GnuStream: a P2P Media Streaming Prototype

1
GnuStream a P2P Media Streaming Prototype

• Xuxian Jiang, Yu Dong, Dongyan Xu, and Bharat
  Bhargava

2
Outline

• Introduction
• System Overview
• Design and Implementation
• Experiments
• Conclusions and Comments
• Q A

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Introduction

• Video retrieving over P2P
• Traditional way open-after-downloading
• Streaming (Goal) play-while-downloading
• Challenges
• Stringent timing constraint
• Involve a set of peer senders
• P2P dynamic nature online/offline

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Recent Works

• Narada and PeerCast
• Synchronous broadcast of live media
• Not consider the limited contribution of
  bandwidth from individual peers
• CoopNet
• Builds multiple distribution trees
• Each receiver is required to consult the source
  node for upstream senders
• ZIGZAG
• Builds multicast tree based on hierarchy
• Assumes each peer only receives from one sender

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System Environment
Gnutella lookup service locates 4 candidate
senders (P2-P5)
(bandwidth indicated by the edge thickness)
P1 is looking for media file X
Standby sender
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System Features

• Integration with P2P lookup substrate
• Multi-sender aggregation
• Even allocation
• Proportional allocation
• Receiver data collection
• Detection of peer status change
• Recovery from failure or degradation
• Buffer control

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Design Architecture

• Network Abstraction Layer (NAL)
• Provides generic and uniform interface of P2P
  lookup substrate
• Streaming Control Layer (SCL)
• Deals with the dynamics and heterogeneity of P2P
  networks
• Bandwidth aggregation, data collection, status
  change detection and recovery, etc
• Buffer management
• Media Playback Layer (MPL)
• Media quality adaptation

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Implementation

• Using Microsoft Visual C 6.0
• Build from Gnucleus, a open source Gnutella
  client
• Buffer management is the most challenging aspect

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Implementation
Double buffering
SCL adjusts feeding rate to Decoder and thus the
display frame rate is tunable
Maintains some pointers to enforce the real-time
property of media streaming
Eliminate data overflow and underflow and smooth
the arrival jitter
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Experiments

• Local experimental testbed
• Desktop PCs with XEON CPU 2GHz, 1G Ram, 100Mbps
  Ethernet controller
• Limit the maximum upstream bandwidth to 60KB/s

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P2P streaming session setup
Frame size playback rate YUV sampling Bits per pixel Compression Rate
352 240 30 fps 420 8 261
143KBps i.e. 3 peer senders of 60KBps
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Buffering for continuous media playback

• Suppose AFR25fps, No. of Frames1680, then
  Initial Delay11.2sec.
• In addition, if the aggregate bandwidth
  (360KBps) is greater than the playback rate
  (143KBps), each sender will exploit the residual
  bandwidth to pre-transmit

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Peer failure detection and recovery
Turn off peer 3 at 27th second
Take approx. 1 sec to detect and recovery
Replaced by peer 4
No interruption to playback due to buffer control
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Conclusions

• GnuStream is a P2P and receiver-driven media
  streaming system
• Deployable in Gnutella network
• Open source
• Aggregate streaming capacity of individual peer
  senders
• Self-monitoring and adjustment in peer failure
  and bandwidth degradation
• The effectiveness of buffer control in
  maintaining both continuity and quality
• Experiments on LAN

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Comments

• The first streaming implementation on an existing
  P2P network
• However, important details are not mentioned
• E.g. how the senders coordinate?
• Experiments only in a small, local and homogenous
  network
• Bandwidth variation?
• Share bottleneck?
• More vigorous change in the sender set?

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Questions and Answers

• Thank you

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Reference

• Xuxian Jiang, Yu Dong, Dongyan Xu, Bharat
  Bhargava "GnuStream a P2P Media Streaming
  Prototype" Proceedings of IEEE International
  Conference on Multimedia Expo (ICME 2003), July
  2003
• http//www.cs.purdue.edu/homes/jiangx/GnuStream