1 / 92

Reminder

Reminder. Project Proposal Due Next Mon. Submit by Email. Problems with Internet. Limited Bandwidth Varying Bandwidth Delay Delay Jitter Packet Loss Heterogeneity :. Error Recovery. You Are Here. Encoder. Decoder. Middlebox. Receiver. Sender. Network. Overview.

derrickr
Download Presentation

Reminder

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Reminder Project Proposal Due Next Mon. Submit by Email

  2. Problems with Internet • Limited Bandwidth • Varying Bandwidth • Delay • Delay Jitter • Packet Loss • Heterogeneity : NUS.SOC.CS5248 OOI WEI TSANG

  3. Error Recovery

  4. You Are Here Encoder Decoder Middlebox Receiver Sender Network NUS.SOC.CS5248 OOI WEI TSANG

  5. Overview • Characteristics of the Internet • General techniques • Error recovery for audio • Effect of loss on MPEG • Error recovery for MPEG NUS.SOC.CS5248 OOI WEI TSANG

  6. Loss Characteristics of The Internet

  7. Characteristics of Internet • 60-70% of paths do not show any loss • Those with loss have an average of 4.5 – 6% packet loss [Paxson97] End-to-end Internet packet dynamics NUS.SOC.CS5248 OOI WEI TSANG

  8. Packet Loss Pattern 1000 30 NUS.SOC.CS5248 OOI WEI TSANG

  9. Characteristic of Internet • Bursts of loss are typically short (2-3 consecutively loss packets) • Long burst do occur • Burst may occur periodically NUS.SOC.CS5248 OOI WEI TSANG

  10. Wireless Link • Loss rate measured in my office 10 ~ 20% • up to 50% reported! NUS.SOC.CS5248 OOI WEI TSANG

  11. A Survey of Packet-Loss Recovery Techniques for Streaming Audio Perkins, Hodson and Hardman IEEE Network Magazine 1998

  12. Retransmission 1 2 3 4 3 1 2 4 3 NUS.SOC.CS5248 OOI WEI TSANG

  13. Redundant Data 1 2 2 3 3 4 4 5 1 2 2 3 3 4 5 NUS.SOC.CS5248 OOI WEI TSANG

  14. Error Concealment 1 2 3 4 1 2 4 NUS.SOC.CS5248 OOI WEI TSANG

  15. Pros and Cons • retransmission • redundant data • error concealment NUS.SOC.CS5248 OOI WEI TSANG

  16. Retransmission for audio

  17. Retransmission is Bad • Need scalable feedback • NACK consumes bandwidth • May need to retransmit frequently • Retransmission maybe useless NUS.SOC.CS5248 OOI WEI TSANG

  18. Retransmission is Good • Only retransmit when needed NUS.SOC.CS5248 OOI WEI TSANG

  19. Scalable Retransmission • On packet loss • T = random(0, RTT) • wait for T • multicast NACK • On receiving NACK from others • suppress own NACK NUS.SOC.CS5248 OOI WEI TSANG

  20. Retransmit when • group size is small • loss rate is low • large latency acceptable NUS.SOC.CS5248 OOI WEI TSANG

  21. Redundant Data for audio

  22. Parity FEC 1011001 XOR 1000010 0010010 0001001 NUS.SOC.CS5248 OOI WEI TSANG

  23. Parity FEC 1011001 1000010 0001001 0010010 NUS.SOC.CS5248 OOI WEI TSANG

  24. Parity FEC Ordering NUS.SOC.CS5248 OOI WEI TSANG

  25. Parity FEC Ordering NUS.SOC.CS5248 OOI WEI TSANG

  26. Parity FEC Ordering NUS.SOC.CS5248 OOI WEI TSANG

  27. Parity FEC Ordering NUS.SOC.CS5248 OOI WEI TSANG

  28. Parity FEC Ordering NUS.SOC.CS5248 OOI WEI TSANG

  29. Reed-Solomon Code • RS(n,k) RS NUS.SOC.CS5248 OOI WEI TSANG

  30. Reed-Solomon Code NUS.SOC.CS5248 OOI WEI TSANG

  31. Media Specific FEC 1 2 2 3 3 4 4 5 1 2 2 3 3 4 5 NUS.SOC.CS5248 OOI WEI TSANG

  32. Interleaving NUS.SOC.CS5248 OOI WEI TSANG

  33. Error Concealment

  34. Effect of Loss on Audio • Speech • Human ears can interpolate • Loss up to length of phoneme can still be tolerable NUS.SOC.CS5248 OOI WEI TSANG

  35. Insertion-based Repair • Splice • Silence Substitution • Noise Substitution • Repetition NUS.SOC.CS5248 OOI WEI TSANG

  36. Other Repair Methods • Interpolation • Regeneration NUS.SOC.CS5248 OOI WEI TSANG

  37. Colin’s Recommendations

  38. Non-Interactive Apps • Interleaving • FEC • Retransmission for unicast only NUS.SOC.CS5248 OOI WEI TSANG

  39. Interactive Applications • Media Specific FEC NUS.SOC.CS5248 OOI WEI TSANG

  40. Error Concealment • Repeat NUS.SOC.CS5248 OOI WEI TSANG

  41. Packet Loss Effects on MPEG Video Sent over the Public Internet Jill Boyce and Robert Gaglianello ACM Multimedia 1998

  42. Measurement-based Study • Need to understand the problem before proposing solution NUS.SOC.CS5248 OOI WEI TSANG

  43. NUS.SOC.CS5248 OOI WEI TSANG

  44. Data Gathering Method • From: NYC13 , Austin21, London18 • To: Holmdel, NJ NUS.SOC.CS5248 OOI WEI TSANG

  45. Data Gathering Method • Video: • Two 5-mins MPEG • 30 fps • 384 kbps and 1 Mbps • IBBPBBPBBPBBPBB • QSIF 176x112 and SIF 352x240 • One row per slice NUS.SOC.CS5248 OOI WEI TSANG

  46. Average Packet Loss NUS.SOC.CS5248 OOI WEI TSANG

  47. Packet Loss vs Time NUS.SOC.CS5248 OOI WEI TSANG

  48. How to Fill Packets • B 1 frame 1 packet • P 1 slice 1 packet • I 1 slice 1 packet NUS.SOC.CS5248 OOI WEI TSANG

  49. Packet Size Distributions NUS.SOC.CS5248 OOI WEI TSANG

  50. Packet Size vs Loss Rate NUS.SOC.CS5248 OOI WEI TSANG

More Related