Sergei N. Kozlov, s.n.kozlov@tue.nl - PowerPoint PPT Presentation

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Sergei N. Kozlov, s.n.kozlov@tue.nl

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Streaming MPEG video over wireless link QoS in Digital In-home Networks PROGRESS project EES.5653 Agenda I-frame delay (summary on the approach) Progress since May ... – PowerPoint PPT presentation

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Title: Sergei N. Kozlov, s.n.kozlov@tue.nl


1
Streaming MPEG video over wireless link
  • QoS in Digital In-home Networks
  • PROGRESS project EES.5653

2
Agenda
  • I-frame delay (summary on the approach)
  • Progress since May 2004
  • Future plans
  • Demo

3
Video over wireless link
  • Typical scenario video transmission from a
    set-top box to the (mutiple) screens

Between 5 and 13 seconds a microwave oven is on
?t50ms
  • Wireless link
  • Low and highly variable throughput

4
Sender/receiver communication (RTP-based)
video source
video sink
Packets get lost here
sender buffer
receiver buffer
MAC retransmission mechanism
wireless interface (sender)
wireless inerface (receiver)
5
MPEG encoding
  • GOP (group-of-pictures)
  • Frame types I, P, B
  • Typical GOP structure and dependences

I BBPBBPBB(I)
6
Importance of I and P frames
  • Missing of I/P frames causes video artefacts
  • A complete stream only missing B frames has
  • no artefacts

In worst case you only get 8.3fps from originally
25fps
7
Cumulative weight of B-frames
  • An example of a 5Mbps stream (LOTR)
  • B-frames make up more than 50 of the whole
    bitrate

8
Link layer approach
Sender
MAC-retransmissions
Application/ encoder
Selectively drop frames here
video stream
IP packets
OS network stack
scheduler buffer
9
I-frame delay (IFD)
Stream generated by application
Transmitting under low and variable throughput
some frames take longer time
Frames displayed at receiver NN 1, 4, 5, 8 are
skipped
10
Pros and cons of link layer approach
  • We only need to modify sending part
  • it will work with any terminals supporting RTP
    reception and equiped with a general MPEG decoder
  • due to RTP (UDP-based), it can be used for
    broadcasting
  • It is very reactive against fast network
    fluctuations
  • Requires access to wireless interface
  • should be implemented at every sending device

11
Deployment of IFD
  • ASL, SC (Ewout Brandsma, Eric Persoon)
  • CE Connected Planet project (Tom Suters,
    Daniel Meirsman)
  • SLx00 products (Streamium)
  • CES at Las Vegas in June 2005 (with CE)
  • CRE in June 2005 (with ASL)

12
Progress since May 2004
  • A publication submitted to WoWMoM 2005
  • A demo set-up created
  • a number of successful demonstrations given
  • Deployment of IFD into real projects started (SC
    CE)
  • Future work made concrete (coming slides)
  • Yesterday IFD proved to work with a Linksys AP
  • IFD and wired wireless network
  • streaming to wireless CE devices (such as
    HotMan-2)

new
13
Further work (I) Evaluation of IFD models,
simulations and optimizations
  • Simulator (based on ns2)
  • variations of network topologies
  • variations of algorithms/buffer sizes for IFD
  • variations of video stream (GOP pattern
    variations, bit-rates, coding standards etc)

Optimal settings are the simulation goal
14
Future work (II) IFD above transport layer
  • If...
  • we dont have direct access to the wireless
    interface
  • we dont want to modify it
  • we want to use it with both wired/wireless
    networks
  • we want it over a reliable transport protocol
  • ... Then we would like to look at the tranport
    layer
  • implement the same idea in the application layer
    above TCP (master-student working on that)

15
Future work (III) IFD SNR scalability
(together with Dmitry)
  • The goal is to handle even higher variations in
    the link bandwidth
  • KISS project at NatLab is implementing it

16
Welcome to the demo!(given after the meeting)
  • Questions?
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