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A Model for MPEG with Forward Error Correction (FEC) and TCP-Friendly Bandwidth

A Model for MPEG with Forward Error Correction (FEC) and TCP-Friendly Bandwidth. Huahui Wu, Mark Claypool & Robert Kinicki Computer Science Department Worcester Polytechnic Institute Worcester, MA, 01609 USA {flashine,claypool,rek}@cs.wpi.edu. Outline. Introduction Protocol Repair

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A Model for MPEG with Forward Error Correction (FEC) and TCP-Friendly Bandwidth

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  1. A Model for MPEG with Forward Error Correction (FEC) and TCP-Friendly Bandwidth Huahui Wu, Mark Claypool & Robert Kinicki Computer Science Department Worcester Polytechnic Institute Worcester, MA, 01609 USA {flashine,claypool,rek}@cs.wpi.edu

  2. Outline • Introduction • Protocol • Repair • Related Knowledge • Analytical Model • Analytical Experiments • Simulation Experiments • Summary 6/3/2003 NOSSDAV 2003 Monterey, California #2

  3. Transmission Protocol • TCP uses retransmission • No good for interactive application • UDP have no retransmission • It doesn’t respond to congestion • TCP-Friendly [FHPW00] [RHE99] • Well behavior protocol • Loss is still an important issue 6/3/2003 NOSSDAV 2003 Monterey, California #3

  4. Repair and Forward Error Correction • Packet loss degrades the quality • FEC adds redundancy and fixes loss • Increase congestion to video stream • Prior Approaches • Ad-hoc • Not TCP-Friendly • Our Approach: • Adjusting FEC with TCP-Friendly bandwidth constraint. 6/3/2003 NOSSDAV 2003 Monterey, California #4

  5. Outline • Introduction • Related Knowledge • MPEG • Forward Error Correction • TCP-Friendly • Analytical Model • Analytical Experiments • Simulation Experiments • Summary 6/3/2003 NOSSDAV 2003 Monterey, California #5

  6. MPEG • Three types of frames • I (Intra-coded): Coded independently • P (Predictive-coded): obtain prediction from preceding I or P frame • B (Bidirectional predictive-coded): obtain prediction from the preceding and succeeding I or P frames • Group of Picture (GOP) 6/3/2003 NOSSDAV 2003 Monterey, California #6

  7. Forward Error Correction (FEC) • Packet loss degrades video quality. • FEC adds redundancy to recover from losses. • With an MPEG frame made up of K ordinary packets, FEC adds N-K redundant packets to frame. • If K or more of the N packets are received, the original frame can be successfully reconstructed. • The successful frame transmission probability is (2) 6/3/2003 NOSSDAV 2003 Monterey, California #7

  8. TCP-Friendly Flows • Unresponsive flows get unfair share of network bandwidth and AQM techniques will punish them. • Streaming flows need to be TCP-Friendly. • A TCP-Friendly flow’s bandwidth is no more than a conformant TCP flow running under comparable network conditions. (1) [PFTK98] 6/3/2003 NOSSDAV 2003 Monterey, California #8

  9. Outline • Introduction • Related Knowledge • Analytical Model • Successful Frame Transmission Probability • GOP Rate • Playable Frame Rate • Analytical Experiments • Simulation Experiments • Summary 6/3/2003 NOSSDAV 2003 Monterey, California #9

  10. Successful Frame Transmission Probability (3) 6/3/2003 NOSSDAV 2003 Monterey, California #10

  11. GOP Rate • TCP Friendly Rate • GOP Rate (GOP per second) 6/3/2003 NOSSDAV 2003 Monterey, California #11

  12. Playable Frame Rate Model (1 of 2) • Playable Frame Rate of I, P and B frames (4) 6/3/2003 NOSSDAV 2003 Monterey, California #12

