视讯串流的有效重传及安全机制

1 視訊串流的有效重傳及安全機制 王家輝銘傳大學資訊工程學系 2 PARTI 視訊串流的有效重傳機制Rate sensitiveARQforReal timeVideoStreaming 3 Outline IntroductionMotivationProposedErrorControlSchemeExperimentsandPerformanceConclusionsandFutureWork 4 Introduction MultimediaStreamingServicesCharacteristicsofStreamingServicesErrorResilienceinStreamingServices 5 MultimediaStreamingServices TransportationSchemeinStreamingService NetworkCloud Mediadatasender sendingrate arrivalrate player decoder playbackrate playbackbuffer NetworkCloud MediaServer 6 MultimediaStreamingServices VideoondemandDistancelearningDigitallibraryHomeshoppingVideoconference 7 CharacteristicsofStreamingServices SymmetricVideoConferencing playbackdelay100 200msAsymmetricVideoOnDemand playbackdelay500ms 1secondRequireend to endplaybackqualityRate basedflowcontrolCompressedTosavestorageandnetworkbandwidth VulnerabletoLossVLC VariableLengthCoding Erroraffectsmediaplaybackquality Blastofsound flickeranderrorpropagationinvideo 8 ErrorPropagation BecauseofVLCAsinglebiterrorwilldiscardalargeportionofdata Asinglepacketlossmayaffectthecurrentorthefollowingvideoframes iftheaffectedframesarereferenceframe BecauseofappliedmotioncompensationErrorwillpropagatetothefollowingframes Thisdistortioninthesecondpictureisduetopacketlosses Errorpropagatestotherestofframeswhicharecorrectlyreceived InjonRheeandSrihnathR Joshi IEEEJSAC2000 9 ErrorResilienceinMultimediaStreaming TransportLayerErrorControlFEC ForwardErrorCorrection ARQHybridARQReferencesSurveyinG Carl et al IEEENetwork 1997LuigiRizzo ACMCommunicationReview 1997Wai TianTanandAvidehZakhor PacketVideo1999 10 ErrorResilienceinMultimediaStreaming MediaLayerErrorRecoveryMulti layerencodingMcCanne S et al ACMSigComm Aug 1996MultipledescriptioncodingYaoWangandQin FanZhu Proc ofIEEE 1998ErrorConcealmentMasahiroWada IEEEJSAC June1989OtherErrorRecoveryNEWPRED RESCUITUH 263 InjonRheeandSrihnathR Joshi IEEEJSAC2000 11 LinkLayer TransportLayer TransportLayer LinkLayer MediaLayer MediaLayer PhysicalNetworkChannel ECC ARQ FEC Hybrid NEWPRED RESCUE Multi layercoding Videoframes ErrorResilienceinMultimediaStreaming LayersofErrorResilienceforMultimediaStreamingTransport layererrorcontrolendeavorstorestorethelosswithoutalteringthedata Media layererrorrecoverywillaffecttheplaybackqualitymoreorlesswhiletransport layererrorcontrolfails ErrorConcealment ErrorConcealment MultipleDescriptionCoding HFEC 12 ARQ C PapadopulousandG Parulkar NOSSDAV 1996PlaybackbufferatreceiverIncreasetimeavailableforrecovery Sender sretransmissionbufferAvoidretransmissionofpacketwouldarrivelate ConditionalretransmissionSenderabortsretransmissionrequestifit stoolate Gap basedlossdetectionReceiversendsNAKonly Keepdataintegrityinformationtoaidfurtherprocessing e g concealment recovery MultipleRetransmissionsSchemeRetransmissionrequestanddatamaybelostagain IfRTDissmall It sfeasibletoperformmultipleretransmissionsforthelostpacketinordertoimproveperformance FEC 13 FECopensourcelink http planete bcast inrialpes fr article php3 id article 7 14 HybridARQ RetransmitthesamedatawithFECcode H DengandM Lin IEEETrans Comm 1990NoFECinthefirsttransmission butthesendermustretransmittheFECcodeincaseofdataloss S LinandD Costello ErrorControlCoding Fund AndApp 1983 15 Transport layerErrorControls FECSusceptibletoburstlossprocessingoverheadforredundantcodeBandwidthoverheadinerror prunelink25 30 overhead Oguz95 ARQ retransmission Incursatleast1RTDNotpracticalformulticastconnectionHybridARQSuffercombinedweakness 