视频通信基础知识

视频通信基础知识及组网,议程,视频通信的基本概念视频通信网络的组成视频通信标准H.320视频通信系统组网H.323视频通信系统组网,视频通信的基本概念,VideoConference视频会议视讯会议电视会议会议电视电视电话会议,VideoCommunication视频通信,会议,音频视频数据,虚拟会议多方参加不同地点同一会议,“Howmuchisunderstood?”,Communicationmethod,100%,0%,Insomesituations,over90%oftheinformationwegainfromotherpeopleisunspoken.,远程会议,远程教育,远程医疗,远程监控,发送和接收活动视频,Capture（捕捉图像）Digitise（数字化）Analyse（分析需要传送的部分）Coding（编码）Transmission（通过网络传送）Decoding（解码）Display（显示）,关键词,TheDIGITALworld（数字化）CODEC（编解码器）TransmissionBANDWIDTH（带宽）PictureRESOLUTION（图像分辨率）FRAMERATE（帧率）,数字化,0011100010001111010010010101101010101000101110101010001010100001010101010101010101010101010101010101010101010101010100100001111110010101,CODEC,Formatting48,56,or64kbpsG.7227kHzbandwidth;48,56,64kbpsG.722.1TruevoiceCompressedCompressedwideband7KHzrequiring24or32KbsG.723(“IPaudio”)3kHzbandwidth;5.3or6.3kbpsG.7283kHzbandwidth;16kbpsG.7293kHzbandwidth;8kbps,CompositeVideo/S-VHSvideo,WehavetwodifferentwayofsendingoutavideosignalS-VHSvideoCompositevideo,S-VHS,Composite,S-VHSvideosignal,TheplugforS-VHSsignalhas4pins2pinsfortheLuminancesignal2pinsforthecolourvideo(Crominance)signal,Crominancesignal,Luminancesignal,Compositevideo,OneoutputforvideoRCAplugtypeVideosignalisacombinationofCrominanceandtheLuminancesignal,DataStandards,T.120isumbrellastandardforcollaborationNeverreallytookoffwasntinteroperablebetweensoftwareEx:MicrosoftdidntworkwithIntelWebcollaborationandothermeanshavesupercededT.120therearebetterways,H.320视频通信系统组网,H.320CODEC,MCU,MCUReceivesaudio,videoanddatafromendpointsMixesaudioSelectsvideosourceTransmitsconferenceaudioandvideotoendpoints,VideoH.261H.263H.264,DataT.120,AudioG.711G.722G.728,MultiplexingH.221,ControlsignalingH.242H.243H.230,NetworkInterfacesV.xxX.xxI.xx,LineProtocolsI.361I.363I.400,H.320,视频通信标准H.320,H.320ConferencingStandards,MCU,H.231H.242H.230,H.221frame,H.221frame,H.221frame,H.221frame,H.221frame,H.221frame,Audio,Video,2x64kbpschannels,1x384kbpschannel,CommunicationStandards,H.221FramestructureCombinesaudio,videoandcontrol(H.230),CommunicationStandards,H.230ControlandIndicationsignalsH.242EstablishconnectionbetweenendpointsEstablishcommonoperatingparameters(Capabilities)Conveychangesinoperatingparameters,MultipointCommunicationStandards,H.231DefinesMultipointControlUnitfunctionsH.243DefinesproceduresformultipointcommunicationChaircontrolCascadingMCUs,电路交换网络,带宽有保证带宽独占网络服务ISDNBRIISDNPRIDDNT1/E1LeaseLineFrameRelayATM,DDN,H.320Terminals,H.323Terminals,H.320Terminals,Gateway,H.320Terminals,N*BRI,N*BRI,PRI,N*E1,E1,E1,E1,MCU,V.35,V.35,V.35,H.320视频通信网络,ISDNBRI,BChannel,BChannel,DChannel,Supporttwo64kbpsBchannels(Bearerchannels)usedforcarryinginformationUsesone16kbpsDchannel(Deltachannel)usedforcallsetup&callsignaling(aftercallissetup),ISDNPRI,T1,Supports30(23)64KbpsB(Bearer)ChannelsUsesoneOut-of-Band,64KbpsD(Delta)Channelforsignaling,DChannel,ISDNconnectivity,TerminalEquipment(userside),(networkside),NT1,NT,NT1,NT2,Sinterface,Uinterface,Tinterface,TE,TE,ISDNCentralOffice,4wire,2wire,ExampleofanISDNset-up,ISDNNetwork,TANDBERGcodecs&SoftMux(inbuilt),4ISDNlines,PABX,PRI,ISDN,InverseMultiplexing,IMUXMakesasinglehighspeedconnectionfrommultiple64Kbpschannels12maximum,BONDING,BandwidthONDemandInteroperabilityGroup,HowBondingWorks,No.1dialsupwith1xB1channel,TANDBERG6000No.1,TANDBERG6000No.2,No.2AnswerbackwithISDNnumbers,No.1DialchannelsreceivedfromNo.2,InverseMultiplexing,BondingMode0,1,2,3Mode1MultipleofchannelratesNoin-bandmonitoringUsedforH.320Mode3Mode1within-bandmonitoring,T1/E1LeasedLine,StillusedfordedicatedcircuitsProvides24x64kbpschannelsalwaysavailableRequiresCSU/DSUorMuxtobreakoutchannels,NailedupT1,CSU/DSU,CSU/DSU,T1/E1,T1andE1NetworkServices,T124UserChannels64Kbpsperchannel8kbpscontrolchannel1.544Mbps2-pairinterface,E130UserChannels64Kbpsperchannel2controlchannelsat64Kbps2.048Mbps2-pairorcoaxinterface,SerialConnections,V.35,RS-449,RS-530UsedtoconnecttoexternalcommunicationsdevicessuchasT1muxes,satellitemodems,ATMadapters,etc.RS-366dialingprotocolPassesdialingstringtoexternalcommunicationsdevices,FRAMERELAY和ATM,FRAMERELAY通过FRAD设备连接H.320视频通信终端，一般使用V.35接口ATM通过PVC电路仿真连接H.320视频通信终端，使用V.35接口或E1接口H.321视频通信（已很少使用）,V.35,中央卫星网管,卫星视频通信（H.331协议）,V.35,V.35,V.35,发站,收站,H.323视频通信系统组网,IP,InternetProtocolBasiccommunicationlanguageUnreliable,connectionlesspacketdeliveryserviceUnidirectioncommunicationpath,TCP,TransmissionControlProtocolHigherlevelcommunicationlanguageProvidesareliable,connectionoriented,duplexcommunicationpathbetweendevicesGenerallyusesIPasadeliveryserviceUsedbyH.323forControlmessagesandT.120data,UDP,UserDatagramProtocolHigherlevelcommunicationlanguageProvidesasimple,connectionless,duplexcommunicationpathbetweendevicesGenerallyusesIPasadeliveryserviceUsedbyH.323foraudioandvideo,RTP,RealTimeProtocolEnhancementtoUDPSupportsReal-timetrafficAddstimestamp,sequencenumber,andidentificationinformationUsedbyH.323foraudioandvideosignals,RTCP,RealTimeControlProtocolDynamicfeedbacktoRTPAllowsareceivingEndpointtoalterthewayatransmittingEndpointsendstheinformationEnablesSourceQuenching,视频通信标准H.323,H.323,Gatekeeper,Audio&VideoControl,AudioVideo,Data,ConferenceControl,协议栈结构,H.225/Q.931,H.245,T.120,RTP,RTCP,H.225/RAS,TCP,UDP,IP,终端网闸(Gatekeeper)MCU网关(Gateway),H.323视频通信网络的组成,VideoCommunicationnetworks,IPPhones,H.320RoomSystem,Proxy,H.323RoomSystem,Gatekeeper,IPPhones,Router,DesktopVideo,PSTN/ISDN,IPLAN/WAN,MCU,CallManager,IP/TV,VideoGateway,Router,H.323CODEC,Gatekeeper,CallprocessingUserRegistrationandAuthorizationAddresstranslationCallauthorizationBandwidthmanagementEventLoggingandCallAccountingProvidessupplementaryservices,H.323Zones,ControlStandards,H.225Principle“language”oftheGatekeeperQ.931CallsetupandcontrolRegistration,Admission,Statusfunctions,H.225/Q.931/RAS,H.225/Q.931/RAS,H.225/Q.931,H.225Registration,AnEndpointmustRegisterwithaGatekeeperMustregisterwithonegatekeeperonlyConfiguredinEndpointand/orGatekeeper,“Hello,mynameisMary”,H.225Admission,TheGatekeeperwillallowanEndpointAdmissiontoaconferenceBandwidthandsecuritycontrols,“IwouldliketotalktoMaryat400kbps”,Isheallowedto?Isthereenoughcapacity?Canweagreeoncapacity?,H.225Status,TheGatekeeperwillmonitortheStatusofeverythingitcontrolsSends“KeepAlive”messagetoallregisteredEndpointsReceives“KeepAlive”messagesfromcalls,“AreyoustillthereMary”,“AreyoustillthereHarry”,ControlStandards,H.245ConferenceControlUsesaseparatelogicalchannelbetweenEndpointstocontrolaconferencecallEstablishesMaintainsTerminates,GateKeeperRoutedCall,H.245ConferenceControlControlchanneliscontrolledandrelayedbyGatekeeperbetweenendpoints,Control,Audio,Video,Control,2.CanIcall“Jeff”,Chris,1.Hi-mynameis“Chris”,EndpointregisterswithGatekeeperRequestspermissiontoconnect,GatekeeperNon-RoutedCall,Chris,3.Youmay,4.Hisaddressis111.13.43.1,Gatekeeperacceptsrequest(ornot)Returnsaddressofrequireddestination,GatekeeperNon-RoutedCall,Chris,Jeff,5.Hello111.13.43.1AreyouJeff?,6.CanItalktoChris?,7.Yes,8.HelloChris,EndpointconnectstodestinationDestinationcheckswithgatekeeperConnectionMade,GatekeeperNon-RoutedCall,Chris,Jeff,VideoAudioData,AdditionalmediachannelswillbeestablishedConferencecontinuesGatekeeperwatches,GatekeeperNon-RoutedCall,Chris,Jeff,VideoAudioData,Gatekeeperacceptsrequest(ornot)ReturnsaddressofrequireddestinationEndpointconnectstodestinationDestinationcheckswithgatekeeperConnectionMade,GatekeeperNon-RoutedCall,GatekeeperRoutedCall,LegendQ.931RASH.245RTP,Gatekeeper2IP151.67.3.62,Gatekeeper1IP151.67.7.34,1.Call“Mary”,2.Whereis“Mary”?,3.Maryisregisteredwithme,Gatekeeper1IP151.67.7.34,Gatekeeper2IP151.67.3.62,3.Maryisregisteredwithme,5.Connectto151.67.7.34,4.Call“Mary”,UsetheGatekeepersaddress,LegendQ.931RASH.245RTP,GatekeeperRoutedCall,8.Calling151.67.3.11callfor“Mary”,7.Calling151.67.3.62callfor“Mary”,6.Calling151.67.7.34callfor“Mary”,Gatekeeper1IP151.67.7.34,Gatekeeper2IP151.67.3.62,LegendQ.931RASH.245RTP,GatekeeperRoutedCall,Gatekeeper1IP151.67.7.34,Gatekeeper2IP1