多媒体通信网络（英文版）

Multimedia

CommunicationNetworksObjectivesinEnglishlecture

UseEnglishtolearnadvancedandemergingtechnologies,notanEnglishcourse.GetsomeexperiencesandpracticesofacourselecturedwithEnglish.Thinkandpresentideasdirectlywithoriginalwords.Keepupwithpaceofadvancedgraduateeducation.Firstideas

WhatisMultimedia?Whatarenetworks?Whatarecommunicationnetworks?Whataremultimediacommunicationnet-works?Howdonetworksaddresstherequirementsofmultimediaapplications?Spatio-temporalcharacteristicsArchitecture,protocol,QoSetc.GoalsoftheCourseLearnabout:Basicconceptsandprinciplesofmulti-mediacommunicationnetworksMaintechnologiesandprotocolsneededformultimediacommunicationnetworksfromsystemviewCoveringfromthelowest(physical)layertothehighest(application)layerDiscussimportanttrendsCourseScheduleChapter1Introduction 6Chapter2MultimediaNetworks: 3RequirementsandPerformanceIssuesChapter3SubnetTechnology 6LowerlayersnetworktechnologiesFastLANandATMsubnetFiberchannelWirelesssubnet3G*Accesssubnet:cablemodem,ADSLCourseScheduleChapter4NetworkandTransportlayer 6ProtocolsforMultimediaIPv6,IPmulticastRTP,RSVPQoS

Chapter5MultimediaApplications 6VideoconferencingVoDApplicationsinWWWStreamingAudio/InternetRadio/VoiceoverIP*CourseScheduleChapter6Synchronization 3Intra-andinter-synchronizationformediastreams.*Chapter7CompressionStandard 6MPEG-4/avcH.26L/H.264*JPEG2000*CourseScheduleLecturetime:Thur.5,6,7.1-12weeks.Officetime:Wed.4-5:30pm.At337buildingofInformationSys.&ManagementSchool.PrerequisitesIntroductorycourseonComputerNetworksBasicprinciplesofDataCommunicationBasicoperatingprinciplesofTCP/IPIntroductorycourseonMultimediaTechnologyAssignmentsandExamsExercisestoconsolidateunderstanding:assignmentsprojectsGrading:Assignments:50%Mini-project:50%ReadingsTextbook:MultimediaNetworking:fromtheorytopractice.JenqNengHwang,Cambridgeuniversitypress,2009.MultimediaCommunications:ProtocolsandApplications,FranklinF.Kuoal.PrenticeHallPTR.1998.李国辉等.多媒体通信网络.人民邮电出版社，2010.ReferencesAS.Tanenbaum.ComputerNetworks.PrenticeHallPTR,fourthedition,2003.RalfSteinmetzal.,MultimediaComputing,Communications&Applications,PrenticeHall,1995.ReferencesACMMultimediaConference(firstinAugust1993,Anaheim,CA)IEEEInternationalConferenceonMultimediaandExpo(firstinMay1994,Boston,MA):NowICME.IEEETransactiononMultimediaACMSpringerJournal“MultimediaSystem”IEEEMultimediaMagazineChapter1Introduction1.1MultimediaandNetworks1.2CommunicationNetworks1.3MediaandStreamCharacteristics1.4LayeredArchitectureandMultimedia1.5SummaryChapter1IntroductionISSUESinthischapter1.What’reMultimediaNetworks?2.WhatStreamCharacteristicsarethereinvolvedindigitalmedia?3.WhatMultimediaissuesarethereineachLayerofnetworkingArchitecture?1.1MultimediaandNetworksProblemWhatisMultimedia?WhatistherelationshipbetweenMultimediaandNetworks?1.1MN-WhatisMultimedia?Fromuser’sperspective,Multimediameansthatcomputerinformationcanberepresentedthroughaudioand/orvideo,inadditiontotext,image,graphicsandanimation.Fromthetechnicalperspective,thetimingandintegrationrequirementamongallcomponentsofthemediaisthemajorchallenge.1.1MN-WhatisMultimedia?Continuousmediaindividualrepresentationvaluesoccurasacontinuoussequence,suchasvideoandaudio.Videoisasequenceofimagesoccurringperiodically. Discretemediainformationinthesemediaconsistexclusivelyofasequenceofindividualelementswithouta

timecomponent,suchasimageandgraphics.1.1MN-WhatisMultimedia?Multi-:many;much;multiple.Medium:Aninterveningsubstancethroughwhichsomethingistransmittedorcarriedon;Ameansofmasscommunicationsuchasnewspaper,magazine,ortelevision.

