外文翻译原文-一种基于RTCP服务模式上可扩展的智能视频监控系统

AScalableIntelligentServiceModelforVideoSurveillanceSystemBasedonRTCPYimamuaishan.Abudoulikemu1YuanmingHuang2ChangqingYe31.InformationandConstructionCollegeofUrumqiVocationalUniversity.2.SchoolofComputer,GuangXiEconomicManagementCadreCollege,GuangXi,Nanning530007.3.Schoolofeducationtechnology,EastChinaNormalUniversity.Shanghai.Email:AbstractAsanextensiblesignalingprotocol,RTCPprotocolcanbeappliedindevelopingvideosurveillancesystem.Traditionally,forRTP-basedcentralizedvideosurveillancesystem,surveillancescaleislimitedbyboththecapabilityofsurveillanceserverandtheavailabilityofbandwidth.Thispaperfocusesonhowtokeepsurveillancecapabilitywhenthenumberofvideosurveillancesystemincreases.BasedonthestudyoftheRTCPProtocol,weanalyzethedrawbackoftheexistingvideosurveillancesystemmodel,andproposethescalableservicemodelforvideosurveillancesystem.Bythismodel,theextraservicerequestscanbetransferredandservedinthecooperatedvideoservers.Thepaperpresentsthevideosurveillancecontrolpolicyofthemodelindetail.Wedevelopedaprototypeofvideosurveillancesystembasedonabovemodel.ExperimentalresultshowtheservicemodelworkswellKeywords-RTCP;VideoSurveillanceSystem;CapabilityScalabilty;ServiceModelI.INTRODUCTIONThefastdevelopmentofInternettechnologieshasprovidedthebasisformultimediavideosurveillancesysteminIPnetwork1.Withthefunctionoftransmittingmultimediainformation,suchastext,graphics,audioandvideo,Videosurveillancesystembreaksthelimitofhumancommunicationduetothegeographicallocationofparticipants.Atpresent,therearetwostandardstosupportthedevelopmentofvideoconferencesystems,i.e.ITU-TH.323andtheRTCPrecommendedbytheIETF2.BecauseH.323followsthetraditionaltelephonysignalmodel,itisdifficulttocontrolandbeextended.However,RTCPisflexibleandopen.Thus,inthispaper,RTCPisadoptedasthebasistostudythedynamicscalablevideoconferencingsystem.Thereisthemodelforvideosurveillancesystem:looselycoupledconference,fullydistributedmultipartyvideosurveillanceandtightlycoupledconference3.Theircommondrawbackisabsenceofdynamicextension,i.e.theyarenotabletodynamicallyincreasethecapacityofvideosurveillancesystemduringthemonitoring.Toovercometheshortcoming,thispaperproposesadynamicscalableservicemodelforvideosurveillancesystembasedonRTCP.Underthepreconditionofnonegativeeffectsonthevideosurveillancesystemtherequirementsonextendingthesystemscapabilitycanbemetbydynamicincreasingofsurveillanceserversandbytransferringthesubsequentservicestothecooperatedsurveillanceservers45.Comparedwiththetraditionalcrisesordisasters,humanbeinglackin-depthscientificunderstandingforevolutionlawofthoseunconventionalemergencies,andinpracticethereisalsoalackofquantitativeassessmentmethodstothewholesystemcapabilitytocopewiththerisks.Thepracticeofemergencyresponseforsocialunconventionaleventsshowsthatitsparticularlyimportanthowtocontroltheemergencyresponseplanattheearliesttimeaccordingtothenatureofeventsandextentofdamage,andhowtoallocateemergencymeasureswithcorrespondingemergencyresponsecapability.Ifrapid,rational,timelyandeffectiveemergencyresponsemeasurescouldbetakeninaccordancewiththeevolutionlawofsocialunconventionalemergencies,theincidentcontroltimeandpossibledamagesandlosseswouldbesubstantiallyreduced.Inordertorealizetheabovegoals,itsimperativetostudytherevolutionlawandresponsecapabilityofsocialunconventionalemergencies.Therestofthepaperisorganizedasfollows:Insection2,wediscusstherelatedwork.Section3presentsascalableservicemodelforvideosurveillancesystembasedonRTCP.Insection4,wedescribetheevolutionmodelofemergencyevent.Insection5,weintroducetheimplementationofvideosurveillancesystembasedontheRTCP.Finally,wemakesomeconclusionsinsection6.II.RELATEDWORKA.RTCPProtocolRTCP6wasdevelopedbytheIETFmultipartymultimediasessioncontrolworkinggroupandhasbeenappliedbroadly.RTCPisanapplicationlayercontrolprotocolthatcanestablish,modifyandterminatemultimediasessionssuchasInternetconferencing,telephony,eventsnotificationandinstantmessaging.RTCPissimilarinsyntaxandgrammartogetherInternetprotocolssuchasSMTP(SimpleMailTransferProtocol)usedfore-mailandHTTPusedfortheWorldWideWeb.ThearchitectureofRTCPfollowstheclient-servermodel,theunderlyingtransportofRTCPmessagescaneitherbeinUDP,TCPorStreamControltransmissionProtocol(SCTP)7.However,RTCPisnotaverticallyintegratedcommunicationssystem,andacompletemultimediaarchitecturecannotbebuiltonlybyusingRTCP.Usually,RTCPisratheracomponentthatcanbeusedwithotherIETFprotocolstobuildacompletemultimediaarchitecture.Typically,thesearchitecturesincludeprotocolssuchasthe20102ndInternationalConferenceonSignalProcessingSystems(ICSPS)V3-346978-1-4244-6893-5/$26.002010IEEECReal-timeTransportProtocol(RTP)8fortransportingreal-timedataandprovidingQoSfeedback,theReal-TimeStreamingProtocol(RTSP)forcontrollingdeliveryofstreamingmedia,andtheSessionDescriptionProtocol(SDP)whichisusedtodescribemultimediasessions.TherearesixrequestmethodsmainlydefinedinRTCP9:INVITE,ACK,BYE,OPTION,CANCELandREGISTER.Certainly,RTCPhasalsobeenextendedtogenerateeventnotificationsandinstantmessages10.B.VideoSurveillanceSystemBasedonRTCPEffortstoimplementRTCPfeaturesforvideoconferencesystemhavebeengoingonforthepastfewyears11.Typically,therearethreemodelsforconferencingcontrol:looselycoupledconference,fullydistributedmultipartyconferenceandtightlycoupledconference12.DuetotheabsenceofawidelyavailablemulticastserviceonInternetatpresent,themodelofourimplementationisbasedonthecurrentlymorecommoncentralizedframeworkandtightlycontrolledsessionmodel.IETFdescribesaframeworkinsomedraftsforhowsuchRTCP-basedtightlycoupledconferencescanbeheld,includingtheoverallarchitecture,protocolcomponentsneededformulti-partyconferencingandtheflowsoftheconference.TheIETFframeworkprovidesuswiththeresearchbasis.However,IETFframeworkhasadrawbackthereisonlyoneconferenceserveractingascentralcontrolunit,whoseconferenceservicecapabilitylimitsthescaleofconference,sothattheconferencelacksofextensibility13.Weovercometheshortcomingbydynamicallyincreasingthenumberofconferenceserversandtransferringthesubsequentservicetotheincreasedconferenceserverwithoutstoppingtheconference.Weadopttheobjectorientedmethodtomanageconferences,whichmeanstherealizationofconferencedynamicextensiondependsontheaccessionofthemembersunderthecasethateachconferenceserverjoiningtheconferencebecomesonememberoftheconferenceobjects.WealsodefinesomespecialconferencepoliciesthatembodytheaboveideaandthesepoliciescanbeimplementedbyRTCP14.III.EVOLUTIONMODELOFSOCIALUNCONVENTIONALEMERGENCYThescalableservicemodelforRTCP-basedvideoInordertostudytheevolutionlawofsocialunconventionalemergency,weneedanobjectiveandscientificcharacterizationanddescriptionofthewholeevolutionprocessofsocialunconventionalemergencyovertime15.Thus,weintroducetheconcept“concerndegreeofsocialunconventionalemergency”.Sincethemostdirectmanifestationofincidentsfromoccurrencetodisappearanceisaseriesofphenomenaovertime,thereexistsinevitablelinkbetweenincidentsandphenomena.Foranything,wecanfindsomerepresentedphenomenaasdescription.Concerndegreecanbeunderstoodasthosephenomenathatbestreflecttheincidentevolution.SurveillancesystemconsistsofthreekindsofRTCPentities16.Characteristicsofconcerndegreeisusedtodescribeconcerndegree,andcandescribeconcerndegreefrommanyaspectsinaccordancewithactualsituation,suchasoccurrenceprobabilityofconcerndegree,lossdegreeandpanicdegreeresultingfromconcerndegree,etc.Supposethesocialunconventionalemergencyrecordedasx,ande,p,trespectivelyexpressconcerndegreeofsocialunconventionalemergency,characteristicsofconcerndegree,andtimeattributes,thusthemathematicalexpressionfortheevolutionmodelis:x=f(e,p,t),wherefexpressesthemappingofconcerndegreeofsocialunconventionalemergency,characteristicsofconcerndegreeandtimeattributestosocialunconventionalemergency.Bystudyingthismodel,wecanhavescientificunderstandingofevolutionlawofsocialunconventionalemergency.A.SurveillanceObjectAsalogicentity,aconferenceobject,createdandmanagedbyMS,createsandmanagesthesurveillancemembersofthevideo.Therelationshipbetweenconferenceandconferenceobjectisone-to-one.Therearetwotablesinthevideosurveillanceobject:UserAgentTablePAT)andConferenceServer.ThetwotableslisttherelatedinformationofUAsandCSsinthevideosurveillancesystem,respectively.Thevirtuallinelinkingthetwotablesmeansthatoneuserhasloggedintosomeconferenceserver.Forexample,thevirtuallinelinkingUA1toCSlindicatestheUAIhasloggedintotheCSI.Furthermore,wenotethattheResourceRequestModule(RRM),asapartofthesurveillanceobject,isdevotedtocheckingtheloadstatusofeveryCSexistingintheCSTandrequestingnewCStojointhevideosurveillancesystem.B.MonitorServerInthemodel,wedesignasingleMSwhichcollectivelyimplementsthefunctionsofregisterserver,redirectserverandproxyserver.Inaddition,theadditionalfunctionsofMSareasfollows:(1)creatingandmanagingtheconferenceobject,(2)resourcemanagementandscheduling.TheMSiscomposedoffivemodules:CommunicationInterface(CI),ConferenceObjectQueue(COQ),ResourceScheduler(RS),UserAgentManagementTable(UAMT)andConferenceServerManagementTable(CSMT).CItakeschargeoftheMScommunicationwithCSsandUAs.Creating,managinganddeletingtheconferenceobjectaretheresponsibilitiestakenbyCOQ.RSservicesresourcemanagementandscheduling.TheUAMTandCSMTmanagetheinformationofalltheregisteredCSsandUAs,C.SurveillanceControlPoliciesAtfirst,weintroducetheconceptionofloadratio.TheloadratioistheperformanceindexofCS.Inthepaper,wetaketheresourceutilizationsofCSastheloadratioofCSbecauseitshowsanapproximatelylinearpositivecorrelationbetweentheresourceutilizationandtheloadratio.Inordertoimplementthedynamicscalability,wemakesomesurveillancecontrolpoliciesforthemodel.20102ndInternationalConferenceonSignalProcessingSystems(ICSPS)V3-347xOncetheUAorCSlogsintothenetwork,itregistersintotheMS.TrmationofUAsandCSsarestoredintotheUAMTandCSMTrespectively.AsaCSregisteringintotheMSsuccessfully,theMSaskstheCStoreportitsloadratioeveryacertaintime(e.g.5s).TheloadratioiswrittenintotheCSMTandisalsostoredintotheCSTofaconferenceiftheCShasjoinedtheconference.xBeforeaconferenceholding,asurveillanceobjectwillbecreatedandinsertedintoCOQbyMS,andtheRRMofthesurveillanceobjectwillrequesttheRStoselectaCSastheinitialCSofthevideo.Then,thesurveillanceobjectwillcopytherelativeitem&comtheCSMTtoitsCST.Atthesametime,theMSinvitestheCStojointhevideosurveillancesystem.xUAwillsendarequesttoMSfortheCSaddress,ifitexpectstojoinavideosurveillancesystem.AftertheMSreceivestherequest,theUAToftheconferenceobjectwillcopytherelativeitemfromtheUAMT.Then,theRRMchoosestheCSwiththeleastloadamongallCSsofthevideosurveillancetointeractthevideosignalswiththeUA.Finally,thesurveillanceobjectwillbuilduptherelationshipbetweentheUAandCS.OnceaUAexitsaconferenceorfailstologintoCS,thesurveillanceobjectwillcanceltherelationshipbetweentheUAandCSanddeletetherelateditemsoftheUAfromtheUATxDuringaconference,theRRMofthesurveillanceobjectwillchecktheloadstatusofeveryCSinCST.OncetheloadofeachCSoftheconferencereachestheutmost,theRRMwillsendarequestforanewCStotheRS.ThentheRSwillselectCSwiththeleastloadamongthosewhohaventjoinedthevideosurveillancesystemfromtheCSMT,andthentheselectedCSwillbeinsertedintotheCST.Atthesametime,theMSsendsarequesttoinvitetheCStojointhevideosurveillancesystem.Whenthisstepisaccomplished,theservicerequestsofthesubsequentUAswillbetransferredtotheCSaccordingtotheabove.xWhenasurveillanceisover,theMSwillsendamessagetoCSanddeletethesurveillanceobjectcorrespondingtothemonitoringfromtheCOQIV.THERTCPFLOWSOFTHEMODELInthissection,wewilllookattheRTCPflowsofsomeinterestingphasesintheconference,wheretheRTCPflowsconformtotheconferencecontrolpoliciesofthemodel.A.TheUAFlowsWhenauser(UA)usinganyterminallogsontoanetwork,theREGISTERmessagesaresenttotheMS.Thesemessagesrecordtherelatedinformation,suchasaddressandURI,arestoredintotheUAMT.TheflowofUAjoiningthevideosurveillancesystemisasfollow.First,afterreceivingtheINVITErequestsentbyWAforgettingtheaddressofCS,MSresponsestheADDRESSmessagewhichincludestheinformationabouttheaddressofCS,andthenUAreturnsACKtoMS.Second,UAjoinstheconference.Finally,theUAsendsMSsuchmultipleSUBSCRIBErequestsastoasktodownloadtheparticipantsinformationoftheconference,ortoasktogettheaudiostreamsorvideostreamsofsomeusers.TheSUBSCRTBErequestcontainsan“event”headerindicatingthetypeofeventtheUAissubscribingtoandan“expires”headerspecifyingthedurationofthesubscription.Therequestcanberefreshedwheneverthesubscriptionhasexpired.Ifasubscriberwantstounsubscribe,itcansendaSUBSCRTBEmessagewithanexpirationtimeofzero.TheSUBSCRIBE(eventdownload)requestaskingtodownloadtheparticipantlistoftheconferencewillbesenttotheMSassoonasaUAjoinstheconference.Afterreceivingthisrequest,MSwillintermittently(e.g.5s)sendtheNOTIFYresponsetotheUAinordertoinformittheparticipantlist.Atthesametime,thisresponsecanalsobetriggeredwhenotherUAsenterorexit.Afterjoiningaconference,theUAwil1sendmediastreamstotheCSonwhichithaslogged.Then,theUAwillreceivemediastreamsfromtheloggedCSorotherCSsifitrequeststhemediastreamsofotherUAswhichhaveloggedontheotherCSs.Furthermore,thereareotherRTCPflowsofUAsuchasaUAinvitinganotherUAtojointheconference.Forexample,ifUA