Rate Adaptations

1. Rate Adaptations

2. You are Here Encoder Decoder Middlebox Receiver Sender Network

3. Sender’s Algorithm open UDP socket foreach video frame chop into packets add RTP header send to network

4. Sender’s Algorithm open UDP socket foreach video frame chop into packets add RTP header send to network wait for 1/fps seconds

5. Sender’s Algorithm open UDP socket foreach video frame chop into packets foreach packet add RTP header send to network wait for size/bps seconds

6. Rules • Transmission rate should match encoding rate • Transmission should not be too bursty

7. Just send at a fix rate or “I hope the network can handle it” approach” Two Approaches

8. Effects on TCP: Simulation From Sisalem, Emanuel and Schulzrinne paper on “Direct Adjustment Algorithm”

9. Effects on TCP

10. Demo Effects of UDP on TCP without congestion control

11. Just send at a fix rate or “I hope the network can handle it” approach” Adapt transmission/encoding rate to network condition Two Approaches

12. How to Adapt? if network condition is bad reduce rate else if network condition is so-so do nothing else if network condition is good increase rate

13. How to .. • Know “network condition is bad”? • increase/decrease rate?

14. Adapting Output Rate if network condition is bad else if network condition is so-so do nothing else if network condition is good

15. Question: What should  and  be?

16. Observation 1 • Should never change your rate more than an equivalent TCP

17. Observation 2 •  and  should depend on network conditions and current rate.

18. Goal: Fair Share of Bottleneck • let r r : current rate b : bottleneck bandwidth S : current share

19. S vs   S 1

20. Value of  (Assuming one receiver)

21. Limit of  • M : packet size •  : round trip time • T : period between evaluation of 

22. Limit of  M : packet size  : round trip time T : period between evaluation of 

23. loss rate vs   1 1 loss rate

24. Value of m where is the loss rate k is a constant (Assuming one receiver)

26. What is Needed?

27. Estimating b : Packet Pair

28. Estimating b : Packet Pair

29. Estimating b : Packet Pair

30. Evaluation

31. More TCP-Friendly Rate Control

32. TCP-Equation Window size behavior in TCP/IP with constant loss probability T. Ott, J. Kemperman, and M. Mathis June 1997, HPCS 1997

33. TCP-Equation Equation-Based Congestion Control for Unicast Applications Sally Floyd, Mark Handley, Jitendra Padhye, and Joerg Widmer.August 2000. SIGCOMM 2000

34. Another Transport Protocol • Datagram Congestion Control Protocol (DCCP) • Implements congestion control but not reliability

35. Rules • Transmission rate should match encoding rate • Transmission should not be too bursty

36. Rate Control Given a rate, how to encode the video with the given rate?

37. Reduce Frame Rate • Live Video • Stored Video

38. Reduce Frame Resolution • Live Video • Stored Video

39. Increase Quantization • Live Video • Stored Video

40. Drop AC components • Live Video • Stored Video

41. Trouble with Stored Video • Reducing rate requires partial decoding and re-encoding • Solution: Layered Video

42. Layered Video or “Scalable Video”

43. Layered Video Layer 1 Layer 2 Layer 3

44. Layering Scheme • Temporal Layering

45. Layering Scheme • Spatial Layering

46. Layering Scheme • DCT Layering 30 8 2 30 8 2 0 30 -6 -1 -6 -1 0 0 1 1 0 0 0 0 0 0 0

47. Layering Scheme • Fine Granularity Scalability (FGS) 1 1 0 0 0 0 0 0 1 1 1 0 0 0 1 0 1 0 0 1 0 1 0 1 1 0 0 0 0 1 0 0

48. Rate Adaptation • To increase rate, send more layers • To decrease rate, drop some layers

49. MS Windows Streaming Media

50. Intelligent Streaming • Multiple-Bit-Rate Encoding • Intelligent Bandwidth Control • bit rate selection • thinning • Intelligent Image Processing