-fromAmericanHeritageElectronicDictionaryameansfordistributionandpresentationofinformation.1.1MN-WhatisMultimedia?Multimediaisanymediaintegratedwithmorethanasinglekindofmedia.Multimediadistinguishesitselffromotherthroughseveralproperties:combinationofmedia(onlywhenboth

continuosanddiscretemediaareutilized)integration(computercontrolled;timing,spatialandsemanticsynchronizationrelationsareincluded.)manipulation(interaction)1.1MN-WhatisMultimedia?Multimedia,strictlyspeaking:

continuousmediawillalwaysbeincluded,andtimelymarginalconditionfortheprocessingofdiscretemediawillbeintroduced.Multimedia,inthebroadersense: Oftenthenotiondescribetheprocessingofindividualimagesandtext,althoughnocontinuousmediumispresent.1.1MN-MultimediaandNetworkMultimediaistheholygrailofnetworking.Nobookonnetworkingwouldbecompletewithoutatleastanintroductiontothesubject(multimedia). -A.S.Tanenbaum,“ComputerNetworks”Multimediacomputingandcommunicationsareareaofintensecurrentinterest,softwareandhardwaredevelopment,Internet,andfuturepromise.1.1MN-MultimediaandNetworkMultimedianetworkingsystemallowsforthedataexchangeofdiscreteandconti-nuousmediaamongcomputers.Thiscommunicationnetworksrequireproperservicesandprotocolsformulti-mediadatatransmission.1.2CommunicationNetworksWhatisCommunicationNetworks?1.2CommunicationNetworksCommunicationnetworksenableuserstotransferinformationintheformofvoice,video,emailandcomputerfiles.Usersrequestservicesbyusingaphonehandset,cellularphone,set-topboxandapplications.Notonlycomputer1.2CommunicationNetworksCommonlyusedcommunicationnetworks:telephonenetworkscomputernetworkscabletelevisionnetworkswirelessnetworks1.2CN-telephonenetworksThekeyinnovationsintelephony?1.2CN-telephonenetworksThekeyinnovationsintelephonyare:Circuitswitching(circuitswitcher)Digitization(PCMcode;DCS-DigitalCarrierSystem,andDS-DigitalSignalHierarchy;e.g.T-1,orE-1line)Separationofcallcontrolfromvoicetransfer(CCS-CommonChannelSignaling)Opticallinks(1980s,->SONETorSynchronousOpticalNetwork;SDH-SynchronousDigitalHierarchy;STS-SynchronousTransferSignal)Serviceintegration(ISDN)1.2CN-telephonenetworksTelephone:18801.2CN-telephonenetworksTelephone:19881.2CN-telephonenetworksTelephone:ISDN1.2CN-computernetworksThekeyinnovationsincomputernetworks?1.2CN-computernetworksThekeyinnovationsincomputernetworks:OrganizationofdatainpacketsPacketswitchingInternetprotocolhierarchy(TCP/IP)Multipleaccessmethods(SharedChannelforLAN)Serviceintegration(B-ISDN;ATM-AsynchronousTransferMode)1.2CN-computernetworksRS-232(serialline)1.2CN-computernetworksSDLC-SynchronousDataLinkControl1.2CN-computernetworksStore-and-Forward1.2CN-computernetworksEthernet1.2CN-computernetworksTokenRing1.2CN-computernetworksFDDI–FiberDistributedDataInterface1.2CN-computernetworksATM–AsynchronousTransferMode1.2CN-cabletelevisionnetworksThekeyinnovationsincableTV?1.2CN-cabletelevisionnetworksThekeyinnovationsincableTVare:Opticalfeederlinks(FTTC:fiber-to-the-curb;orHFC:hybridfiber/coaxial)Digitalcompressiontechniques(MPEG-1;MPEG-2;MPEG-4)Serviceintegration(newservices,suchasVoD,Internetaccess,telephony,etc.;bi-directionalnetwork)1.2CN-cabletelevisionnetworks1.2CN-wirelessnetworksKeyinnovationsinwireless?1.2CN-wirelessnetworksThefirstpacket-switchedwirelessnetwork:ALOHA,1971attheU.ofHawaii.Bandwidthinwirelessnetworksremainsaveryscarceresource.ThechallengeforwirelessnetworkswillbetoprovideconnectivitytotheInternet,integratedservices,especiallyvoiceanddata,aswellasmultimediaandwebaccess.1.2CN-wirelessnetworksKeyinnovationsinwireless:RadioandTVbroadcastCellulartelephonesWirelessLANs(802.11)andadhocBluetoothCellularpackets(GPRS,CDMA),1,2,3GVoice,dataintegration

