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Motivation
                                                  Background
                                                  Impact of FEC on Scalable Video
                                                  Adaptive FEC Control
                                                  Evaluation
                                                  Conclusion




                      Impact of FEC Overhead on
                       Scalable Video Streaming

                   Seong-ryong Kang and Dmitri Loguinov

                            Department of Computer Science
                                Texas A&M University
                              College Station, TX 77843


                                    June 14, 2005



S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        1/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Outline


         Motivation
         Background
         Impact of FEC on Scalable Video
         Adaptive FEC Control
         Evaluation
         Conclusion




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        2/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Outline


         Motivation
         Background
         Impact of FEC on Scalable Video
         Adaptive FEC Control
         Evaluation
         Conclusion




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        3/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Motivation of this work




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        4/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Motivation of this work




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        4/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Motivation of this work

        Internet streaming is an important part of the Internet




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        4/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Motivation of this work

        Internet streaming is an important part of the Internet
        Streaming applications usually require special mechanisms
        that can overcome packet loss without utilizing retransmission




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        4/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Motivation of this work

        Internet streaming is an important part of the Internet
        Streaming applications usually require special mechanisms
        that can overcome packet loss without utilizing retransmission
        FEC is often considered for recovering lost data segments




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        4/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Motivation of this work

        Internet streaming is an important part of the Internet
        Streaming applications usually require special mechanisms
        that can overcome packet loss without utilizing retransmission
        FEC is often considered for recovering lost data segments
        However, studies reported conflicting results on the benefits of
        FEC




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        4/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Motivation of this work

        Internet streaming is an important part of the Internet
        Streaming applications usually require special mechanisms
        that can overcome packet loss without utilizing retransmission
        FEC is often considered for recovering lost data segments
        However, studies reported conflicting results on the benefits of
        FEC

        Our work aims to:
               address this uncertainty and
               provide additional insight into understanding how FEC
               overhead affects the performance of scalable video streaming


  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        4/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Outline


         Motivation
         Background
         Impact of FEC on Scalable Video
         Adaptive FEC Control
         Evaluation
         Conclusion




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        5/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Background




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        6/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Background

  FEC
        FEC schemes require application servers to send extra
        information along with the original data
        Media independent FEC
               Based on (N, k) block codes (such as parity or Reed-Solomon
               codes), where N is the size of an FEC block and k is the
               number of FEC packets in the block
        All data packets are recovered if the number of lost packets in
        a block is no more than k
        If more than k packets are lost, none of them can be
        recovered by the receiver

  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        6/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Background




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        7/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Background


  FGS
        Streaming profile of the ISO/IEC MPEG-4 standard
        Method of compressing residual video signal into a single
        enhancement layer
        Allows application servers to scale the enhancement layer to
        match variable network capacity during streaming
        The enhancement layer is typically coded at some fixed bitrate
        and can be rescaled to any desired bitrate



  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        7/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Background




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        8/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Background




  Because of dependency in
  the enhancement layer,
  higher sections of FGS
  cannot be used in decoding
  the frame without the
  presence of lower sections



  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        8/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Background




  Because of dependency in                                    loss
  the enhancement layer,
  higher sections of FGS
  cannot be used in decoding                                  loss
  the frame without the                                                                       useful
  presence of lower sections                                                                 packets



  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        8/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Outline


         Motivation
         Background
         Impact of FEC on Scalable Video
         Adaptive FEC Control
         Evaluation
         Conclusion




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        9/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Analysis of video streaming




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        10/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Analysis of video streaming

        We investigate the performance of FEC-based streaming
        considering Markov and renewal patterns of packet loss




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        10/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Analysis of video streaming

        We investigate the performance of FEC-based streaming
        considering Markov and renewal patterns of packet loss
               We use MPEG-4 FGS as an example and only examine the
               enhancement layer




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        10/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Analysis of video streaming

