Layered Coding & Congestion Adaptation in a Multicast Scalable Video Delivery System

1. Layered Coding & Congestion Adaptation in a Multicast Scalable Video Delivery System Yuming Jiang Q2S, NTNU Q2S Friday Colloquium, February 6, 2004

2. Outline • Introdution • The System • Layered Multicast • Embedded Zerotree Wavelet (EZW) Coding • Color-Resolution Layered Coding • Tri-zerotrees (TRI-ZTR) Coding • Color-Resolution Layering • Layer Prioritization & Automatic Congestion Adaptation • Layered Multicast & Layer Prioritization • Congestion Adaptation at Client • Congestion Handling at Router • Summary • Some Issues for Discussion

3. Real-Time Video Delivery System

4. Layered Multicast

5. Embedded Zerotree Wavelet Coding

6. Tri-Zerotree Coding (1)

7. Tri-Zerotree Coding (2)

8. Color-Resolution Layering (1) Gray component Color components V Y U BL EL1 EL3 EL4 EL2 EL5

9. Color-Resolution Layering (2)

10. Layer Multicast Priority BL Group 1 High EL1 Group 2 Low EL2 Group 3 Low EL3 Group 4 Low EL4 Group 5 Low EL5 Group 6 Low Resolution Gray Color 1/16 BL +EL3 1/4 BL+EL1 +EL3+EL4 Full BL+EL1+EL2 +EL3+EL4+EL5 Layered Multicast & Layer Prioritization

11. Congestion Adaptation at Client • Manual Congestion Adaptation • When congestion happens, the client notices the degradation of video quality and manually changes/decreases its subscriptions to layers. • Automatic Congestion Adaptation • The client automatically increase or decrease its subscriptions to layers based on the following layer-add and layer-drop policies: • Increase subscription if the probed loss rate is less than T_add; • Decrease subcription if the probed loss rate is larger than T_drop. T_add=max_add-δ_add x l T_drop=max_drop-δ_drop x l l (=0, ..., 5): the number of ELs subscribed max_add: maximum loss rate beyond which no new layer is added max_drop: maximum loss rate beyond which all layers should be dropped δ_add/ δ_drop: separation between T_add/T_drop of adjacent layers • T_add and T_drop values are affected by the setting of the congestion handling scheme implemented at network router.

12. Packet drop prob. 1.0 Max_p_el Max_p_bl Buffer occupancy For Enhancement Layers For Base Layer Congestion Adaptation at Router • Adopt DiffServ to provide isolation from best effort traffic. • Implement Assured Forwarding to support multiple drop precedences. • Use multi-level RED (random early detection) for buffer management when congestion happens. Two-level RED

13. Sample Client Displays Full size QCIF color 1/4 size QCIF monochrome

14. Summary • Introduced a Multicast Scalable Video Delivery System • Presented a Color-Resolution Layered Coding Scheme • Briefed an Automatic Congestion Adaptation Approach

15. Issues for Further Research • How to packetize video stream and what is its effect on received video quality in the case of packet loss? • How to prioritize layers? • How many priority levels are needed and how many levels are sufficient? • What is the effect of each layer loss and what is the tolerable loss rate? • How to design a network scheme to satisfy the loss requirement and what is the effect of its parameter setting? • How to design a congestion adaptation policy at client and what is its effect on the network and final perceived video quality? • What is the tolerable delay for each priority layer? • How to design network schemes to satisfy the delay requirement? • What are the corresponding requirements for other applications such as telephony and conferencing? • What are the corresponding requirements for other coding schemes, particularly those with inter-frame coding? etc.

16. Perceived content Rendering Decoing Content Consumer Received content Buffering. Reordering Adapting Delay guarant. Loss guarant. Network Network content End-To-End Content Delivery Packetizing Layering Mapping Layer diff. Cons. diff. Compressed content Coding Storing Content Provider Raw content 2004 IEEE Workshop on Coordinated QoS in Distributed Systems (http://www.sp.edu.sg/icon2004/) Coordinated Quality of Service for End-to-End Content Delivery