1,asaconferenceuser,expectstoinviteUAZtojointheconference,itwillsendREFERtoMSwhichwillselecttheleastloadCSiamongallCSsoftheconference.TheMSwillsubsequentlysendMESSAGEtoCSiwhichwillsendINVITEsignaltoWA2,inordertoinviteUA2toentrytheconference.WhenaUAexitstheconference,itwillsendBYEmessagetoMSandCS.B.TheCSFlowsTheCSwillsendREGISTERmessagetoMSassoonasitlogsonthenetwork.AfterreceivingthefirstREGISTERfromCS,MSwillsendSUBSCRIBE(event=query)forcheckingtheCSloadratio.Atthesametime,CSintermittently(e.g.5s)respondsNOTIFYmessagetoMSreportingitsloadsituation.Thisstepfollowstheconferencecontrolpolicy.TheRTCPflowofCSdynamicallyjoiningaconferenceisasfollows.Accordingtotheconferencecontrolpolicy(d),wheneachconferenceCShasoverloaded,theMSwillsendMVITEmessagetotheleastloadCSfromtheCSMT.ThentheselectedCSwillrespond200OKtotheMS,ifitagreesonjoiningtheconference.Whentheconferenceisover,theMSwillsendBYEmessagetotheCSwhichresponses200OKtotheMS.Afterhavingreceivedtheresponse,theMSwilldeletetheconferenceobjectaccordingtotheconferencecontrolpolicy.20102ndInternationalConferenceonSignalProcessingSystems(ICSPS)V3-348V.THEPROTOTYPESYSTEMANDPERFORMANCEEVALUATIONThesecurityprecautionsystempresentedherereferstotheconceptofoverallsecurityprecaution,whichincludesallelementsofemergencypreparationsystemandsecurityprecautionsystemaswell.Responsecapabilitycanbeclassifiedasstaticanddynamicresponsecapability.TheformerreferstotheassessmentofresponsecapabilitiesofsecurityprecautionsystemwiththehelpofourevolutionlawmodelwhenincidentXdoesnotoccur,andthelatterreferstotheassessmentofresponsecapabilitiesofsecurityprecautionsystemwiththehelpofreal-timedatathroughdynamicaccessovertime.Staticresponsecapabilityofsecurityprecautionsystemisourfocus.WeshowtheloadratiosofCS1andCS2aseachuserjoinsthevideosurveillancesystem.AsthenumberofUAsincreasesfrom0to37theloadratioofCS1increasesfrom0to86.5%approximatelylinearly,whilethatofCS2stillkeeps0.However,iftheloadratioofCS1isover43.7%,andthesubsequentUAskeeponloggingintoCSI,theresourceofCS1wouldbeexhaustedandtheconferencewouldendabnormally.Toavoidtheemergentsituation,theMSresponsivelysendsINVITErequesttoCS2andinvitesittojointheconferenceactingasthereceiverforthesequentservicerequests.AsthenumberofUasincreasesfrom29to48,theloadratioofCS1keepsunder83.6%,whilethatofCS2increasesfrom0to54%.TheaboveresultsshowthatOUTservicemodelischaracterizedwiththedynamicscalabilitywithoutanynegativeeffectsontheconference.VI.CONCLUSIONThispaperprovidesaservicemodeltosupportdynamicscalabilityofRTCP-basedvideosurveillancesystem.BasedonthestudyoftheRTCPProtocol,weanalyzedthedrawbackoftheexistingvideosurveillancesystemmodels,andproposedadynamicscalableservicemodelforvideosurveillancesystembasedonRTCP.Wealsopresentedthestructure,thesurveillancecontrolpoliciesandRTCPsignalflowsofthemodel.Bythismodel,theextraservicerequestscanbetransferredandservedinthecooperatedvideosurveillanceservers.Furthermore,weimplementedaprototypesystembasedonthemodel,andtheexperimentalresultsshowtheservicemodelworkswell.REFERENCES1ZhuXiao-ning,Du,Wen.StudyontheModeofSocialEmergencyEarlyWarningManagementBasedonGrid.InternationalConferenceonManagementScienceandEngineering2007.pp:2463-24682MouZhenhua,LiMeiling,LiuYongjunStudyonEmergencyTrafficOrganizationofUrb