        We investigate the performance of FEC-based streaming
        considering Markov and renewal patterns of packet loss
               We use MPEG-4 FGS as an example and only examine the
               enhancement layer
        Note that many studies show that Internet packet loss can be
        captured by Markov models
               Alternating ON/OFF renewal process can model more general
               distribution of packet loss and allows heavy-tailed burst lengths




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        10/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Analysis of video streaming

        We investigate the performance of FEC-based streaming
        considering Markov and renewal patterns of packet loss
               We use MPEG-4 FGS as an example and only examine the
               enhancement layer
        Note that many studies show that Internet packet loss can be
        captured by Markov models
               Alternating ON/OFF renewal process can model more general
               distribution of packet loss and allows heavy-tailed burst lengths

        In what follows, we derive the expected amount of useful data
        E[Zj ] recovered from each frame
               Zj is the number of consecutively received packets in a frame j


  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        10/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Analysis of video streaming




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        11/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Analysis of video streaming
        Assume that long-term network packet loss is given by p




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        11/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Analysis of video streaming
        Assume that long-term network packet loss is given by p
        Loss process can be modeled by a two-state Markov chain:




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        11/30
Motivation
                                                      Background
                                                      Impact of FEC on Scalable Video
                                                      Adaptive FEC Control
                                                      Evaluation
                                                      Conclusion


Analysis of video streaming
        Assume that long-term network packet loss is given by p
        Loss process can be modeled by a two-state Markov chain:
                                     α

                            1—α         0                          1         1—β

                                                     β




  S. Kang and D. Loguinov     Impact of FEC Overhead on Scalable Video Streaming        11/30
Motivation
                                                      Background
                                                      Impact of FEC on Scalable Video
                                                      Adaptive FEC Control
                                                      Evaluation
                                                      Conclusion


Analysis of video streaming
        Assume that long-term network packet loss is given by p
        Loss process can be modeled by a two-state Markov chain:
                                     α

                            1—α         0                          1         1—β

                                                     β
               α and β are transition probabilities
               In the stationary state, probabilities π0 and π1 to find the
               process in each of its two states are given by:
                                              β              α
                                     π0 =        , π1 = p =     .                               (1)
                                             α+β            α+β

  S. Kang and D. Loguinov     Impact of FEC Overhead on Scalable Video Streaming        11/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Analysis of video streaming




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        12/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Analysis of video streaming
        To derive E[Zj ], we define:




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        12/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Analysis of video streaming
        To derive E[Zj ], we define:
               L to be the number of packets lost in an FEC block
               ¯
               Q = E[Zj |L > k] to be the expected number of useful video
               packets recovered from the front of an FEC block when L > k




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        12/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Analysis of video streaming
        To derive E[Zj ], we define:
               L to be the number of packets lost in an FEC block
               ¯
               Q = E[Zj |L > k] to be the expected number of useful video
               packets recovered from the front of an FEC block when L > k
        Then, we have the following result:




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        12/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Analysis of video streaming
        To derive E[Zj ], we define:
               L to be the number of packets lost in an FEC block
               ¯
               Q = E[Zj |L > k] to be the expected number of useful video
               packets recovered from the front of an FEC block when L > k
        Then, we have the following result:
  Lemma 1
  Assuming a two-state Markov packet loss and L > k, the expected
  number of useful video packets recovered per frame is:

                  ¯                  1−p
                  Q = E[Zj |L > k] =     1 − (1 − α)H ,                                       (2)
                                      α
  where H = N − k is the number of video packets in an FEC block

  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        12/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Analysis of video streaming




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        13/30
Motivation
                                                        Background
                                                        Impact of FEC on Scalable Video
                                                        Adaptive FEC Control
                                                        Evaluation
                                                        Conclusion


Analysis of video streaming

  Theorem 1
  Assuming two-state Markov packet loss with average loss
  probability p, the expected number of useful packets recovered per
  FEC block of size N is:
                            k
       E[Zj ] =                   P (N, i)H                                                           (3)
                            i=0
                                    N
                                                            1−p
                            +             P (N, i)              1 − (1 − α)H                      ,
                                                             α
                                  i=k+1
  where P (N, i) is the probability of losing exactly i packets out of
  N transmitted packets.

