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LOW-LATENCY VIDEO STREAMING LOW-LATENCY VIDEO STREAMING OVER PEER-TO-PEER NETWORKSOVER PEER-TO-PEER NETWORKSLOW-LATENCY VIDEO STREAMING LOW-LATENCY VIDEO STREAMING OVER PEER-TO-PEER NETWORKSOVER PEER-TO-PEER NETWORKS
Eric SettonEric Setton
Jeonghun NohJeonghun Noh
Professor Bernd GirodProfessor Bernd Girod
Information Systems LaboratoryInformation Systems LaboratoryStanford UniversityStanford University
22J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
MotivationMotivationChallenges of P2P streaming• Limited bandwidth • Unreliable peers
Related work• Tree-based p2p :
– End System Multicast (single tree) [Chu, Rao, Zhang, ACM SIGMETRICS 2000]– COOPNET (central server, multiple trees)
[Padmanabhan et all, NOSSDAV, 2002]
• Mesh-based (Gossip-based) p2p :– Coolstreaming
[Zhang, Liu, Li and Yum, MMSP & INFOCOM 2005]
Our Goal : Low-latency P2P video streaming
33J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
• Low-latency P2P protocol– Join / rejoin procedure– Experimental setup– Performance
• Prioritized transmission– Content / network-aware prioritization– Simulation Results
OutlineOutline
44J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
Multiple Tree ConstructionMultiple Tree Construction
… …Video stream
55J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
Join ProcedureJoin Procedure
Initial join• Contact video source• Receives peer list, number of trees
Probe peers
Connect to multicast trees• Parent selection factor
– Available bandwidth– Minimize tree height– Maximize diversity
… …Video stream
66J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
Disconnect / Rejoin ProcedureDisconnect / Rejoin Procedure
3 trees
Parent of yellow tree is down
Yellow tree is down?
Parent leave is detected
Retransmissions requested
Yellow tree is recovered
77J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
Experimental SetupExperimental Setup• Network/protocol simulation in ns-2
– 300 active peers – Random peer arrival/departure
average: ON (4.5 min) / OFF (30 sec)– Typical access bandwidth distribution – Over-provisioned backbone– Delay: 5 ms/link + congestion
• Video streaming– H.264/AVC encoder @ 250 Kb/s– 15 minute live multicast
[Sripanidkulchai et al., 2004]
Downlink Uplink Percentage
512 Kb/s 256 Kb/s 56% 3 Mb/s 384 Kb/s 21%1.5 Mb/s 896 Kb/s 9% 20 Mb/s 2 Mb/s 3% 20 Mb/s 5 Mb/s 11%
Downlink Uplink Percentage
512 Kb/s 256 Kb/s 56% 3 Mb/s 384 Kb/s 21%1.5 Mb/s 896 Kb/s 9% 20 Mb/s 2 Mb/s 3% 20 Mb/s 5 Mb/s 11%
88J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
Join and Rejoin LatenciesJoin and Rejoin Latencies
Simulations over ns-2, 300 peers
Number of trees: 3
Retransmissions enabled
Simulations over ns-2, 300 peers
Number of trees: 3
Retransmissions enabled
99J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
Protocol ScalabilityProtocol Scalability
Simulations over ns-2
Video traffic
Control traffic
Protocol overhead
Simulations over ns-2
Video traffic
Control traffic
Protocol overhead
1010J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
Benefit of DiversityBenefit of Diversity
Downlink Uplink PercentageNumber of average supportable peers
1 tree 2 trees 3 trees 4 trees
512kb/s 256Kb/s 56% 0 0.5 0.7 0.75
3Mb/s 384Kb/s 21% 1 1 1 1.25
1.5Mb/s 896Kb/s 9% 3 3 3 3
20Mb/s 2Mb/s 3% 6 6.5 6.7 6.7
20Mb/s 5Mb/s 11% 17 17 17 17
Number of
average supportable peers2.5 2.8 2.9 3.0
Distribution of peer bandwidth
Video encoding rate : 250 Kb/s
Over-provisioning factor : 15%
Distribution of peer bandwidth
Video encoding rate : 250 Kb/s
Over-provisioning factor : 15%
1111J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
Benefit of DiversityBenefit of Diversity
1212J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
• Scheduler iteratively selects
Network / Content-Aware PrioritizationNetwork / Content-Aware Prioritization
Sender
PI B P B P B
7 1 6 1 4 1 2
1313J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
Number of trees: 4
Retransmissions enabled
Number of trees: 4
Retransmissions enabled
Network / Content-Aware PrioritizationNetwork / Content-Aware Prioritization
5dB
5dB
4dB
2.5dB
1414J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
Network/content aware prioritization33.71 dB
No prioritization30.17 dB
H.264 @ 250 Kb/swith 0.8 second playout deadline
36 Parallel Views out of 75 peers
1515J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
Network/content aware prioritization33.71 dB
No prioritization30.17 dB
H.264 @ 250 Kb/swith 0.8 second playout deadline
36 Overlapped Views out of 75 peers
1616J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
ConclusionsConclusions
• Peer-to-peer control protocol– Tested with up to 3000 peers in ns-2– Light-weight and scalable– Low start-up and tree repair time
• Network/content-aware prioritization– Adapts to packet importance and tree topology– Gains up to 5dB with small playout deadline
1717J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
Extra Peer Pool for Fast RejoinExtra Peer Pool for Fast Rejoin
Probes extra peers regularly
One of multiple trees
The red tree parent leaves
Chooses a new parent
Advantage : - Keep Parent Diversity - Less packet drop
Disadvantage : - Increased control traffic - Weak to large-scale disconnect
1818J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
Receiver-Driven Content-Aware Receiver-Driven Content-Aware Retransmission RequestsRetransmission Requests
• Determine missing packets• Iteratively request most important packet• Limit number of unacknowledged retransmissions
P
PI B B P ……
Parent 1
Parent 2 fails
Video Buffer
Child
1919J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
% peersconnected to all 4 trees
% peersconnected to all 4 trees
With content-oblivious retransmissions
Without retransmissions
Content-Oblivious RetransmissionsContent-Oblivious Retransmissions
2020J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
% peersconnected to all 4 trees
% peersconnected to all 4 trees
With receiver-driven CoDiO light
Without retransmissions
Receiver-Driven Content-Aware Receiver-Driven Content-Aware RetransmissionsRetransmissions
2121J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
Video and Network Aware DesignVideo and Network Aware Design
• Child peers (Receivers)– Receive video stream from parent peers– On requesting retransmissions
• Compute expected video quality improvement• Compute expected network congestion
• Parent peers (Senders)– Send video stream to child peers– On scheduling packets to transmit
• Compute importance of each packet• Compute expected network delay
2222J. Noh et al. : Low Latency Video Streaming Over Peer-To-Peer Networks July 10 2006
Benefit of DiversityBenefit of Diversity
Video source : 250kbps (Mthr & Dthr)
Retransmissions enabled
Video source : 250kbps (Mthr & Dthr)
Retransmissions enabled