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PLANETE project presentation:. Scalable video distribution techniques. Laurentiu Barza. Sophia Antipolis 12 October 2000. Motivation. User behaviour: skewed access: Zipf Rule 20/80 desire rapid access may be willing to sacrifice access time and some interactivity for lower cost service

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scalable video distribution techniques

PLANETE project presentation:

Scalable video distribution techniques

Laurentiu Barza

Sophia Antipolis 12 October 2000

motivation
Motivation
  • User behaviour:
    • skewed access: Zipf Rule 20/80
    • desire rapid access
    • may be willing to sacrifice access time and some interactivity for lower cost service
  • Goal: scalable service that provides almost « true VoD » at a much lower cost
outline
Outline

Basic schemes:

  • Server-Push Broadcast

- Baseline

- DeBey

- Pyramid & Skyscraper

- Tailor-Made

  • Client-Pull with Multicast

- Batching

baseline broadcast scheme
Baseline Broadcast Scheme
  • Continuos multicast of hot videos
  • M videos
  • K channels
  • assign K/M channels to each video
  • schedule video start times
  • « pay-per-view » model
slide5

Baseline Broadcast

Length of Movie

3 channels/movie

debey broadcast
DeBey Broadcast
  • Split a video into N equal sized segments
  • Segment “m” is transmitted ONCE every “m” time
  • reduce the mean transmission rate
  • peak transmission rate very high
slide7

De Bey Broadcast

Channels

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pyramid broadcasting
Pyramid broadcasting
  • Split video into N segments of lengths L1,L2,…,Ln
  • L = L1+L2+…+Ln
  • Segment size: Li =  * Li+1
  • lower max access time than baseline scheme
  • the client has to listen 2 channels simultaneous
  • significant receiver buffering: up to 70% of video length
slide9

Pyramid Segmentation

Skyscraper segmentation

skyscraper broadcasting
Skyscraper Broadcasting
  • use relative segment size progression: 1, 2, 2, 5, 5, 12, 12, 25, 25, 52, 52…
  • requires less buffering than pyramid scheme
  • requires strict synchronization among the multicast channels
tailor made approach
Tailor-Made approach
  • Cover all possible design dimensions
    • server transmission rate
    • start-up latency
    • peak client recording rate
    • peak client storage requirements
  • Is a modification of de Bey:
    • all the segments have the same length but are transmitted continuously
slide12

Taylor-Made Approach

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slide13

Taylor-Made Approach

Channels

Client joins

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partial conclusion
Partial conclusion

Proposed schemes characteristics:

  • are server-push approach
  • are designed for hot video
  • vary the way they segment a video
  • trade-off server transmission rate, client IO bandwidth and client storage and recording requirements
  • have all non-zero start-up latency
client pull batching
Client-pull: Batching
  • delay request for a video until a certain number of requests for that video arrive before the video is delivered
  • batching is only effective for popular videos
  • reduce server and network resource requirements
  • start-up latency can be very high
    • popularity of required video
    • no. Of requests required to schedule a video
controlled multicast
Controlled multicast
  • Controlled Multicast = Batching + Optimal Patching
  • define a patch threshold that trades off the size of the patches and the frequency in which new multicast channels are initiated
catching
Catching
  • Server broadcast video via dedicated multicast channels
  • Client
    • immediately joins the appropriate multicast channel
    • requests to the server the missing first part of the video
  • Server sends the first part to the client via a dedicated unicast channel
multicast with caching mcache
Multicast with caching (Mcache)
  • Server multicasts body of a video using
    • object channels: multicast the body of the video
    • patch channels: multicast parts of the video right after the prefix
  • Client initiates two parallel requests
    • the prefix from the cache
    • video body from the server
  • Server:calculates schedule and inform client which channel and when to join
conclusion
Conclusion

Various schemes for scalable video distribution

  • Concern only hot and popular video
  • Emulate the native Video on Demand service while requiring much less ressources at the server
  • Server Push vs. Client Pull models
  • Zero latency vs. Non-zero latency schemes
slide21

patched

Prefix(cached)

Body(server)

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