Enabing Adaptive Video Streaming in P2P Systems

Dan Jurca, Jacob Chakareski, Jean-Paul Wagner, and Pascal Frossard,Ecole Polytechnique Federale de Lausanne (EPFL)

Director Reporter M9656008 M9656015 M9656019 M9656027 M9656034 M9656036

IEEE Communications Magazine June 2007

** P2PP2PP2PP2PP2POutLine

P2Ppeer to peer)p2pBTEmuleEzpeerKazzaeDonkey

**P2P

**P2PP2PP2P,P2P,P2P,P2P,,

**P2P

BitTorrentP2P,PPLive . 2004, ,200 300kbps~400kbp wmvrm PPStream 2005 300~440kbps wmvSopcast 200412, Streaming over P2P 300kbps~400kbpTVants 2005, ,

**

**

**

**Layered Encoding MDC (Multiple Description Coding)

**P2P(Overlay Network)

P2P(pear-to-pear)

**P2PP2PP2P

**P2PP2PP2P

**P2PP2P pearpear

**P2PP2P pearpear

P2P peerrequestserver Serverpeer server

**P2PAs a P2P system does not provide any guaranteed support to streaming services.

Two main types :Tree-based overlayMesh overlay

**P2PTree-based overlays organize the peers as a single or multiple tree overlay that connects the source of the media content to the clients.

**P2PSingle tree have fundamentally limited by the following two factors:

The high rate of peers joining/leaving the system.The received media quality is limited by the minimum upload bandwidth of the intermediate peers in the branch.

**P2PMultiple tree architectures address the aforementioned problems.

Multiple tree designing and maintaining such systems becomes less trivial.

Most importantly, the underlying physical topology must be carefully considered to achieve efficient content dissemination .

**P2PMesh overlay architecture is based on self organization of nodes in a directed mesh that is used for media delivery to clients.

**P2PThe advantages of mesh overlay architecture

Low cost and simplicity of structural maintenance . In the resilience of the topology to node failure or departure.

**P2PStreaming applications over such architectures faces important challenges.

Packet dissemination and data requests must follow closely the temporal ordering of the content at the source . The limited look-ahead content availability.

**H.264/AVCITU-T VCEGISO MPEG(Joint Video TermJVT)ITU-TH.264

(Video Coding LayerVCL)(Network Abstraction LayerNAL)

H.264/AVC

**H.264/AVC (Network Abstraction LayerNAL)H.264/AVC

H.264/AVC

H.264/AVC

**H.264/AVC (Video Coding LayerVCL)

H.264/AVC

**Scalable Video Coding(SVC) SNR / temporal / spatial / complexity / region-of-interest / object-based combined scalability graceful degradationbase-layer interlaced video

**Scalable Video Coding(SVC)SVCcumulated video streamsBase Layer (BL)Enhancement Layer 1 (EL1)Enhancement Layer 2(EL2)Base LayerEnhancement Layer1Enhancement Layer2

Scalable Video Coding(SVC)**

Scalable Video Coding(SVC)SVC**

**MPE - FEC MPE : Multi protocol EncapsulationContainer for upper layer protocols (IP,LLC/SNAP)Optimized for IP over DVB Associated with FEC in the DVB-H standard FEC : Forward Error CorrectionExtra layer added to provide error correctionBased on a Reed Solomon code RS (255,191)

MPE - FEC

**MDC (Multiple Description Coding)Multiple Description Coding (MDC) is a coding technique which fragments a single media stream into n independent sub streams (n >= 2)

MDC (Multiple Description Coding)Multiple Description

**MULTI-PATH STREAMING IN MESH NETWORKSP2P network multi-path,media applications

Multiple transmission pathsAggregated network bandwidthPacket loss de-correlationDelay reduction

** Clientdistinct network pathssource node

Streaming applicationrate allocationsubset of pathspossible sourcesAvailable path bandwidthError ratesMedia specific parameters