  S. Kang and D. Loguinov       Impact of FEC Overhead on Scalable Video Streaming        13/30
Motivation
                                                     Background
                                                     Impact of FEC on Scalable Video
                                                     Adaptive FEC Control
                                                     Evaluation
                                                     Conclusion


Simulation results




   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        14/30
Motivation
                                                     Background
                                                     Impact of FEC on Scalable Video
                                                     Adaptive FEC Control
                                                     Evaluation
                                                     Conclusion


Simulation results
         Define ψ to be the fraction of FEC packets in a block




   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        14/30
Motivation
                                                     Background
                                                     Impact of FEC on Scalable Video
                                                     Adaptive FEC Control
                                                     Evaluation
                                                     Conclusion


Simulation results
         Define ψ to be the fraction of FEC packets in a block
         To verify the model, we simulate Markov loss process with
         two different values of ψ




   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        14/30
Motivation
                                                                                   Background
                                                                                   Impact of FEC on Scalable Video
                                                                                   Adaptive FEC Control
                                                                                   Evaluation
                                                                                   Conclusion


Simulation results
         Define ψ to be the fraction of FEC packets in a block
         To verify the model, we simulate Markov loss process with
         two different values of ψ

                                    2500                                                            350

                                    2000                                                            300
             Decoding rate (kb/s)




                                                                             Decoding rate (kb/s)
                                                                                                    250
                                    1500
                                                                                                    200
                                    1000
                                                                                                    150
                                                             Model                                                        Model
                                    500                      Simulation                                                   Simulation
                                                                                                    100

                                           500   1000 1500 2000 2500 3000                                 500   1000 1500 2000 2500 3000
                                                  Sending rate S (kb/s)                                          Sending rate S (kb/s)


                                             (a) ψ = 1.1p                                                   (b) ψ = 0.9p
                                    ˜
     Figure: Expected decoding rate R (p = 0.1, α = 0.08, and β = 0.72)
   S. Kang and D. Loguinov                            Impact of FEC Overhead on Scalable Video Streaming                               14/30
Motivation
                                                     Background
                                                     Impact of FEC on Scalable Video
                                                     Adaptive FEC Control
                                                     Evaluation
                                                     Conclusion


Simulation results




   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        15/30
Motivation
                                                     Background
                                                     Impact of FEC on Scalable Video
                                                     Adaptive FEC Control
                                                     Evaluation
                                                     Conclusion


Simulation results


         Note that the behavior of expected decoding rate changes for
         different ψ




   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        15/30
Motivation
                                                     Background
                                                     Impact of FEC on Scalable Video
                                                     Adaptive FEC Control
                                                     Evaluation
                                                     Conclusion


Simulation results


         Note that the behavior of expected decoding rate changes for
         different ψ
         The amount of overhead in FEC-based streaming plays a
         significant role in determining video quality




   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        15/30
Motivation
                                                     Background
                                                     Impact of FEC on Scalable Video
                                                     Adaptive FEC Control
                                                     Evaluation
                                                     Conclusion


Simulation results


         Note that the behavior of expected decoding rate changes for
         different ψ
         The amount of overhead in FEC-based streaming plays a
         significant role in determining video quality
         Next, we derive the utility of received video and examine how
         FEC overhead affects the quality of video




   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        15/30
Motivation
                                                     Background
                                                     Impact of FEC on Scalable Video
                                                     Adaptive FEC Control
                                                     Evaluation
                                                     Conclusion


Simulation results


         Note that the behavior of expected decoding rate changes for
         different ψ
         The amount of overhead in FEC-based streaming plays a
         significant role in determining video quality
         Next, we derive the utility of received video and examine how
         FEC overhead affects the quality of video
         Define the utility U as the fraction of received data that is
         useful for decoding



   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        15/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Analysis of video streaming

  Theorem 2
  Assuming Bernoulli packet loss in an FEC block of size N , average
  loss probability p, and FEC overhead rate ψ = ηp, (0 < ψ < 1),
  the utility of received video for each FEC block converges to the
  following as H → ∞:
                                
                                0
                                        0<η<1
                      lim U = 0.5        η=1         ,             (4)
                     H→∞         1−ψ
                                         1 < η < 1/p
                                
                                  1−p

  where η is constant.


