ITU-T G.722.1 (05 2005) (英) Low-complexity coding…

InternationalTelecommunicationUnionITU-TG.722.1TELECOMMUNICATIONSTANDARDIZATIONSECTOROFITU(05/2005)SERIESG:TRANSMISSIONSYSTEMSANDMEDIA,DIGITALSYSTEMSANDNETWORKSDigitalterminalequipments–CodingofanaloguesignalsbymethodsotherthanPCMLow-complexitycodingat24and32kbit/sforhands-freeoperationinsystemswithlowframelossITU-TRecommendationG.722.1ITU-TG-SERIESRECOMMENDATIONSTRANSMISSIONSYSTEMSANDMEDIA,DIGITALSYSTEMSANDNETWORKSINTERNATIONALTELEPHONECONNECTIONSANDCIRCUITSG.100–G.199GENERALCHARACTERISTICSCOMMONTOALLANALOGUECARRIER-TRANSMISSIONSYSTEMSG.200–G.299INDIVIDUALCHARACTERISTICSOFINTERNATIONALCARRIERTELEPHONESYSTEMSONMETALLICLINESG.300–G.399GENERALCHARACTERISTICSOFINTERNATIONALCARRIERTELEPHONESYSTEMSONRADIO-RELAYORSATELLITELINKSANDINTERCONNECTIONWITHMETALLICLINESG.400–G.449COORDINATIONOFRADIOTELEPHONYANDLINETELEPHONYG.450–G.499TRANSMISSIONMEDIACHARACTERISTICSG.600–G.699DIGITALTERMINALEQUIPMENTSG.700–G.799GeneralG.700–G.709CodingofanaloguesignalsbypulsecodemodulationG.710–G.719CodingofanaloguesignalsbymethodsotherthanPCMG.720–G.729PrincipalcharacteristicsofprimarymultiplexequipmentG.730–G.739PrincipalcharacteristicsofsecondordermultiplexequipmentG.740–G.749PrincipalcharacteristicsofhigherordermultiplexequipmentG.750–G.759PrincipalcharacteristicsoftranscoderanddigitalmultiplicationequipmentG.760–G.769Operations,administrationandmaintenancefeaturesoftransmissionequipmentG.770–G.779PrincipalcharacteristicsofmultiplexingequipmentforthesynchronousdigitalhierarchyG.780–G.789OtherterminalequipmentG.790–G.799DIGITALNETWORKSG.800–G.899DIGITALSECTIONSANDDIGITALLINESYSTEMG.900–G.999QUALITYOFSERVICEANDPERFORMANCE–GENERICANDUSER-RELATEDASPECTSG.1000–G.1999TRANSMISSIONMEDIACHARACTERISTICSG.6000–G.6999DATAOVERTRANSPORT–GENERICASPECTSG.7000–G.7999ETHERNETOVERTRANSPORTASPECTSG.8000–G.8999ACCESSNETWORKSG.9000–G.9999Forfurtherdetails,pleaserefertothelistofITU-TRecommendations.ITU-TRec.G.722.1(05/2005)iITU-TRecommendationG.722.1Lowcomplexitycodingat24and32kbit/sforhands-freeoperationinsystemswithlowframelossSummaryThisRecommendationdescribesalowcomplexityencoderanddecoderthatmaybeusedfor7-kHzbandwidthaudiosignalsworkingat24kbit/sor32kbit/s.Further,thisalgorithmisrecommendedforuseinhands-freeapplicationssuchasconferencingwherethereisalowprobabilityofframeloss.Itmaybeusedwithspeechormusicinputs.Thebitratemaybechangedatany20-msframeboundary.NewAnnexCcontainsthedescriptionofalow-complexityextensionmodetoG.722.1,whichdoublesthealgorithmtopermit14-kHzaudiobandwidthusinga32-kHzaudiosamplerate,at24,32,and48kbit/s.Thismodeissuitableforuseinvideoconferencing,teleconferencing,andInternetstreamingapplications,andusesthesame20-msframelength,40-msalgorithmicdelay,andsamealgorithmicstepsasthe7-kHzmode.Lessthan5.5WMOPSarerequiredforencodinganddecodinginthebaseline7-kHzmode,andlessthan11WMOPSarerequiredforencodinganddecodinginthe14-kHzmodeofAnnexC.ThisRecommendationincludesasoftwarepackagewhichcontainstheencoderanddecodersourcecodeandasetoftestvectorsfordevelopers.Thesevectorsareatoolprovidinganindicationofsuccessinimplementingthiscode.Thefixed-pointcodeimplementsboththe7-kHzmode(mainbody)andthe14-kHzmode(AnnexC).Thefloatingpointimplementsonlythe7-kHzmode.ThiseditionincludesCorrigendum1(2008-06)thatcorrectstheCsourcecodeforfiledecoder.cinAnnexB.NochangesaremadetothetextoftheRecommendation.TheCsourcecodeforthisintegratededitionislabelledasRelease2.1forconsistency.SourceITU-TRecommendationG.722.1wasapprovedon14May2005byITU-TStudyGroup16(2005-2008)undertheITU-TRecommendationA.8procedure.Corrigendum1wasalsoapprovedon13June2008byITU-TStudyGroup16(2005-2008)undertheITU-TRecommendationA.8procedure.iiITU-TRec.G.722.1(05/2005)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.CompliancewiththisRecommendationisvoluntary.However,theRecommendationmaycontaincertainmandatoryprovisions(toensuree.g.interoperabilityorapplicability)andcompliancewiththeRecommendationisachievedwhenallofthesemandatoryprovisionsaremet.Thewordsshallorsomeotherobligatorylanguagesuchasmustandthenegativeequivalentsareusedtoexpressrequirements.TheuseofsuchwordsdoesnotsuggestthatcompliancewiththeRecommendationisrequiredofanyparty.INTELLECTUALPROPERTYRIGHTSITUdrawsattentiontot