WiMax(802.16)1.2CN-wirelessnetworksIMT-2000goals(3G)Commonglobalfrequencyband(1.8-2.2GHz)Commonairinterfacesforvehicular(144kbps),pedestrian(384k),indoor(2M),satellite(9.6k)Circuit-switch,packetswitch,multimediaCompatibilitywithfixednetworksGlobalroaming?Whatproposalsaretherefor3Gnow?1.2CN-TrendThedifferencesamongthesetypesofnetworkarestillgreat.However,eachtypeofnetworksisnowabletoprovidetheservicesthatwereformerlytheexclusiveprovinceofothernetworks.Trend:

Convergence!1.3MediaandStreamCharacteristicsWhatcharacteristicsarerelatedwithmediatransmission?Whatdifferenceamongasynchronous,synchronous,isochronoustransmission?WhatarethemeaningsofCBRandVBR?Whydowediscussthosestreamcharacteristics?1.3MediaandStreamCharacteristicsSpecifythemultimedianotionfromthecommunicationpointofview.Transmittedinformationisdividedintoindividualunitsandsubsequentlysentawayfromsourcetodestination.Asequenceofindividualpacketstrans-mittedinatime-dependantfashioniscalledadatastream(dataflow).1.3MediaandStreamCharacteristics Datastreamwithdifferentmediahasdifferentfeatures:traditionaldatastreamscharacteristicscontinuousmediacharacteristicsinformationunits1.3MSC-traditionaldatastreamscharacteristics Thefollowingattributescomefromthefieldsofcomputercommunicationwithrespecttoend-to-enddelayofindividualpacketsAsynchronoustransmissionmodeSynchronoustransmissionmodeIsochronoustransmissionmode1.3MSC-traditionaldatastreamscharacteristicsAsynchronoustransmissionmodecommunicationwithnotimelyrestriction.Packetsreachthereceiverasfastaspossible.e.g.email.Synchronoustransmissionmode

definesamaximumend-to-enddelayforeachpacketofadatastream.Apacketcanreachthereceiveratanyarbitraryearliertime.e.g.videotransmissiononLAN.1.3MSC-traditionaldatastreamscharacteristicsIsochronoustransmissionmodedefinesamaximumandaminimumend-to-end-delayforeachpacketofadatastream.Delayjitterofindividualpacketsisbounded.Q:DifferenceamongAsynchronous/synchronous/isochronous?1.3MSC-continuousmediacharacteristicsAudioandvideodatastreamcharacteristics.1.Timeintervalbetweenconsecutivepacketsstronglyperiodic-thetimeintervalbe-tweentwoconsecutivepacketsisconstant. e.g.PCM-codedspeechintelephoneline.Tt1.3MSC-continuousmediacharacteristicsweaklyperiodic-thedurationofthetimeintervalbetweentwoconsecutivepacketscanbedescribedthroughaperiodicalfunctionwithfiniteperiod,butthetimeintervalisnotconstant. t1.3MSC-continuousmediacharacteristicsAperiodic-allotherpossibilitieswithrespecttotimeinterval.