  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        16/30
Motivation
                                                     Background
                                                     Impact of FEC on Scalable Video
                                                     Adaptive FEC Control
                                                     Evaluation
                                                     Conclusion


Simulation results




   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        17/30
Motivation
                                                     Background
                                                     Impact of FEC on Scalable Video
                                                     Adaptive FEC Control
                                                     Evaluation
                                                     Conclusion


Simulation results

         Simulation results under Bernoulli loss




   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        17/30
Motivation
                                                                    Background
                                                                    Impact of FEC on Scalable Video
                                                                    Adaptive FEC Control
                                                                    Evaluation
                                                                    Conclusion


Simulation results

         Simulation results under Bernoulli loss

                                          1

                                         0.8                η=1.1


                                         0.6        η=1.0
                               Utility




                                         0.4
                                                                         Model
                                                     η=0.9               Simulation
                                         0.2

                                          0
                                               0   1000   2000 3000 4000       5000
                                                           Frame size H




   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming                       17/30
Motivation
                                                                    Background
                                                                    Impact of FEC on Scalable Video
                                                                    Adaptive FEC Control
                                                                    Evaluation
                                                                    Conclusion


Simulation results

         Simulation results under Bernoulli loss

                                          1

                                         0.8                η=1.1


                                         0.6        η=1.0
                               Utility




                                         0.4
                                                                         Model
                                                     η=0.9               Simulation
                                         0.2

                                          0
                                               0   1000   2000 3000 4000       5000
                                                           Frame size H



  Note that U indeed converges to 0, 0.5 or (1 − ψ)/(1 − p)
  depending on the value of ψ as the streaming rate becomes large

   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming                       17/30
Motivation
                                                     Background
                                                     Impact of FEC on Scalable Video
                                                     Adaptive FEC Control
                                                     Evaluation
                                                     Conclusion


Simulation results




   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        18/30
Motivation
                                                     Background
                                                     Impact of FEC on Scalable Video
                                                     Adaptive FEC Control
                                                     Evaluation
                                                     Conclusion


Simulation results
         Note that the asymptotic behavior of U in Theorem 2 holds
         for Markov and renewal patterns of packet loss




   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        18/30
Motivation
                                                                        Background
                                                                        Impact of FEC on Scalable Video
                                                                        Adaptive FEC Control
                                                                        Evaluation
                                                                        Conclusion


Simulation results
         Note that the asymptotic behavior of U in Theorem 2 holds
         for Markov and renewal patterns of packet loss
                         1                                                     1

                                       h=1.2
                        0.8                                                   0.8

                        0.6    h=1.0                                          0.6
              Utility




                                                                    Utility
                        0.4                                                   0.4                           h = 1.2
                               h=0.8
                                                       Model                                                h = 1.0
                                                       Simulation                                           h = 0.8
                        0.2                                                   0.2

                         0                                                     0
                                 500           1000         1500                       500          1000      1500
                                        Frame size H                                         Frame size H


                              (a) Markov loss                                       (b) Renewal loss




   S. Kang and D. Loguinov                Impact of FEC Overhead on Scalable Video Streaming                   18/30
Motivation
                                                                        Background
                                                                        Impact of FEC on Scalable Video
                                                                        Adaptive FEC Control
                                                                        Evaluation
                                                                        Conclusion


Simulation results
         Note that the asymptotic behavior of U in Theorem 2 holds
         for Markov and renewal patterns of packet loss
                         1                                                     1

