1. Distributing Layered Encoded Video through Caches Jussi Kangasharju Keith W.Ross Felix Hartanto Martin Reisslein

2. Outline Introduction – Layered Video Model of Layered Video Streaming with Proxy Optimal Caching – Utility Definations Evaluation of Heuristics Conclusion

3. Introduction Many videos are transported by the Internet recently. Highly heterogeneous,56Kbps~10Mbps. Layered encoded video is appropriate for the internet. How to efficienty distribute stored layered video from servers to end users? Which videos and which layers should be cached?

4. Layered Video Base Layer Coding Enhancement Layer Coding Video inBase Layer Bitstream _ Enhancement Layer 1 Bitstream _ Enhancement Layer Coding Enhancement Layer 2 Bitstream

5. Model of Layered Video Streaming with Proxy All media object are stored on the origin servers. Popular streams are cached in proxy servers. Client direct their request to the appropriate proxy server. Goal:cache object layers so as to maximize the revenue accrued from the streaming service

6. Model of Layered Video Streaming with Proxy Video object m, m=1,…,M Layer l,l=1,…,L j-quality stream, a stream consisting of layers 1,2,…,j p(j,m), the probability that a request is for the j- quality stream of the object m λ, request rate(requests/sec) B c (j,m), blocking probability of the request R(j,m), the revenue accrued from providing a j- quality stream of object m

7. Model of Layered Video Streaming with Proxy The expected blocking probability of a client’s request The long run rate at which these requests are granted and serviced The long run total rate of revenue of the streaming service

8. Optimal Caching Utility Heuristics:assign each of the ML object layers a cache utility The object layer are cached in decreasing order A particular enhancement layer can only be decoded if all lower quality layers are available Once a layer of an object has been skipped, all other layers of this object are ignored

9. Optimal Caching Utility Definations

10. Evaluation of Heuristics 1000movies Cache size 12~256Gbytes(0.9%~41. 7%) Link capacity 10~150Mbps(1~15%)

11. Evaluation of Heuristics the revenue density utility heuristic has the best performance

12. Evaluation of Heuristics If we have a shortage of both resources, we should first increase the cache before increasing the link capacity

13. Evaluation of Heuristics Movies become more equally popular requires increase in link capacity and cache size to keep the revenue at the same level

14. Conclusion Three different heuristics for determining which layers of which videos to cache. The best performance is obtained with the revenue density heuristic.