16 Motivation Real timevideostreamingserviceVideoonDemandDistanceLearning etc Deliveringreal timevideodataoverpacketswitchnetworkStricttimingrequirementVulnerabletopacketlossErrorpropagation 17 Motivation ErrorControlARQ i e retransmission RoundTripDelay i e RTD MinimumcostofnetworkbandwidthTransmissionSchemeinReal timeVideoStreamingService NetworkCloud Videodatasender sendingrate arrivalrate player decoder playbackrate playbackbuffer 18 SystemComponentsforRetransmission basedErrorControl OriginalworkfromC PapadopulousandG Parulkar NOSSDAV 1996Gap basedlossdetectionMultiple RetransmissionsSchemeConditionalretransmission 19 Gap basedlossdetection ApacketlossisdetectedwhileitsnextpacketfirstarrivesinplaybackbufferReceiversendsNAKtothesender Receiver splaybackbufferIncreasetimeavailabilityforrecovery 20 Multiple RetransmissionsScheme Retransmissionrequestanddatamaybelostagain IfRTDissmall It sfeasibletoperformmultipleretransmissionsforthelostpackettoimproveperformance 21 Conditionalretransmission SenderabortsretransmissionrequestifalostpacketistoolatetoretransmitRetransmissionbufferatsender 22 Observations ARQforReal timeVideoStreamingPlaybackBufferOccupancyLargerdelaybudgetofthearrivalpacketintheplaybackbufferHighernumberofpossiblevalidretransmissionsRateControlSender ssendingratewillaffectthereceiver sarrivalrateThedifferencebetweenreceiver sarrivalrateandplaybackratewillaffecttherunningpositionofplaybackbuffer 23 ProposedErrorControlScheme Buffer controlledRetransmissionErrorControl BREC RetransmissionErrorControlSchemeGap basedlossdetectionandconditionalretransmissionMultipleretransmissionCall outqueueBufferPositionControlFeedbackratecontrolforplaybackbufferoccupancy 24 ControlModelofBREC BasicComponentsofRetransmission 26 MultipleRetransmissionswithCalloutQueue Whycall outqueue Needtimeoutschemetopredictwhentodetectthelossofretransmissionrequest i e NAK andretransmitteddataRTDMultipleretransmissionsneedimmediateaccessandresponseTimersystemcallisnotefficient especially itmaynotbefeasibleinsomeembeddedsystems TheoreticAnalysis MultipleretransmissionscansignificantlyreducethepacketlossratioifthePPD Packet sProcessingDeadline ismuchlongerthanRTD 28 MultipleRetransmissionswithCalloutQueue Anewnodeisappendedwhiledetectingaloss Eachnodehasbi directionlinks Counterfieldindicateswhentoissuetherequestforthelostpacketwithsequencenumber decreasesthecounterintheheadnode CountervalueindicatesarelativevaluetoitspreviousnodeAnodeisremovedwhilethearrivalofaretransmittedpacketortheRTDisnotallowedtoretransmitthenodeindexwillbespecifiedintheprotocolheader MultipleRetransmissionNeedsaneffectivetimer OriginalTimerSchemenewMRtimerO N removeMRtimerEarlyO N removeMRtimerLateO N renewMRtimerO 1 30 UDP IPHeader Sequencenumber RetransmissionFlag NodeIndexinM R queue MediaData M R MultipleRetransmissions i e call outqueue ProtocolHeaderinBREC ProtocolHeaderNodeIndexinM R queueindicatetheindextothecalloutqueueinreceiver ImprovedTimerScheme TimerActions newMRtimer removeMRtimerEarly removeMRtimerLateandrenewMRtimeractionsareO 1 32 FeedbackControlforPlaybackBufferOccupancy WeconsidermoreabouttheratechangeoftheplaybackbufferoccupancyBecausePcontrolistheoreticallyunstableConsiderthederivativepartRate SensitiveARQPDControl Controller Actuator Sensor Device feedback targetvalue a TypicalfeedbackcontrolSystem RateRegulator feedbackofbufferoccupancyb t Packetstream network b rate basedcontrolsystemwithbufferoccupancyfeedback server client 33 RateRegulatorwithFeedbackofBufferOccupancy ProportionalControl Pcontrol rMisthemaximumrateadjustmenttoreducethebursttraffictothenetwork IntuitivecontrolfunctionEquivalentblockdiagramofthePcontrol 34 Rate SensitiveARQ ARQ BufferPositionChangeRatePDcontroller ProportionalandDerivative tisthetimeintervaloffeedbackcontrol EquivalentblockdiagramofthePDcontrol rM sbm B s U s E s Kp Kds PDcontroller RateRegulatoruponBO 1 s 35 HowtopickupKpandKd rM sbm B s U s E s Kp Kds PDcontroller IntuitiveRateRegulator 1 s G s 36 HowtopickupKpandKd cont d tmaxisthetimetoreachthemaximumovershoot tmax T 2 TisthedampingcycleperiodBecause r t fromdifferentKpandKdwillexceed rMThemodifiedrateadjustmentfunction r t isthuswrittenasfollows 37 ExperimentsforBREC BRECclient1 PcontrolBRECclient2 PDcontrolNon BRECclient AIMDwithretransmissionwhilethepacketislostMaximumbandwidthis1 6MbpsInsertedRTDsare50ms 200ms 400ms 600msInsertedPacketLoss 0 001 0 005 0 01Assumefeedbackchannelisreliable DummyNetonFreeBSD4 0 BRECClient2 Non BRECClient VODServer Segment140 109 18 Segment140 109 21 BRECClient1 Dummynet networkdelay bandwidthandlossratio 38 TheClientsofSet topboxes 39 ExperimentalBackground ThevideoclipisMPEG 1 StarWars EpisodeI 20minuteslong motionpicturePlaybackbuffersizeis200Kbytes eachpacketis1Kbytes maximumrateadjustmentis1Kbytes s rM 1 Targetpositions100Kbm 100andtmax 1 5secondsKp 438Kd 418Onefeedbackcontrolintervalis3seconds t 3 SameasRTCPofRTP 40 ExperimentalBackground cont d Ineachexperiment werecordedNumberoflostpacketsandrecoveredpacketsReducedlossratioandImprovedratioNumberofburstlossandrecoveredburstlossBurstlossrecoveryratioNumberofmultipleretransmissionRatioofMultipleRetransmissionVariationsofsendingrateAveragesendingrateandPeaksendingrateRunningbufferoccupanciesToestimatebufferingdelay 41 BufferOccupancyControllability HistogramcurvesofbufferoccupancyNoinsertedlossNon BRECclientsendconstantrate AIMD 42 ImprovedRatiosandIncurredNetworkRates InsertedRTD50ms 200ms 400ms 600msTargetbufferingdelay500ms estimatedbufferingdelayistheobservedbufferingdelayInsertedloss0 001 0 005 0 01 43 BurstLossRecoveryandMultipleRetransmissions InsertedRTD50ms 200ms 400ms 600msTargetbufferingdelay500ms estimatedbufferingdelayistheobservedbufferingdelayInsertedloss0 001 0 005 0 01 44 IPBFramesIntegrityRatios InsertedRTD50ms 200ms 400ms 600msTargetbufferingdelay500ms estimatedbufferingdelayistheobservedbufferingdelayInsertedloss0 001 0 005 0 01 45 ConclusionsandFutureWork ExperimentsshowthatourschemesignificantlydecreasespacketlossandimprovesQoSEvenifaclient suchasset topbox PDAorcellularphone containsalimitedamountofplaybackbufferBRECcontributesainnovativewaytoresistthenetworkuncertaintywithminimaloverheadbyapplyingfeedbackcontroltheory 46 ConclusionsandFutureWork Retransmission basederrorcontrolisstillaprevalentandefficientmethodforreal timevideostreamingThemorethepacketlossarerecovered thebettertheplaybackqualitycanbeachievedTheproposederrorcontrolschemeisvalidatedbyanInteractiveTrueVODsystemThelossratecanbereducedbyanorderofmagnitudeMultiple retransmissionsschemeiseffectivelydeployedbycalloutqueueandMRfieldintheprotocolheader 47 ConclusionsandFutureWork BRECmaybeappliedfurtherforreal timevideostreamingoverwirelessnetworkespeciallywhilethemobileclientmovetoanewcellMayincurburstlossIntraframeismorevulnerableforlossNeedshigherpriorityShortenthetime outvalue i e zero incall outqueue 48 ConclusionsandFutureWork BRECschemecanbeusedwithotherreal timestreamingsuchasRTPprotocolst