e.g.Cooperativeapplicationwithsharedwindows.

t1.3MSC-continuousmediacharacteristics2.Variationofconsecutivepacketamountstronglyregular-amountofdatastaysconstantduringthelifetimeofadatastream. e.g.videostreaminuncompressedform. alsocalledCBR(ConstantBitRate)stream.t1.3MSC-continuousmediacharacteristicsweaklyregular-amountofdatavariesperiodicallywithtime. e.g.compressedvideostream,MPEGtT1.3MSC-continuousmediacharacteristicsirregular-amountofdataisneitherconstantnorchangesaccordingtoaperiodicfunction.Acomplicatedcase.

Somecompressionmethodsproducethiskindofirregulardatastream.LasttwocasesarecalledVBRstream.t1.3MSC-continuousmediacharacteristics3.ContiguousnessofpacketsCharacterizecontinuityorconnectionbetweenconsecutivepackets.Areconsecutivepacketstransmitteddirectlyoneafteranother?Isthereagapbetweenthepackets?Thiscanbeseenasutilizationofnetworkresource.1.3MSC-continuousmediacharacteristicsPacketsaretransmittedwithoutagapaB-ChannelofISDNwithtransmissionof64kbpsaudiodataisanexample.100%systemresourceisutilized.Calledconnecteddatastream.t1.3MSC-continuousmediacharacteristicsGapsexistamongthepacketsTransmissionofdatastreamthroughachannelwithahighercapacityleadstogapsbetweenindividualpackets.Calledunconnecteddatasteam.t1.3MSC-continuousmediacharacteristicsQ:continuousmediacharacteristics?1.3MSC-continuousmediacharacteristicsNormally,continuousmediaisweaklyperiodic,weaklyregular,andunconnecteddatastream1.3MSC-informationunitsLogicalDataUnit(LDU):Continuousmediaconsistofatime-dependentsequenceofindividualinformationunits.SuchaninformationunitiscalledLDU.ProtocolDataUnit(PDU):exchangeddataunitsbetweentwopeersthroughaprotocol.ThemeaningoftheLDUandPDUcanbedifferent:LDUforvideo:film,clips,frames,pixels.PDU:canbeanydatablocksorganizedaccordingtotheneedofsource/channelcodingandprotocol.1.3MSC-informationunitsLDUforvideo:film,clips,frames,pixels.FramesShotsScenesAProgram1.3MSC-informationunitsQ:WhywediscusstheLDU/PDU?1.4LayeredArchitectureandMultimediaWhatarebasicrequirementsformultimediacommunicationnetworks?Howdoesmultimediaassociatewithnetworkarchitecture?Istherealayeredmodelformultimediacommunicationnetworks?1.4LayeredArchitectureandMultimediaReviewofnetworkreferencemodelFunctionsareorganizedintolayers.Servicesoflayernareimplementedbyprotocolentitiesatlayernusingtheservicesoflayern-1.Newservices(oflayern)Basicservices(oflayern-1)ProtocolentityoflayernProtocolentityoflayernNodeANodeB1.4LayeredArchitectureandMultimediaMultimediacommunicationputsseveralrequirementsonservicesandprotocols.Inthissection:Requirementsofmultimediacommunications;Associationwithlayeredarchitecture;OpenDataNetworkmodel.1.4LAM–RequirementsofMMcomm. Followingrequirementsmustbetakenintoaccountformultimediacommunications:Audioandvideoprocessingneedtobeboundedbytime,includingprocessorperformance,datatransferoverbusandstorageforprotocolprocessing.End-to-endjittermustbebounded.Largerjittervaluesmeanlargerbufferandhigherend-to-enddelay;1.4LAM–RequirementsofMMcomm.Multicastforcooperativeworkapplication,suchasvideoconferencing,shouldbesupported;Mechanismsforsynchronizingdifferentdatastreams;Multimediacommunicationmustbecompatiblewiththemostwidelyusedcommunicationprotocolsandmustmakeuseofexistingandfuturenetworks;1.4LAM–RequirementsofMMcomm.Thecommunicationofdiscretedatashouldnotstarvebecauseofpreferredorguaranteedvideo/audiotransmission.Fairnessprincipleamongdifferentapplications,usersandworkstationsmustbeenforced.Servicemustbeabletohandlefluctuationsofthevideo/audiodatarate.1.4LAM–Associationwithlayeredarchitecture