                                       h=1.2
                        0.8                                                   0.8

                        0.6    h=1.0                                          0.6
              Utility




                                                                    Utility
                        0.4                                                   0.4                           h = 1.2
                               h=0.8
                                                       Model                                                h = 1.0
                                                       Simulation                                           h = 0.8
                        0.2                                                   0.2

                         0                                                     0
                                 500           1000         1500                       500          1000      1500
                                        Frame size H                                         Frame size H


                              (a) Markov loss                                       (b) Renewal loss

  Again, U exhibits percolation and converges to 0, 0.5 or
  (1 − ψ)/(1 − p) depending on ψ

   S. Kang and D. Loguinov                Impact of FEC Overhead on Scalable Video Streaming                   18/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Discussion




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        19/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Discussion


  Effectiveness of FEC
  depends on how the server
  uses redundant packets
  based on packet-loss
  dynamics
  Using fixed amount of
  overhead may cause
  significant quality
  degradation when packet
  loss fluctuates


  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        19/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Discussion


                                                     Simulation results of U for
  Effectiveness of FEC
                                                     different packet loss p under
  depends on how the server
                                                     improper amount of FEC overhead
  uses redundant packets
  based on packet-loss
                                                                    1
  dynamics
                                                                   0.8
  Using fixed amount of                                             0.6



                                                         Utility
  overhead may cause                                               0.4
                                                                                         ideal amount
                                                                                         improper amount
  significant quality
                                                                   0.2
  degradation when packet
                                                                    0
  loss fluctuates                                                         0   0.1   0.2     0.3
                                                                                   Packet loss
                                                                                                   0.4     0.5




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming                   19/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Outline


         Motivation
         Background
         Impact of FEC on Scalable Video
         Adaptive FEC Control
         Evaluation
         Conclusion




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        20/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Adaptive FEC control




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        21/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Adaptive FEC control


  Needs for adaptive control
      In a practical network environment, packet loss changes
      dynamically, depending on
               cross-traffic
               link quality
               routing updates, etc
        The amount of FEC needs to be adjusted according to
        changing packet loss to maintain high end-user utility




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        21/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Adaptive FEC control




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        22/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Adaptive FEC control

        For adaptive FEC rate control, we use a simple proportional
        controller:




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        22/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Adaptive FEC control

        For adaptive FEC rate control, we use a simple proportional
        controller:

            ψi (n) = ψi (n − Di ) + τ (ηpi (n − Di ) − ψi (n − Di )) ,                        (5)

        where index i represents flow number, pi (n) is the measured
        average packet loss in the FGS layer for flow i during interval
        n, τ is the controller’s gain parameter, Di is the round-trip
        delay for flow i.




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        22/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Adaptive FEC control

        For adaptive FEC rate control, we use a simple proportional
        controller:

            ψi (n) = ψi (n − Di ) + τ (ηpi (n − Di ) − ψi (n − Di )) ,                        (5)

        where index i represents flow number, pi (n) is the measured
        average packet loss in the FGS layer for flow i during interval
        n, τ is the controller’s gain parameter, Di is the round-trip
        delay for flow i.

  Lemma 2
  Controller (5) is stable if and only if 0 < τ < 2.

  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        22/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Outline


         Motivation
         Background
         Impact of FEC on Scalable Video
         Adaptive FEC Control
         Evaluation
         Conclusion




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        23/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Packet loss pattern




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        24/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Packet loss pattern
        We simulate a streaming session with a hypothetical packet
        loss pattern




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        24/30
Motivation
                                                                           Background
                                                                           Impact of FEC on Scalable Video
                                                                           Adaptive FEC Control
                                                                           Evaluation
                                                                           Conclusion


Packet loss pattern
        We simulate a streaming session with a hypothetical packet
        loss pattern
                          0.5                                                          0.8


                          0.4




                                                              Transition probability
                                                                                       0.6
            Packet loss




