Internet Streaming Media Delivery:

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Delving into. Internet Streaming Media Delivery:. A quality and Resource Utilization Perspective. Zhen Xiao Joint work with Lei Guo, Enhua Tan, Songqing Chen, Oliver Spatchcheck, and Xiaodong Zhang. ACM SIGCOMM Internet Measurement Conference (IMC'06), October 2006. - PowerPoint PPT Presentation


  • Internet Streaming Media Delivery:Zhen Xiao Joint work with Lei Guo, Enhua Tan, Songqing Chen, Oliver Spatchcheck, and Xiaodong ZhangDelving intoA quality and Resource Utilization PerspectiveACM SIGCOMM Internet Measurement Conference (IMC'06), October 2006

  • Multimedia on the InternetEducation and research

    News media

    Entertainment and gaming


  • Streaming MediaCDN/MDNStreaming server

  • Pseudo StreamingHTTP fileWeb server

  • Streaming MediaThousands of concurrent streams

    Flexible response to network congestion

    Efficient bandwidth utilization

    High quality to end users

    Challenges and techniques

  • Existing MeasurementsAccess pattern and user behaviorsA bunch of measurement studiesServer clusters, media proxies

    Streaming mechanism and delivery qualityFew studies

    Traffic volume Downloading > pseudo streaming > streaming (WWW05, cookie talk 2005)P2P >> all other media delivery systems

  • Our MeasurementInvestigate modern streaming servicesThe delivery quality and resource utilization

    Collect a large streaming media workload From thousands of home users and business usersHosted by a large ISPPacket level instead of server logs

    Analyze commonly used streaming techniquesAutomatic protocol switchFast StreamingMBR encoding and rate adaptation

  • OutlineTraffic overview

    Protocol rollover

    Fast Streaming

    Rate adaptation


  • Traffic OverviewUser communitiesHome userBusiness user

    Media hosting servicesSelf-hostingThird-party hosting

  • Number of requestsBusiness users access more audio than home users

  • On-demand media: File length Business users tend to access longer audio/video filesAudioVideopop songsmusic previews

  • On-demand media: Playback duration Business users tend to play audio/video longer AudioVideopop songsmusic previews

  • Live media: Playback duration Business users tend to access live audio/video longerAudioVideo

  • Traffic OverviewUser communitiesHome userBusiness userWorking environment affects access pattern

    Media hosting servicesSelf-hostingThird-party hostingNews and entertainment sites

  • Traffic OverviewUser communitiesBusiness users tend to access streaming media longer than home usersWorking environment affects access pattern

    Media hosting servicesSelf-hostingThird-party hosting

  • Media hosting services

  • OutlineTraffic overview

    Protocol rollover

    Fast Streaming

    Rate adaptation


  • Protocol RolloverStreaming serverRTSP/UDPRTSP/TCPHTTP/TCPEmbed RTSP commands in HTTP packetsMedia playerTraffic volume:UDP: 23%TCP: 77%HTTP: rare

  • Protocol rollover timeWindows media serviceRealNetworks media serviceProtocol rollover increases user startup time significantlyStartup latency = protocol rollover time + transport setup time + startup buffering time

  • Protocol selection and rollover avoidanceMost streaming traffic are TCP-basedThe usage of NAT?MMS clients report private IP address in clear textHome user: 98.3% report 192.168.*.*Business user: 89.5% report 192.168.*.*

    Protocol rollover sessions are minorHome user: 7.37%Business user: 7.95%

    Most streaming sessions use TCP directlyWhy?

  • Protocol selection and rollover avoidanceWindows media serviceSpecify the protocol in the media meta fileUse URL modifiers to avoid protocol rolloverEx: rtspt:// than 70%RealNetworks media serviceNAT transversal techniques

  • OutlineTraffic overview

    Protocol rollover

    Fast Streaming

    Rate adaptation


  • Fast StreamingFast Streaming: deliver media data faster than its encoding rateFast startFast cacheFast recoveryFast reconnectAlways TCP-based

  • Media objects delivered with Fast Cache(VoD home user workload)File lengthEncoding rateFast Cache is more widely used for media files with longer length and higher encoding rate.

  • Bandwidth UtilizationPLAY RTSP/1.0Bandwidth: 1.12 MbpsSpeed: 20.5RTSP /1.0 200 OKSpeed: 5Fast CacheNormal TCP

  • Fast Cache smooth bandwidth fluctuationRebuffer ratio = rebuffer time / play timeFast CacheNormal TCP

  • Fast Cache produces extra trafficMost streaming sessions only request the initial part of a media objectOver supplied dataFast Cache: 55%Normal TCP: 5%

  • Server response timeThird party media serviceSelf-hosting media serviceDESCRIBE foo.wmv RTSP/1.0RTSP /1.0 200 OKSDPRTTSRTsniffer

  • Server LoadWindows media load simulatorWindows Server 2003Win XPServer logEthernet 1 X 4 XSome CDNs/MDNs do not support Fast Cache at all

  • OutlineTraffic overview

    Protocol rollover

    Fast Streaming

    Rate adaptation


  • Rate Adaptation 96Kbps128Kbps320Kbps 1.128MbpsMultiple-bit-rate encodingStream switchWM: Intelligent streaming RM: SureStreamStream thinning: deliver key frame onlyVideo cancellation

  • MBR encodingon-demand audiolive audioaudio stream in video objectsvideo stream in video objects42% on-demand video are MBR encoded

  • Stream switch30 sec60%Streaming switch latencyLow quality duration3 sec40%Play-out bufferStream switch is often not smooth

  • Stream thinning30 sec70%

  • Fast Cache and stream switch Do not work with each other: fewer stream switches than MBR encoded objectsplayingbufferingplayingbufferingbufferingplaying5 secWhen network congestion occurs Like pseudo streamingWhen rebuffer occurstimefill play-out buffer

  • Streaming quality and playback durationHome userbusiness userLonger duration sessions have higher prob. of quality degradationBusiness user workload has more quality degradation>100 sec88%

  • Streaming quality summaryThe quality of media streaming on the Internet leaves much to be improved

  • Coordinating caching and rate adaptationFast Cache: aggressively buffer data in advanceOver-utilize CPU and bandwidth resourcesNeither performance effective nor cost-efficientRate adaptation: conservatively switch to lower bit rate streamSwitch handoff latencyCoordinated StreamingUpper boundPrevent aggressive bufferingLower boundPrevent switch latency

  • Coordinated StreamingRebuffering ratioOver-supplied dataSwitch latency

  • ConclusionQuality of Internet streamingOften unsatisfactoryNeed to improve

    Modern streaming media servicesOver-utilize CPU and bandwidth resourcesNot a desirable way to improve quality

    Coordinated StreamingCombine merits of both caching and rate adaptationSimple but effective

    In 2000, 9,000 narrowband and 2,400 broadband video streams on a single physical server


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