Physicallayertransmissionofindividualbitsoverthephysicalmedium.Foraudio/video,thedelaysmustbeminimizedandarelativelyhighbandwidthshouldbeachieved.DatalinklayerTransmissionofdataframes;errorcheckandcorrection;flowcontrol;blocksynchronization.Continuousstreamrequiresreservationandthroughputguaranteesoveraline.1.4LAM–Associationwithlayeredarchitecture

DatalinklayerToavoidlargerdelays,theerrorcontrolformultimediatransmissionneedsadifferentmechanismthanre-transmission,becausealateframeisnotusefulforreal-timeapplications.Newhigh-speednetworksarebasedonfiberoptics,theremaynotbeaneedforanyerrorcontrolatthislayerbecauseoftheirverylowtransmissionerrorrate.1.4LAM–Associationwithlayeredarchitecture

NetworklayerPacketsovernetworks;addressing;congestioncontrol;internetworking;errorhandling;routing,etc.Continuousstreamsrequireresourcereservationandguaranteesfortransmissionatthislayer.Thereservationmustbedonealongthepathbetweenthecommunicatingstations.

1.4LAM–Associationwithlayeredarchitecture

NetworklayerConnection-orientedbehaviorisneededwherethereservationismadeduringtheconnectionsetup.Throughthisapproach,end-to-enddelaywithsmalljitterandcorrectpacketorderingcanbeenforced.Multicastfunctionisneededinthislayer.QoS:qualityofservices.1.4LAM–Associationwithlayeredarchitecture

TransportlayerEndtoendtransport.QoSissues.SynchronizationbetweenLDUsofoneconnection,andbetweenSDUs(session)ofdifferentconnections(audio/video/text).Real-timetransport.

1.4LAM–Associationwithlayeredarchitecture

ApplicationlayerAllapplication-specificserviceandprotocols.DatacodingAudioandvideoformatsconversion.Multimediasession(point-to-pointsession;multicastsession;multidropsession).Servicesforsupportofrealtimeaccessandtransmission.e.g.VoD,videoconferencing,distancelearning,etc.

1.4LAM–OpenDataNetworkModel

ODN(OpenDataNetwork)modelrecentlyproposedbyapanelofnetworkengineers.ThepurposeoftheODNmodelisnottodevelopastandardlikeOSImodel,buttohelpunderstandhowitmaybepossibletointerconnecttelephone,computer,andCATVnetworks.1.4LAM–OpenDataNetworkModel

SONET,DBS,CATV,WirelesslinksATM,IP,CDPD,FrameRelay,X.25Directory,Security,Compression,RTP,RSVPEmail,WWWaudio-visualapp.applicationsmiddlewarebearerbitways1.4LAM–OpenDataNetworkModel

BitwaysTransmissionofbitstreamsoveralink.E.g.SONET;DBS(DirectBroadcastSatellite);CATV;cellularradiochannel;otherwirelessconnection.Bitwayscanbecharacterizedbyitsspeed,delay,anderrorrate.BearerEnd-to-endtransportofbitstreamsinspecificformats.E.g.ATM;IP;FrameRelay;CDPD(CellularDigitalPacketData);etc.1.4LAM–OpenDataNetworkModel

