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

2. Project Proposal Problem: Facts: Proposal
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. Specifics What type of scalability? H.263+, SNR
Which DiffServ class? AF (priority dropping) EI EP EP EL EP BL I P P P
conditioning
classification
AF11

4. Simulation scenario Single AF queue, 2 levels, 100KB 1.5Mbps
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. Graceful degradation with loss
FGS
+ data loss
NL, no loss
Layered+loss
Non Layered + loss

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

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. Priority dropping vs 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
Congestion
time
Rate BL EL
R(t)

12. Configuration of AF queue
Low drop
Drop
prob
High drop
Buffer occupancy 1
BL - low drop precedence
EL - high drop precedence
L_min
L_max
H_min,max
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. 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

17. 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

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 New experiments 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 ( QoS)
Video + Data
Larger Bandwidths
Other types of scalability: FGS, Temporal, Spatial, DP