media-aware network elements on legacy devices
TRANSCRIPT
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Media‐AwareNetworkElementsonLegacyDevices
IngoKofler,RobertKuschnig,andHermannHellwagnerChris:anTimmerer
KlagenfurtUniversity(UNIKLU)FacultyofTechnicalSciences(TEWI)DepartmentofInforma:onTechnology(ITEC)Mul:mediaCommunica:on(MMC)
h;p://[email protected];p://[email protected]:chris@an.@[email protected]‐klu.ac.at
m16695
Acknowledgement:PartofthisworkissupportedbytheEuropeanCommissioninthecontextoftheandENTHRONE(contractno.038463)project.Furtherinforma@onis
availableath;p://www.ist‐enthrone.org.
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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/
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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
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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
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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
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PerformanceEvalua@ons(cont’d)
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CDF of delay for sequence city (1245 kbps)
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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.@[email protected]‐klu.ac.at
h;p://[email protected]/Tel:+43/463/27003621Fax:+43/463/27003699
©Copyright:Chris.anTimmerer
162009/07/01 Chris@anTimmerer,KlagenfurtUniversity,Austria