Congestion-Distortion Optimized Peer-to-Peer Video Streaming

Eric Setton*, Jeonghun Noh and Bernd GirodEric Setton*, Jeonghun Noh and Bernd Girod

Information Systems LaboratoryInformation Systems LaboratoryStanford UniversityStanford University

* Recently joined HP Labs* Recently joined HP Labs

22E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming

• Motivation

• Optimized scheduling for peer-to-peer (CoDiO P2P)1. Prioritization algorithm: sender receivers

2. Retransmission scheduler: receiver senders

• Experimental Results– Comparison to state-of-the-art schedulers

– Benefits of adaptive scheduling on P2P streaming

OutlineOutline

33E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming

Prior WorkPrior Work

• TCP-friendly rate-control– Indicates average rate as a function of collected statistics– Does not indicate any particular schedule

• Rate-Distortion optimized scheduling (RaDiO)– Formalization of the multimedia scheduling problem– Adapted the framework to video streaming

• Congestion-Distortion optimized scheduling (CoDiO)– Congestion defined as end-to-end delay– Designed for throughput-limited streaming– Same R-D performance as RaDiO and ~40% less congestion

[Chou and Miao, 2001]

[Floyd et al., 1997]

[Kalman and Girod, 2003]

[Setton and Girod, 2004-2006]

44E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming

Video Multicast over P2P Networks Video Multicast over P2P Networks Challenges• Limited bandwidth • Delay due to multi-hop transmission• Unreliability of peers

Related work• [Chu, Rao, Zhang, 2000]• [Padmanabhan, Wang and Chou, 2003]• [Guo, Suh, Kurose, Towsley, 2003]• [Cui, Li, Nahrstedt, 2004]• [Do, Hua, Tantaoui, 2004]• [Hefeeda, Bhargava, Yau, 2004]• [Zhang, Liu, Li and Yum, 2005]• [Zhou, Liu, 2005]• [Chi, Zhang, 2006]

Our Approach• Build and maintain complementary

multicast trees• Adapt media scheduling to network

conditions and to content• Error resilience through retransmission

requests

… …Video stream

55E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming

Specificities of P2P MulticastSpecificities of P2P Multicast

Many-to-many transmission

Little or no feedback

Limited contentinformation

Low complexity constraint

Routing not imposed

66E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming

Principles of CoDiO P2PPrinciples of CoDiO P2P

Scheduler which combines

1. optimized prioritization algorithm

Decide which packets to send, when and to which peer, to maximize performance while limiting incurred congestion

Receiving peer

Receiving peer

Receiving peer

Sending peer

77E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming

Scheduler which combines

1. optimized prioritization algorithm

2. optimized retransmission requests

Decide which missing packets to request, when and from which peer, to maximize performance while limiting incurred congestion

Principles of CoDiO P2PPrinciples of CoDiO P2P

Sending peer Sending peer

Receiving peer

Sending peer

88E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming

• Scheduler iteratively selects

• Intervals between transmission sufficient to– Mitigate any congestion of the uplink– Reserve rate for control traffic

CoDiO PrioritizationCoDiO Prioritization

Sender

PI B P B P B

7 1 6 1 4 1 2

99E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming

Parent on multicast tree 2

P PI B B B P ……

Distortion-OptimizedDistortion-OptimizedRetransmission RequestsRetransmission Requests

• Determine missing packets• Iteratively request most important packet• Limit number of unacknowledged retransmissions

P PI B B B P ……

Parent on multicast tree 1

1010E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming

Server-Client Scheduler PerformanceServer-Client Scheduler Performance

Simulations over ns-2

2-hop network path, ACKs from receiver

Throughput: 400 kb/s, delay 50 ms, packet losses 2%

H.264 encoding

Simulations over ns-2

2-hop network path, ACKs from receiver

Throughput: 400 kb/s, delay 50 ms, packet losses 2%

H.264 encoding

Salesman @ 365 kb/sForeman @ 290 kb/s

1111E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming

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– 15 minute live multicast– CIF resolution– 16-frame GOP I-B-B-B-P…

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%

1212E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming

Benefits of Optimized Scheduling (I)Benefits of Optimized Scheduling (I)

SalesmanForeman

Simulations over ns-2, 300 peers

Number of trees: 4

Retransmissions enabled

Simulations over ns-2, 300 peers

Number of trees: 4

Retransmissions enabled

2 dB

1 dB

1313E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming

Benefits of Optimized Scheduling (II)Benefits of Optimized Scheduling (II)

Salesman @ 320 kb/sForeman @ 290 kb/s

Simulations over ns-2, 300 peers

Number of trees: 4

Retransmissions enabled

Simulations over ns-2, 300 peers

Number of trees: 4

Retransmissions enabled

4 dB5 dB

1414E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming

CoDiO P2P33.71 dB

No prioritization30.17 dB

0.8 second latency for all peers

Average Video Sequence for 64 Peers

1515E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming

P2P Video Multicast: 36 of the Peers

0.8 second latency for all streams

CoDiO P2P33.71 dB

No prioritization30.17 dB

1616E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming

ConclusionsConclusions

• Summary– Congestion-distortion optimized scheduling for P2P

1. Prioritization adapts to the content and to the network conditions

2. Distortion-optimized retransmission scheduler

– Largest gains when streaming• with short playout deadlines (up to 4-5 dB)

• close to throughput limit (up to 1-2 dB)

• Future work – Study P2P scheduling of scalable video– Release of a peer-to-peer streaming client