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Transmitting Scalable Video over a DiffServ network

Transmitting Scalable Video over a DiffServ network . EE368C Project Presentation Sangeun Han, Athina Markopoulou 3/6/01. Project Proposal. Problem: Video transmission over the heterogeneous Internet Facts:

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Transmitting Scalable Video over a DiffServ network

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  1. Transmitting Scalable Video over a DiffServ network EE368C Project Presentation Sangeun Han, Athina Markopoulou 3/6/01

  2. Project Proposal • Problem: • Video transmission over the heterogeneous Internet • Facts: • Scalability: different parts of a video stream contribute unequally to the quality. • DiffServ Networks can provide service differentiation, based on the marking of packets. • Proposal • Limit the effect of loss when it happens. Prioritize information according to importance and drop packets accordingly.

  3. conditioning classification AF11 Specifics • What type of scalability? H.263+, SNR • Which DiffServ class? AF (priority dropping) EI EP EP EP EL BL I P P P

  4. Simulation scenario Main stream: Foreman (10fps) 136Kbps, BL+EL, 2min 10-20 Interfering Streams BL+EL~=136Kbps random parts of 6 different streams Single AF queue, 2 levels, 100KB 1.5Mbps H.263+ Encoder + Layering RTP Packet. for H.263 (*) Depackt. Decoding+ [Error Conceal.] (**) Marker Loss info (*) Mode A: at frame level, Total header= IP(20)+UDP(8)+RTP(12)+H.263(4)=44B Original Stream (**) Freezing previous frame

  5. Objective of the Project • Show the benefit from using Priority Dropping for Scalable Video • MUX gain • Graceful Quality Degradation • Handle short term congestion • Configuration • AF queue: • buffer management, thresholds, other parameters • Layering parameters • base layer, temporal dependence • Recommendation • To Feedback or to Drop?

  6. MUX gain Layered+PD Nonlayered

  7. FGS + data loss Graceful degradation with loss NL, no loss Layered+loss Non Layered + loss

  8. Rate Congestion EL BL time R Reaction with no delay D=0 time D D Reaction with Delay D>0 time Short Term Congestion • The source may react to congestion by adapting its transmission rate...

  9. Reaction time vs.congestion duration • Simple example: • 10 streams + 5 more in [55sec,65sec] • 10 streams react by dropping their EL in [55+D, 65+D]

  10. Heavier congestion • Heavy + non adaptive interfering traffic: • 10 streams + 10 more in [55sec,65sec] • 10 streams react by dropping their EL in [55+D, 65+D]

  11. Rate Congestion R(t) EL BL time Priority dropping vs Feedback • Feedback • is limited by delay • saves network resources • requires coordination • Priority Dropping • is like reaction in D=0, by appropriate rate decrease • may handle non adaptive sources

  12. BL - low drop precedence EL - high drop precedence Drop prob High drop Low drop 1 0 Buffer occupancy L_min L_max H_min,max Configuration of AF queue • Choices: • Thresholds for the different priorities • Buffer management: RED or DropTail? • Observations: • Not sensitive to choice of thresholds • RED inappropriate: do not use Avg Qsize, set Lmin=Lmax • Differentiation: (I) different thresholds (II) Occupancy

  13. RED worse than DropTail For all loads…. and …for all thresholds

  14. Threshold for EL(HP) • By assigning the buffer thresholds • we control the Queue Occupancy for BL, EL Threshold_HDP = 56 Threshold_HDP = 16

  15. Threshold for EL(LP) • …this way we distribute the loss among BL and EL • ….and thus the quality • Insensitive to: • RED, DropTail • BL choice • [more sensitive to load]

  16. QP(BL)=12, 1:1, (BL=64kbps:EL=74kbps) QP(BL)=15, 1:2, (BL=50kbps:EL=86kbps) QP(BL)=30, 1:4, (BL=27kbps:EL=110kbps) Same target rate: BL+EL~=136kbps Effect of BL (I): on quality degradation

  17. QP(BL)=12, 1:1, (BL=64kbps:EL=74kbps) QP(BL)=15, 1:2, (BL=50kbps:EL=86kbps) QP(BL)=30, 1:4, (BL=27kbps:EL=110kbps) Same target rate: BL+EL~=136kbps Effect of BL (II): on thresholds

  18. Transmission of Scalable Video • Use feedback + adaptation at the source to match the transmission rate with the bottleneck bandwidth, to save network resources along the path • Use Priority Dropping to handle short term congestion Quality Feedback BL2 BL1 PD Rate loss

  19. Future work • Improvements needed • realistic feedback + adaptation • >2 layers • finish FGS • New experiments needed • Delay aspect: • Loss at the playback buffer • Entire streams having different delay requirements • Multiple hops • Single wireless hop (802.11 + QoS) • Video + Data • Larger Bandwidths • Other types of scalability: FGS, Temporal, Spatial, DP

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