transmitting scalable video over a diffserv network
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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: - PowerPoint PPT PresentationTRANSCRIPT
1Sangeun Han, Athina Markopoulou
Transmitting Scalable Video over a DiffServ network
EE368C Project Presentation
Sangeun Han, Athina Markopoulou3/6/01
2Sangeun Han, Athina Markopoulou
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.
3Sangeun Han, Athina Markopoulou
Specifics• What type of scalability? H.263+, SNR
• Which DiffServ class? AF (priority dropping)
EF
AF1
AF2
AF3
AF4
BE
w2
w3
w4
w5
w6
buf fe rm a nagem ent
packe tsc heduling
high s t r ic t p r io rity
conditioning
classification
AF11
I P P P
EI EP EP EPEL
BL
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Simulation scenario
(*) Mode A: at frame level,Total header= IP(20)+UDP(8)+RTP(12)+H.263(4)=44B
(**) Freezing previous frame
H.263+Encoder
+Layering
RTPPacket.
for H.263(*)
Decoding+[Error
Conceal.] (**)Depackt.Marker
Single AF queue,2 levels, 100KB
Main stream: Foreman (10fps) 136Kbps, BL+EL, 2min
10-20 Interfering StreamsBL+EL~=136Kbpsrandom parts of 6 different streams
1.5Mbps
Loss info
Original Stream
5Sangeun Han, Athina Markopoulou
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?
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MUX gain
Nonlayered
Layered+PD
7Sangeun Han, Athina Markopoulou
Graceful degradation with loss
Layered+loss
Non Layered + loss
NL, no lossFGS
+ data loss
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Short Term Congestion• The source may react to congestion by adapting its transmission
rate...
Congestion
time
Rate
BLEL
D Dtime
time
Reaction with no delay D=0
Reaction with Delay D>0
R
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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]
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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]
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Priority dropping vs Feedback
• Priority Dropping – is like reaction in D=0, by appropriate rate decrease– may handle non adaptive sources
Congestion
time
Rate
BLEL
R(t)
• Feedback • is limited by delay• saves network resources• requires coordination
12Sangeun Han, Athina Markopoulou
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
Low dropDropprob High drop
Buffer occupancy
1
0
BL - low drop precedence EL - high drop precedence
L_min L_max H_min,max
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RED worse than DropTailFor all loads….
…for all thresholds
and
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Threshold for EL(HP)
• By assigning the buffer thresholds – we control the Queue
Occupancy for BL, EL
Threshold_HDP = 56 Threshold_HDP = 16
15Sangeun Han, Athina Markopoulou
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]
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Effect of BL (I): on quality degradation
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
17Sangeun Han, Athina Markopoulou
Effect of BL (II): on thresholds
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
18Sangeun Han, Athina Markopoulou
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
Rate
PD
loss
Feedback
BL1
BL2
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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