Playbackbuffer Equalization for Streaming Media using Stateless Transport Prioritization

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Playback-buffer Equalization for Streaming Media
using Stateless Transport Prioritization

• Dan Tan, HPL, Palo Alto
• Weidong Cui, UC Berkeley
• John Apostolopoulos, HPL, Palo Alto

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Reducing Pauses in Playback

• Problem frequent pauses in playback
• Goal reduce pauses via smart routing in common
  bottleneck
• Client transparency
• No server coordination
• Stateless smart routing in bottleneck

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How Pauses Occur
No Control
Received network condition
Consumed constant
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Our Solution
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Testbed
Encoding buffer Occupancy into TOS in IP header
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Label
7
6
5
4
3
2
0
0
2
4
8
16
32
64
Buffer occupancy (s)
Smart Router - mostly priority queuing
(smallest b first) - every 20 packets perform
round-robin
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Results First-In-First-Out (FIFO)
Buf data
deadline
pause
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Results Playback Buffer Equalization (PBE)
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Simulation Study

• More control in size and parameters of topology
• Large number of runs
• Various simulated load by adjusting Poisson
  arrival rate of independent sessions,
• Media duration according to empirical
  distribution of trace from HP Media Services

80 ms
40 ms
bottleneck
20 ms
10 Mbps
Servers
Receiver
10 ms
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Results NS Simulation Results
FIFO
pauses
Improves fairness!
PBE
pauses
load
Moderate load
Over-load
no reduction
10x reduction
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Other Characteristics

• No harmful effects over non-bottleneck links
• Reduction factor in pauses roughly constant and
  independent of round-trip delay
• Other Smart Router designs examined

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Summary

• Playback Buffer Equalization (PBE)
• Reduces pauses for sessions behind a common
  bottleneck
• Client-transparent
• No server coordination
• Stateless operation at Smart Router
• Experiments simulations for TCP (HTTP)
  streaming
• Future Work
• Using existing QoS mechanisms in current
  switches, e.g, HP Procurve 530x series switches
• Extension to non-TCP rate control