Media‐AwareNetworkElementsonLegacyDevices

IngoKofler,RobertKuschnig,andHermannHellwagnerChris:anTimmerer

KlagenfurtUniversity(UNIKLU)FacultyofTechnicalSciences(TEWI)DepartmentofInforma:onTechnology(ITEC)Mul:mediaCommunica:on(MMC)

h;p://research.@mmerer.comh;p://blog.@mmerer.commailto:chris@an.@mmerer@itec.uni‐klu.ac.at

m16695

Acknowledgement:PartofthisworkissupportedbytheEuropeanCommissioninthecontextoftheandENTHRONE(contractno.038463)project.Furtherinforma@onis

availableath;p://www.ist‐enthrone.org.

Outline

•  Mo@va@onandIntroduc@on

•  ListofTechnologies

•  ArchitectureandPerformanceEvalua@ons

•  DemoVideo

•  Conclusions/References

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Mo@va@onandIntroduc@on

•  Adapta@onofanSVCbitstream–  AchievedbyremovingcertainNALUs➙filteringofNALUs–  Steeredbya(TID,DID,QID)tuple➙filtercriteria–  Computa@onallycheap(comparedtotranscodingetc.)

•  Idea–  Performreal‐@mein‐networkadapta@onoftheSVCbitstream

onanordinary,low‐costWiFirouter–  Media‐awareNetworkElement(MANE)

•  Applica@onsofin‐networkadapta@on–  Cross‐layeradapta@onontheaccesspoint–  Adapta@onfordifferentend‐devices

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Media‐awareNetworkElement

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On‐the‐flyadapta@onofscalablecodedvideocontentinamedia‐awarenetworkelement(MANE).

Source:h;p://ip.hhi.de/imagecom_G1/savce/

ListofTechnologies

•  ScalableVideoCoding(SVC)•  Real‐@meStreamingProtocol(RTSP)

–  Establishingandcontrollingthestreamingsession–  VCR‐likecontrolofthestreaming(Start,Stop,Pause)

•  Real‐@meTransportProtocol(RTP)–  Encapsulatesthevideoand/oraudiocontent– MostlyusedontopoftheunreliableUDPprotocol– Offerssequencenumber,@mestampsforsyncingtheplayback

– Genericheaderwithcontent‐specificpayloadformat(AVC,SVC,…)

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Proxy Approach

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•  Proxy on network device between client & server –  Intercepts the RTSP / RTP communication –  Proxy is transparent for the client –  Acts as client for initial server and as server for the client

•  Implications –  Proxy has to modify parts of the request (e.g. port numbers) –  Proxy can then adapt the SVC video stream carried over RTP

server

RTSP RTP/RTCP

TCP UDP

IP

MAC/PHY

client

RTSP RTP/RTCP

TCP UDP

IP

MAC/PHY

router

IP

MAC/PHY

routerwithproxy

RTSP RTP/RTCP

TCP UDP

IP

MAC/PHY

Proxy Approach (cont’d)

Benefits

•  Session‐andstream‐/media‐awareness

•  Enablesstatefulinspec@onandprocessingofpackets

•  Allowsadapta@ononaper‐sessionbasis

•  ConsistentRTCPreceiverandsenderreports

Drawbacks

•  Proxyisrunningasuser‐spaceprocess

•  RTPpacketshavetobepassed(copied)fromthekernel‐spacetotheuser‐spaceandviceversa

•  Decreasestheore@calthroughputcomparedtokernel‐internalsolu@on(e.g.filteringonIPlevel)

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Architecture

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HandlesincomingRTSPrequests(554redirecttoproxyusingiptables)

SDPstoredinLRU‐basedcacheun@lsessionestablished

Maintainsstate:seq#,@mestamps,SVCparams,monitoring,etc.

Forwardsnon‐SVCpacketsAdaptsSVCpackets

ActsasserverforclientActsasclientforserver

Retrievemonitoringinforma@onModifyadapta@on/SVCparameters

PerformanceEvalua@ons

•  Hardware:LinksysWRT54GL–  BroadcomSystem‐on‐ChipBCM5352EL– MIPS32200MHzCPU–  16MBRAM–  4MBFlashMemory–  IEEE802.11b/gWLAN–  FastEthernetswitchwith5ports–  price~45Euros(May2008)

•  Sonware:OpenWrt–  Linux‐basedfirmwareforBroadcom‐basedWiFirouters–  gcc-based SDK for OpenWrt available –  Proxyimplementa@oninANSIC

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PerformanceEvalua@ons(cont’d)

•  Evalua@onoftheimplementa@ononthetargetplaporm–  Server–proxy–clientdeployment–  Inves@ga@onofworst‐casescenario(noadapta@on)

•  Performancemetrics–  CPUusagefordifferentnumberofstreams–  Delayintroducedbytheproxyonacompleteaccessunit(frame)

•  ThreedifferentSVCstreamsforevalua@on–  Foreman,CIF,30Hz,715kbps–  City,4CIF,30Hz,1247kbps–  Harbour,4CIF,30Hz,2056kbps

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PerformanceEvalua@ons(cont’d)

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CPUUsage

PerformanceEvalua@ons(cont’d)

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CDF of delay for sequence city (1245 kbps)

DemoVideo

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Conclusions

•  Proxyapproachforin‐networkadapta@ononaper‐packetbasis–  Awareofsessionsandindividualstreams(media‐aware)–  Stateful,notasimplepacketdropper

•  Applica@ons–  Adapta@onaccordingtodevicecapabili@es–  Cross‐layeradapta@on–  NATtraversal

•  Performancesufficientfortypicalhomedeployments–  4parallelstreamswith30percentCPUloadand<100msdelay

➙SVCadapta@oncanbedoneonexis@ngoff‐the‐shelfnetworkdevices

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References•  I.Kofler,J.Seidl,C.Timmerer,H.Hellwagner,I.DjamaandT.Ahmed,

“UsingMPEG‐21forcross‐layermul@mediacontentadapta@on”,JournalonSignal,ImageandVideoProcessing,Springer,vol.2,no.4,Dec.2008.

•  R.Kuschnig,I.Kofler,M.Ransburg,H.Hellwagner,“Designop@onsandcomparisonofin‐networkH.264/SVCadapta@on”,JournalofVisualCommunica@onandImageRepresenta@on,Sept.2008.

•  I.Kofler,M.Prangl,R.Kuschnig,andH.Hellwagner,“AnH.264/SVC‐basedadapta@onproxyonaWiFirouter”,Proceedingsofthe18thInterna@onalWorkshoponNetworkandOpera@ngSystemsSupportforDigitalAudioandVideo(NOSSDAV2008),Braunschweig,Germany,May2008.

•  I.Kofler,C.Timmerer,H.Hellwagner,andT.Ahmed:“TowardsMPEG‐21‐basedCross‐layerMul@mediaContentAdapta@on”,Proc.2ndInterna@onalWorkshoponSeman@cMediaAdapta@onandPersonaliza@on(SMAP2007),London,UK,Dec.2007.

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Thankyouforyoura;en@on

...ques@ons,comments,etc.arewelcome…

Ass.‐Prof.Dipl.‐Ing.Dr.Chris@anTimmererKlagenfurtUniversity,DepartmentofInforma@onTechnology(ITEC)

Universitätsstrasse65‐67,A‐9020Klagenfurt,AUSTRIAchris@an.@mmerer@itec.uni‐klu.ac.at

h;p://research.@mmerer.com/Tel:+43/463/27003621Fax:+43/463/27003699

©Copyright:Chris.anTimmerer

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