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Transmitting Scalable Video over a DiffServ network

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Title: Transmitting Scalable Video over a DiffServ network


1
Transmitting Scalable Video over a DiffServ
network
  • EE368C
  • Project Proposal
  • Sangeun Han, Athina Markopoulou
  • 1/30/01

2
References - Motivation
  • Scalable Video Coding Transmission
  • U.Horn B. Girod, Scalable video transmission
    for the Internet, Computer Networks and ISDN
    Systems, 1997.
  • M. van der Schaar H.Radha, A hybrid
    temporal-SNR FGS for the Internet video, IEEE
    Trans. on Circuits and Systems for Video
    Technology.
  • J.Kimura F.Tobagi, Perceived quality and
    bandwidth characterization of layered MPEG-2
    video encoding, SPIE 1999.
  • S.McCanne, N.Vetterli V.Jacobson, Low
    complexity video coding for receiver -driven
    layered multicast, JSAC 1997.
  • Differentiated Services
  • http//www.ietf.org/html-charters/diffserv-charter
    .html
  • RFC 2475, RFC 2597
  • Software
  • NS simulator http//www.isi.edu/nsnam/ns/
  • ITU-T Recommendation H.263 (Annex O)

3
Overview
  • Scalable video coding
  • MPEG-2, H.263 SNR, Spatial, Temporal,
  • MPEG-4, H.26L FGS
  • Transmission over the network
  • In general
  • DiffServ
  • Our scenario
  • Simulation setup
  • Issues

4
Scalable Video Coding
5
Fine-Granularity Scalability
  • Notes
  • Problems limited scalability, error propagation
  • Standards MPEG-4, H.26L
  • FGS advantages transmission over networks w/ BW
    variation, error resilience

6
Transmission Loss
  • Small loss translates into drastic quality
    degradation (loss of important data temporal
    dependence)
  • Transmission over the Internet is lossy
  • Need to use the available bandwidth to send the
    most important data

7
Solutions
  • Feedback adapt transmission rate to variations
  • Disadvantages complexity, granularity of BW
    adjustments, delay in feedback, overhead,
    inappropriate for multicast or high variability
  • Receiver Driven Layered Multicast
  • Problems overhead, delay, granularity of BW
  • Smoothing Admission control
  • Idea limit stream and load variability.
  • Disadvantages complexity, overhead, delay, model
  • Loss happens control its effect by dealing with
    it intelligently
  • Unequal error protection
  • Priority dropping

Use the available bandwidth for the most
important data
8
Priority Dropping
  • Loss is inevitable. Limit its effect when it
    happens. Prioritize information according to
    importance (contribution to quality)
  • Drop packets according to their priority

Advantages simple sender, handles heterogeneous
receivers short term congestion
9
QoS architectures for the Internet
  • Best effort no guarantees
  • Integrated Services (IntServ) Per-flow
    guarantees
  • Differentiated Services (DiffServ) Per aggregate
    guarantees

10
Example of a DiffServ node
  • Packet are marked (DSCP)
  • Each packet is treated according to this marking

AF11
11
AF class
  • IETF DiffServ WG in RFC 2597 defines 4 Assured
    Forwarding (AF) classes
  • Each AFx class marking with AFx1, AFx2, AFx3
  • Minimum BW guaranteed for the AFx aggregate.
  • 3 dropping priorities (1,2,3).

12
Scalable video in DiffServ
  • Use a particular AF Class for Video
  • Mark different layers with different AF dropping
    priorities
  • Define mechanisms to be used for the Video AF
    Class
  • Give rationale on how to create layers to work
    together with AF

13
Approach
  • Simulation trying scenarios

Playback buffer
H.263 Encoder Layering
RTP Packet.
Decoding Error Conceal.
Depackt.
DiffServ Network
Marker
(Packet Loss)
Layered video
Layered video
RTP Transport
14
Issues
  • Purpose show benefit of combining layering and
    priority dropping
  • Network point of view Provide recommendations
    for DiffServ standardization
  • How many priorities are really needed?
  • How to configure AF class?
  • How to choose the layering parameters?
  • Coding point of view Explore benefit of
    layering/FGS
  • under Internet loss scenarios
  • E.g., Tradeoff between motion smoothness and
    quality of pictures under buffer loss, or mix
    with bursty data
  • Significance of fine granularity for real
    scenarios

15
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