**media qualitysource selectionmedia rate allocationP2Pchannelpathpath re-computationadaptation of the media application

**RECEIVER-DRIVEN STREAMING SCENARIOSReceiver-driven streamingclinetstreamingSource peer selectionrate allocation

P2PClinetcandidate source nodes

**RCTP reportsconstruct a timely image of the available network topologyapplication adaptation

**DISTRIBUTED PATH COMPUTATIONReceiver-driven scenariosRequirement for full topology knowledge at a single peer (client)ReceivertopologyMake an optimal decisionpeerend to endcumbersomeincreasingly expensive or inefficient

**Augmenting the streaming scenario with intermediate peer functionality enables the maintenance of up-to-date information about network availabilityThe topology information is no longer relayed toward a single nodeevery intermediate peer makes an individual routing decision

**Distributed path computationSub-optimal streaming strategies

Heterogeneous network peer

**media application flexibility and convergence time of the solution

**Routing of media packets in tree-based overlaysStraightforwardIt is given directly by the structure of the multicast trees

**RATE-DISTORTION EFFICIENT SCHEDULING Packets of a media stream do not contribute to the video quality at a receiving peer, only if:It arrives prior to its delivery deadline; All the previous packets required for its correct decoding were received already.

**RATE-DISTORTION EFFICIENT SCHEDULINGvideo-on-demand(VoD) The benefit of each individual media packet can be computed and stored before the streaming session actually begins.

**VODvideo on demand

client/serverVODCDNcontent delivery network

**P2P VODP2P approach can potentially solve many serious problems posed in existing VoD systems including-The infeasibility of IP Multicast. -Network bottleneck at the video server.-The high maintenance/deployment of dedicated overlay routers.

-Media Server Farm1.unicast

2. (ServerCluster) streaming (bottolneck)

3.(load balancing)

-Content Delivery Network 1. (EdgeServer)

2.IPTV

3.

**P2P P2P (OverlayNetwork)

**P2P

**P2P Live StreamingP2Plivestreaming 1.P2P(OverlayNetwork) 2. 3.

**

**Packet scheduling and queue management techniques

They can be enabled in video distribution trees, with the goal of distributively adapting the streaming process to the available network resources.

**

**CODING FOR DISTRIBUTED DELIVERYChannel codes can be employed to encode independent segments of a video stream, such as GOP (group of pictures)

propose to encode the substreams of a scalable video bitstream using Raptor codes.

**Digital Fountain CodesDigital Fountain:Source splits message into smaller data symbolsData symbols are encoded into codewordsPotentially infinitely many unique codewordsClients can decode original data with sufficiently many unique codewordsLow overhead erasure resistant channel codes

**Luby Transform (LT) CodesRateless erasure codes LT Codes are universal in the sense that theyAre near optimal for every erasure channelAre very efficient as the data length grows.

**Erasure Codes: LT-Codesb1b2b3b4b5F=n=5 input blocks

**LT-Codes: Encodingb1b2b3b4b5c1Pick degree d1 from a pre-specified distribution. (d1=2)Select d1 input blocks uniformly at random. (Pick b1 and b4 )Compute their sum (XOR).Output sum, block IDsE(F)=F=

**LT-Codes: EncodingE(F)=

**LT-Codes: DecodingReceiver

**Raptor CodesIf pre-code is chosen properly, then the LT-distribution canhave constant average degree, leading to linear time encoding.

Raptor Code is specified by the input length , precode and output distribution .

X

**P2P streaming systems characteristics

**P2P,,.

routing selectionrate allocation ,media quality.

Reducing the real-time computational burden by the distributed algorithms can maximize the quality of the received video stream.

Conclusions

**REFERENCES

X. Zhang et al., Coolstreaming/DONet: A Data-Driven Overlay Network for Efficient Live Media Streaming, Proc. IEEE INFOCOM, vol. 3, 1317, Mar. 2005, pp. 210211.V. N. Padmanabhan, H. J. Wang, and P. A. Chou,Resilient Peer-to-Peer Streaming, Proc. IEEE ICNP, Atlanta, GA, 2003. N. Magharei and R. Rejaie, Understanding Mesh-Based Peer-to-Peer Streaming, Proc. ACM NOSSDAV, Newport, RI, 2006.Y. Shen et al., Peer-Driven Video Streaming: Multiple Descriptions Versus Layering, Proc. IEEE ICME, Amsterdam, The Netherlands, 2005.

**~ The End ~

Thank you for your attention!

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