Streaming Media Distribution Techniques

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Streaming Media Distribution Techniques

• Jie Huang

Class Presentation for CSE581 Internet Technology
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Papers

• Broadcasting on Isochronous channels
• Skyscraper Broadcasting A New Broadcasting
  Scheme for Metropolitan Video-on-Demand
  Systemsby Kien A. Hua and Simon Sheu, Univ. of
  Central Florida
• Scalable On-Demand Media Streaming with Packet
  Loss Recoveryby Anirban Mahanti, Derek L. Eager,
  Mary K. Vernon, and David Sundaram-Stukel, Univ.
  of Saskatchewan and Univ. of Wisconsin
• Caching in the Internet
• Caching Techniques for Streaming Multimedia over
  the Internetby Markus Hofmann, T.S. Eugenne Ng,
  Katherine Guo, Sanjoy Paul, and Hui Zhang, Bell
  lab and Carnegie Mellon Univ.

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Measurements for Video-on-Demand

• Server bandwidth
• Client bandwidth
• Client buffer space
• Startup Latency

4
Broadcasting Schemes

• Periodic Broadcast
• Server centered (server bandwidth)
• Pyramid Broadcasting (PB)
• Permutation-Based Pyramid Broadcasting (PPB)
• Skyscraper Broadcasting (SB)
• Reliable Periodic Broadcast (RPB)
• Bandwidth Skimming
• A client merging technique, client centered
  (client bandwidth, startup latency)
• Simple Bandwidth Skimming
• Reliable Bandwidth Skimming

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Pyramid Broadcasting
1 a a2 a3
a4
Video 1
1
2
3
4
5
Video 2
1
2
3
4
5
Channel bandwidth
Server bandwidth
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Pyramid Broadcasting (cont.)

• At the client side
• Download the next segment at the earliest
  possible time after beginning to play the current
  segment
• Play time for segment i must be longer than the
  longest waiting time for the start of segment i1
• At most two concurrent channels! Channel
  bandwidth gt play rate
• High network and disk bandwidth
• Large buffer, 70 of the length of the video

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Permutation-based Pyramid Broadcasting

• Smaller transmission bandwidth reduces disk
  bandwidth and space requirement
• Large latency
• Number of channels is limited to 7

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Skyscraper Broadcasting
1 2 2
5 5
Video 1
Video 2
Channel bandwidth play rate
Even group
Odd group
Server bandwidth
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Skyscraper Broadcasting (cont.)

• At the client side
• Receiving segments in terms of transmission group
• A group consists of consecutive segments having
  the same sizes
• A group is downloaded in its entirety, in the
  segment order

• At most two groups are being downloaded at the
  same time
• Maximum bandwidth requirement 2 play rate
• Maximum buffer space longest segment size
  first segment size

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Skyscraper Broadcasting (cont.)

• Segment size restriction
• No segments larger than W times the size of the
  first segment
• Small buffer space prefers small W
• (W-1) first segment size
• Low startup latency prefers large W
• large W means small first segment size

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Skyscraper Broadcasting (cont.)

• Choosing W allows flexibility
• achieve latency of PB and buffer space of PPB

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Reliable Periodic Broadcast

• Loss Recovery
• Digital Fountain loss recovery without
  retransmission

Any four packets received
d
b
c
f
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Reliable Periodic Broadcast (cont.)

• Each segment is delivered by an approximation of
  a digital fountain
• Receive an entire segment before playing it
• ! latency performance is competitive with
  Skyscraper
• Low latency comes from
• A client can begin receiving immediately
• The maximum possible segment size increase
• The client will receive an entire segment just in
  time to begin playing it

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Reliable Periodic Broadcast (cont.)

• Comparison with Skyscraper
• K total number of segments number of channels
  available for a video sever bandwidth Kr
• r segment transmission rate (in playback
  rate)
• s maximum number of streams clients listen to
• lk length of the kth segment relative to segment
  1
• D video length (in playback time)
• D1 segment 1 length (in playback time)
• r 1, s 2 in Skyscraper, which makes the RPB
  length progression a Fibonacci series.

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Reliable Periodic Broadcast (cont.)

• Latency depends on D1
• SB D1/2
• RPB D1
• D1 D / Slk
• For a certain server bandwidth, K is fixed
• So D1 depends on how the segment sizes increase

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Reliable Periodic Broadcast (cont.)

• Price of low latency
• Buffer size

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Bandwidth Skimming

• Client merging a new client listens to its own
  new stream as well as the most recently initiated
  on-going stream that it can merge with.

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Bandwidth Skimming (cont.)

• Emphasis on client bandwidth lt 2play rate
• e.g. client bandwidth 1.33play rate in 4
  channels

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Bandwidth Skimming (cont.)

• Reserve a small skim of client reception
  bandwidth to support substantial reduction in
  server and network bandwidth
• Skim can be tuned to provide the trade-offs
  between playback quality and required server
  bandwidth

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Reliable Bandwidth Skimming

• Divide the media stream into segments that have
  fixed duration
• Each segment is stretched using erasure codes
• For each segment, the server transmits a rate 1.0
  primary stream and a rate p/(1-p) secondary
  stream
• The secondary stream is offset in time by the
  segment duration
• Merge secondary streams as well as the primary
  streams

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Caching Techniques for Streaming Media

• Segmentation of Streaming Objects
• rather than all-or-nothing
• Dynamic Caching
• like a ring buffer
• Self-organizing Cooperative Caching
• helper machines inside the network

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Summary

• Broadcasting schemes
• Periodic Broadcast
• Pyramid Broadcasting (PB)
• Permutation-Based Pyramid Broadcasting (PPB)
• Skyscraper Broadcasting (SB)
• Reliable Periodic Broadcast (RPB)
• Bandwidth Skimming
• Simple Bandwidth Skimming
• Reliable Bandwidth Skimming
• Caching techniques for streaming media