1. Wavelet-Based VBR Video Traffic Smoothing Dejian Ye, J. Cam Barker, Zixiang Xiong, and Wenwu Zhu IEEE Trans. Multimedia, Aug. 2004

2. Outline • VBR video transmission • Smoothing algorithms • MVBA (minimum variance) • MCBA (minimum changes) • PCRTT (piecewise constant-rate) • WTS (wavelet-based traffic smoothing) • Smoothing at multiple resolution • Low computational complexity • Performance evaluation

3. Typical video distribution scenario

4. VBR: single traffic flow

5. VBR: aggregated traffic flow From server to client: link 3 link 2 link 1

6. Buffer constraints

7. MVBA (minimum variance bandwidth allocation) U L

8. MCBA (minimum changes bandwidth allocation) U L

9. PCRTT (piecewise constant-rate transmission and transport) • Divide the video stream into segments to create a transmission schedule. • Each segment corresponds to one rate in the transmission schedule. (set the transmission rate to the average frame size for each segment) • Raise the transmission schedule to avoid client buffer underflow. • Force a rate change after every segment.

10. PCRTT L Seg 1 Seg 2 Seg 3 Seg 4 Seg 5

11. WTS • PCRTT works well for both single and aggregated flows. • WTS is based on PCRTT. • Motivations: • Smooth aggregated flows. (?) • Client buffers can be heterogeneous. (difficult to schedule transmission)

12. Possible schedules in WTS

13. uj+2, 4k+3 uj+2, 4k+2 uj+1, 2k Binary tree Tmax Has enough buffer?

14. Multiple-flow clients and movies

15. #flow: #rate changes

16. #flow: rate variation

17. #flow: the min time between two adjacent rate changes

18. #flow: peak rate

19. Buffer size: #rate changes

20. Buffer size: rate variance

21. Buffer size: the min #frames between two adjacent rate changes

22. Buffer size: peak rate