MiddlewareGenericserviceusedbyapplications.E.g.directories;compression;security;Real-timetransportprotocol;resourcereservation.ApplicationsProtocolsusedbyapplications.Applications:email;WWW;VoD;VideoConferencing.1.5SummaryLecturesorganization:Networksdomain:subnet,bearerServicesdomain:protocol,QoSApplicationdomain:distributedMMappl.Systemdomain:synch.Reqr.12634571.5SummaryFutureinformationsuperhighwaywillcompriseacollectionofheterogeneousnetworks:circuit-switchedSONETnetworks,fiber-coaxialcabledistributionnetworks,wirelessaccess,andInternet.Communicationservicestodayareprovidedbywire,wirelesstelephone,CATV,anddatanetwork.Thesenetworksareconvergingintheirabilitytoprovideintegratedservices.1.5SummaryChallengeistomakeitpossibletointer-operatetheseheterogeneousnetworksinwaysthatareextensibleandsecureandthatprovidethenecessaryrangeofservicequality.Continuousmedia(e.g.Videoandaudio)transmissionisrealchallenge.DiscussionsApplicationsinMilitary,security,intelligenceusingMultimedianetworkingandcommunications?WhatisaSession?Innetworkarchitecture,alltheactivitieswhichtakeplaceduringtheestablishment,maintenanceandreleaseoftheconnection.Theperiodoftimeduringwhichauserofaterminalcancommunicatewithaninteractivesystem,usually,theelapsedtimebetweenlogonandlogoff.Incommunications,theactiveconnectionandtransmissionofdatabetweentwousersatterminals,betweentwocomputersorbetweenauserandacomputer.Chapter2MultimediaNetworks:RequirementsandPerformanceIssuesProf.GuohuiLiSchoolofInformationSystemandManagementNationalUniversityofDefenseTechnologySpring2010COURSE600-081205602Chapter2

2.1Distributedmultimediaapplications2.2Peer-to-Peerandmulti-peercommunications2.3Performanceparameters2.4QualityofService2.5Multimediatransmissionrequirements2.6Summary2.1DistributedmultimediaapplicationsIssuesTomakethediscussionofmultimediatransmissionrequirementsmoreconcrete,westartbydiscussingafewcommonlyusedmultimediaapplications.Howdotheseapplicationsworkandwhatcharacteristicsaretherefortheseapplications.2.1Distributedmultimediaapplications1.AudioandvideostreamsStreamingaudioandvideoapplications(e.g.Realplayer,Winamp,etc.liveradioandbroadcast)enableyoutolistentoorviewprogramasitisbeingtransferred.Duringtheirtravelacrossthenetwork,thepacketssuffervariabledelays.Thedestinationbuffersafewpacketsbeforeitstartsplayingthembackasanaudioorvideostream.Thebufferingabsorbsthedelayfluctuations.2.1Distributedmultimediaapplications2.VideoconferencingForconversations,theonewaydelayisbarelynoticeableifitislessthan100ms.Beyond350ms,thedelaymakestheconversationunpleasant.Smalldelayrequirementofvoiceimpliesthatvoicesamplesmustbeplacedinsmallpackets.Packetizationwillintroducesomeofdelaysthataddtooverallend-to-enddelay.2.1Distributedmultimediaapplications3.WorldWideWeb-WWWWWWisadistributedapplicationthatenablesyoutonavigatethroughasetofhyperlinkeddocuments,calledWebpages.EachWebpagemaycontaintext,pictures,audioclips,videoclips,andpossiblylinks.WhenyoubrowsetheWeb,youinitiateasequenceoffiletransfersaccordingtoHTTP.Actually,audio/videostream,videoconferencing,videoondemandcanbeInternetapplications.2.2Peer-to-PeerandmultipeercommunicationsThreebasicmodesUnicast:therearetwocommunicatingpartners,orpeers,andalsocalledpeer-to-peermode.Multicast:involves1toncommunications,orpeer-to-multipeer.e.g.onespeaker,manyparticipantsinvideoconferencinganddistancelearning.Broadcast:1toalldestinationsovernetwork.e.g.LAN,wirelessnetwork.2.3PerformanceparametersHowtodecidewhetheranetworkwillbeabletocarrymultimediatrafficornot?2.3PerformanceparametersSolution:1.Asetofparametersareusedtostateclearlywhattheapplicationneedsfromnetwork.2.Asimilarsetofparametersareusedtospecifywhatthenetworkcanprovide.2.3PerformanceparametersSASfactors-SynchronizationaccuracyspecificationDelay;Delayjitter;Delayskew;Errorrate.TrafficsynchronizationparametersThroughput;Burstiness.NPP-NetworkperformanceparametersNetworkthroughput;Networkingdelay;Delayvariance;Errorrate.2.3.1SASfactorsReview:(multimediasystem)Asynchronoussystem

