ITU-T H.248.20 (11 2002) (英) Gateway control proto

INTERNATIONALTELECOMMUNICATIONUNIONITU-TH.248.20TELECOMMUNICATIONSTANDARDIZATIONSECTOROFITU(11/2002)SERIESH:AUDIOVISUALANDMULTIMEDIASYSTEMSInfrastructureofaudiovisualservices–CommunicationproceduresGatewaycontrolprotocol:TheuseoflocalandremotedescriptorswithH.221andH.223multiplexingITU-TRecommendationH.248.20ITU-TH-SERIESRECOMMENDATIONSAUDIOVISUALANDMULTIMEDIASYSTEMSCHARACTERISTICSOFVISUALTELEPHONESYSTEMSH.100–H.199INFRASTRUCTUREOFAUDIOVISUALSERVICESGeneralH.200–H.219TransmissionmultiplexingandsynchronizationH.220–H.229SystemsaspectsH.230–H.239CommunicationproceduresH.240–H.259CodingofmovingvideoH.260–H.279RelatedsystemsaspectsH.280–H.299SYSTEMSANDTERMINALEQUIPMENTFORAUDIOVISUALSERVICESH.300–H.399SUPPLEMENTARYSERVICESFORMULTIMEDIAH.450–H.499MOBILITYANDCOLLABORATIONPROCEDURESOverviewofMobilityandCollaboration,definitions,protocolsandproceduresH.500–H.509MobilityforH-SeriesmultimediasystemsandservicesH.510–H.519MobilemultimediacollaborationapplicationsandservicesH.520–H.529SecurityformobilemultimediasystemsandservicesH.530–H.539SecurityformobilemultimediacollaborationapplicationsandservicesH.540–H.549MobilityinterworkingproceduresH.550–H.559Mobilemultimediacollaborationinter-workingproceduresH.560–H.569Forfurtherdetails,pleaserefertothelistofITU-TRecommendations.ITU-TRec.H.248.20(11/2002)iITU-TRecommendationH.248.20Gatewaycontrolprotocol:TheuseoflocalandremotedescriptorswithH.221andH.223multiplexingSummaryThisRecommendationdefineshowtheLocalandRemotedescriptorsareusedwithinH.248,H.221andH.223multiplexing(MUX)terminationstoassociatedemultiplexedstreams(logicalchannels)withH.248.1streams.SourceITU-TRecommendationH.248.20waspreparedbyITU-TStudyGroup16(2001-2004)andapprovedundertheWTSAResolution1procedureon29November2002.iiITU-TRec.H.248.20(11/2002)FOREWORDTheInternationalTelecommunicationUnion(ITU)istheUnitedNationsspecializedagencyinthefieldoftelecommunications.TheITUTelecommunicationStandardizationSector(ITU-T)isapermanentorganofITU.ITU-Tisresponsibleforstudyingtechnical,operatingandtariffquestionsandissuingRecommendationsonthemwithaviewtostandardizingtelecommunicationsonaworldwidebasis.TheWorldTelecommunicationStandardizationAssembly(WTSA),whichmeetseveryfouryears,establishesthetopicsforstudybytheITU-Tstudygroupswhich,inturn,produceRecommendationsonthesetopics.TheapprovalofITU-TRecommendationsiscoveredbytheprocedurelaiddowninWTSAResolution1.InsomeareasofinformationtechnologywhichfallwithinITU-T'spurview,thenecessarystandardsarepreparedonacollaborativebasiswithISOandIEC.NOTEInthisRecommendation,theexpressionAdministrationisusedforconcisenesstoindicatebothatelecommunicationadministrationandarecognizedoperatingagency.INTELLECTUALPROPERTYRIGHTSITUdrawsattentiontothepossibilitythatthepracticeorimplementationofthisRecommendationmayinvolvetheuseofaclaimedIntellectualPropertyRight.ITUtakesnopositionconcerningtheevidence,validityorapplicabilityofclaimedIntellectualPropertyRights,whetherassertedbyITUmembersorothersoutsideoftheRecommendationdevelopmentprocess.AsofthedateofapprovalofthisRecommendation,ITUhadnotreceivednoticeofintellectualproperty,protectedbypatents,whichmayberequiredtoimplementthisRecommendation.However,implementorsarecautionedthatthismaynotrepresentthelatestinformationandarethereforestronglyurgedtoconsulttheTSBpatentdatabase.ITU2003Allrightsreserved.Nopartofthispublicationmaybereproduced,byanymeanswhatsoever,withoutthepriorwrittenpermissionofITU.ITU-TRec.H.248.20(11/2002)iiiCONTENTSPage1Scope............................................................................................................................12References.....................................................................................................................13Definitions....................................................................................................................24Abbreviations................................................................................................................25LogicalchannelparameterswithintheMUXtermination...........................................25.1Textencoding.................................................................................................25.1.1c=lineLineforH.221andH.223MUXtermination..................................25.1.2m=lineLineforH.221andH.223MUXtermination.................................35.2Binaryencoding..............................................................................................36Example........................................................................................................................36.1Contextmodel................................................................................................46.2ThemediadescriptorfortheTDMtermination.............................................46.3ThemultiplexdescriptorfortheMUXtermination.......................................46.4ThemediadescriptorfortheMUXtermination.............................................46.5ThemediadescriptorfortheRTPtermination.............