部分,在研究并分析开源oSIP协议栈的事务状态机模型的基础上,解决了信令控制问题。在语咅信号处理和数据包传输部分,主要研究并分析了开源MediastreamerI办议栈的实时语音传输T作流程。模拟测试结果显示,设计并实现的嵌入式VoIP终端可以对S1P信令进行很好地控制,具有良好的互通性。关键字:SIP;嵌入式Linux;VoIP
4、;RTP;ARMAbstractWiththedevelopmentofcomputertechnologyandnetworktechnology,voicecompressionandreal-timetransmissioncontroltechnologycontinuestoevolve,makingtheInternettotransmitvoicedatainIPbecomesnolongerdifficult.VOIP,alsocalledIPphone,isatechnolog
5、ythattransmitsvoiceinpacket-switchingnet.Withthetechnologyevolutionofmultimediaandnetwork,VoIPtechnologyadvancerapidly.Atthesametime,withthedevelopmentofembeddedtechnology,embeddedproductshaveextendedfromtraditionalindustryfieldtoconsumingelectronics
6、.Asthecombinationofbothtechnologies,EmbeddedVoIPterminalwillconsequentiallyhavegreatfuture.Firstly,VoIP'scurrentandfuturestatesareoverviewedinthisdissertation.AndthesignalingtechnologybasedontheSIRtherealtimetransporttechnologyandsessiondescriptionte
7、chnologyisdiscussedandanalyzed・Secondly,theapplicationarchitectureandrealizationoftheembeddedterminalbaseonLinuxsystemisdiscussed,whichcontainSIPmodule(signalingcontroller),RTPmodule(voicetransmitter)andvoicemodule(voiceprocessor).IntheSIPmodule,thed
8、ifficultyofsignalingcontrolissettledafterstudyingandanalyzingtransactionstatemachineofoSIP.InRTPandVoicemodules,theopensourcerealtimestreammedialibrary(Mediastreamer)isdevotedtoworktheflowofprocessingandtransmittingofvoicedata.Aftertesting,thetermina