  13. Playable Frame Rate Model (2 of 2) (5) • Given values of loss rate and frame size, the total playable frame rate can be estimated with the FEC and GOP pattern. • The best playable frame rate can be obtained by searching the FEC and GOP space. 6/3/2003 NOSSDAV 2003 Monterey, California #13

  14. Outline • Introduction • Related Knowledge • Analytical Model • Analytical Experiments • Methodology • Improvement on Playable Frame Rate • The Behaviors of FEC • Simulation Experiments • Summary 6/3/2003 NOSSDAV 2003 Monterey, California #14

  15. Methodology • Given a p, compute TCP-Friendly rate T. • With a specific GOP and FEC pattern, the playable frame rate R can be computed. • Search for the maximum rate Rm with all possible GOP and FEC pattern. • Investigate the improvement from adjusting FEC, and the FEC behavior. 6/3/2003 NOSSDAV 2003 Monterey, California #15

  16. Improvement of Playable Frame Rate RTT: 50ms s: 1KB p(%):0.5, 1, 2, 3, 4, … 10 SI: 25 packets SP: 8 packets SB: 3 packets [KSH95] GOP: IBBPBBPBBPBBPBB 6/3/2003 NOSSDAV 2003 Monterey, California #16

  17. Adjusted FEC pattern Y-axis: Number of packets, X-axis: Loss percentage 6/3/2003 NOSSDAV 2003 Monterey, California #17

  18. AFEC’s Advantage • Successful frame transmission Probability a. Non-FEC b. Adjusting FEC 6/3/2003 NOSSDAV 2003 Monterey, California #18

  19. Fixed FECs vs. Adjusted FEC • Fixed FECs vs. Adjusted FEC • Small: (1,1,0); Medium: (4,2,0); Large FEC: (8,4,1) 6/3/2003 NOSSDAV 2003 Monterey, California #19

  20. Outline • Introduction • Related Knowledge • Analytical Model • Analytical Experiments • Simulation Experiments • Simulation of Dependent Packet Loss • Simulation of Variable Round Trip Time • Summary 6/3/2003 NOSSDAV 2003 Monterey, California #20

  21. Simulation of Dependent Packet Loss • Losses are often dependent • Dependent loss reduce the effect of FEC • Cause a lower playable frame rate 6/3/2003 NOSSDAV 2003 Monterey, California #21

  22. Simulation of Variable Round Trip Time a. Distribution of RTT [CCZ03] b. Effect of Variable RTT 6/3/2003 NOSSDAV 2003 Monterey, California #22

  23. Outline • Introduction • Related Knowledge • Analytical Model • Analytical Experiments • Simulation Experiments • Summary • Contribution • Ongoing Work 6/3/2003 NOSSDAV 2003 Monterey, California #23

  24. Contribution • Built a model to estimate the playable frame rate for TCP-Friendly MPEG Streaming. • Used the model to study adjusting FEC and GOP behavior • Adjusting FEC provides large benefit. • 10 to 50 times improvement in playable frame rate with moderate to high loss probability. • Adjusting GOP provides little benefit. • More details are in the paper. 6/3/2003 NOSSDAV 2003 Monterey, California #24

  25. Ongoing Work • Model verification with realistic network • TCP-Friendly Video Streaming with other repair techniques. • Adjusting FEC combined with Media Scaling • Build into NS-2 Simulator • Implement it in real network 6/3/2003 NOSSDAV 2003 Monterey, California #25

  26. A Model for MPEG with Forward Error Correction (FEC) and TCP-Friendly Bandwidth Huahui Wu, Mark Claypool & Robert Kinicki Computer Science Department Worcester Polytechnic Institute Worcester, MA, 01609 USA {flashine,claypool,rek}@cs.wpi.edu

  27. Benefits from Adjusting FEC and/or GOP RTT: 50ms s: 1KB p(%):0.5, 1, 2, 3, 4, … 10 SI: 25 packets SP: 8 packets SB: 3 packets 6/3/2003 NOSSDAV 2003 Monterey, California #27

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