thereisnowell-definedtimingrelationshipbetweentheobjectsofoneormorestream(s).inter-stream:betweenstreams.intra-stream:withinastream.2.3.1SASfactorsSynchronousandisochronoussystemswell-definedtemporalrelationshipsexistbetweenobjects.isochronous:equaltime;itisapplicablewhenonestreamisconsideredatatime.(intramedia)synchronous:sametime;itisapplicablemainlytothetemporalrelationshipbetweentwodifferentmediastreams.(intermedia)2.3.1SASfactorsisochronousstream:hasequaltimegapsbetweenconsecutiveobjects.synchronousstream:interstreamsynchronyimpliesthattimegapsbetweenrelatedobjectsareequaltoaconstantT.Mostlyoften,T=0.IsochronousstreamsynchronousstreamsTaudiovideoaudio2.3.1SASfactors1.DelayfactorDelayfactorisusedtomeasuretheend-to-endtimedelay,whichmeansthetimeittakestotransmitablockofdatafromthesendingtoreceivingend.Itcomprises:Propagationdelay:aphysicalparameterdenotingthepropagationtimerequiredtosendabitfromonesitetoanother.Itisdependentonlyuponthedistancetraversed.(e.g.satellitelink)Transmissiondelay:thetimerequiredtotransmitablockofdataovernetwork.Itisdependentuponthebitrateofthenetworkandprocessingdelaysintheintermediatenodes(routingandbuffering).2.3.1SASfactorsNetworkdelay:composedofthepropagationdelayandtransmissiondelay.Interfacedelay:thedelayincurredbetweenthetimethatasenderis

readytobeginsendingablockofdataandtimethatthenetworkisreadytotransmitthedata.Forthemultimedia,italsoshouldincludetheencodingtimeinthesendingend,bufferinganddecodingtimeinthereceivingend.End-to-enddelaytransmissiondelayinterfacedelayinterfacedelaypropagationdelaynetworkdelay2.3.1SASfactors2.DelayjitterDuetovariationindelayfactors,thetemporalrelationshipscandeviatefromtheirdesiredvalues.Thisvariationisdescribedbyafactorcalledjitter.Jitteristheinstantaneousdifferencebetweenthedesiredpresentationstimesandtheactualpresentationtimesofdatastreams.2.3.1SASfactorsIntramediajitter:occurringinasingledatastream.Thedeviationsinthepresentationtimeareinstantaneous,notcumulative.Theconsequenceinvideoclip:shakypicture;inaudio:quiveringvoice.Intermediajitter:theinstantaneousdeviationsinthepresentationtimesoftherelatedpacketsinthetwostreamsleadstointermediajitter.Theconsequenceinvideo/audio:lossoflipsyn.2.3.1SASfactorsDesiredtimeactualtimeIntramediajittervideotimeaudiotimeIntermediajitter2.3.1SASfactors3.DelayskewSkewistheaveragedifferencebetweenthedesiredpresentationtimesandtheactualpresentationtimesofdatastreams.Inaskewedpresentation,theaveragerateofobjectdeliverydeviatesfromthedesiredaveragerate.2.3.1SASfactorsIntramediaskew:continuousasynchronyinisochronousdatastream.Theconsequence:eithersloworfastmovingpictureinvideo;lowerorhigherpitchthanthenormalinaudio.Intermediaskew:theaveragedeviationinthepresentationtimesoftherelatedobjectsinthetwostreams.Theconsequence:completelossoflip-syn.inaudio/video.2.3.1SASfactors

Qestion:Couldyoudrawthefiguresofshowinghowintramediaskewandintermediaskewoccurindatastream(s)?

2.3.1SASfactors4.ErrorrateAcceptableleveloferrordiffersfromonemediatypetoanother.Executablecodetextimageaudiovideo2.3.1SASfactorsBER-BitErrorRateRatioofthenumberofbiterrorsdetectedto