                          0.3                                                                                           β
                                                                                       0.4                              α
                          0.2

                                                                                       0.2
                          0.1

                           0                                                            0
                                0   10          20      30                                   5   10    15     20   25       30
                                    Time (seconds)                                                Time (seconds)


                            (a) Packet loss pattern           (b) Transition probability α,β




  S. Kang and D. Loguinov              Impact of FEC Overhead on Scalable Video Streaming                               24/30
Motivation
                                                     Background
                                                     Impact of FEC on Scalable Video
                                                     Adaptive FEC Control
                                                     Evaluation
                                                     Conclusion


Achieved utility




   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        25/30
Motivation
                                                     Background
                                                     Impact of FEC on Scalable Video
                                                     Adaptive FEC Control
                                                     Evaluation
                                                     Conclusion


Achieved utility


         We investigate adaptive FEC overhead controller (5) with the
         behavior of achieved utility




   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        25/30
Motivation
                                                     Background
                                                     Impact of FEC on Scalable Video
                                                     Adaptive FEC Control
                                                     Evaluation
                                                     Conclusion


Achieved utility


         We investigate adaptive FEC overhead controller (5) with the
         behavior of achieved utility
                To illustrate the adaptivity of the controller, we use target
                utility UT = 0.8




   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        25/30
Motivation
                                                     Background
                                                     Impact of FEC on Scalable Video
                                                     Adaptive FEC Control
                                                     Evaluation
                                                     Conclusion


Achieved utility


         We investigate adaptive FEC overhead controller (5) with the
         behavior of achieved utility
                To illustrate the adaptivity of the controller, we use target
                utility UT = 0.8
         For comparison, we apply two different scenarios that use
         fixed amount of overhead




   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        25/30
Motivation
                                                     Background
                                                     Impact of FEC on Scalable Video
                                                     Adaptive FEC Control
                                                     Evaluation
                                                     Conclusion


Achieved utility


         We investigate adaptive FEC overhead controller (5) with the
         behavior of achieved utility
                To illustrate the adaptivity of the controller, we use target
                utility UT = 0.8
         For comparison, we apply two different scenarios that use
         fixed amount of overhead
                The fixed-overhead amount is driven by the lower and upper
                bounds on packet loss p
                                      ˜




   S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        25/30
Motivation
                                                  Background
                                                  Impact of FEC on Scalable Video
                                                  Adaptive FEC Control
                                                  Evaluation
                                                  Conclusion



      The evolution of achieved utility U




S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        26/30
Motivation
                                                             Background
                                                             Impact of FEC on Scalable Video
                                                             Adaptive FEC Control
                                                             Evaluation
                                                             Conclusion



      The evolution of achieved utility U
                                    adaptive                                        adaptive
                     1              fixed                            1              fixed

                    0.8                                             0.8
          Utility




                                                          Utility
                    0.6                                             0.6

                    0.4                                             0.4

                    0.2                                             0.2

                     0                                               0
                          0     10          20      30                    0     10          20     30
                                Time (seconds)                                  Time (seconds)


                              (a) p = 0.1
                                  ˜                                           (b) p = 0.4
                                                                                  ˜




S. Kang and D. Loguinov            Impact of FEC Overhead on Scalable Video Streaming            26/30
Motivation
                                                             Background
                                                             Impact of FEC on Scalable Video
                                                             Adaptive FEC Control
                                                             Evaluation
                                                             Conclusion



      The evolution of achieved utility U
                                    adaptive                                        adaptive
                     1              fixed                            1              fixed

                    0.8                                             0.8
          Utility




                                                          Utility
                    0.6                                             0.6

                    0.4                                             0.4

                    0.2                                             0.2

                     0                                               0
                          0     10          20      30                    0     10          20     30
                                Time (seconds)                                  Time (seconds)


                              (a) p = 0.1
                                  ˜                                           (b) p = 0.4
                                                                                  ˜

      Our adaptive controller maintains the target utility UT very
      well along the entire streaming session
      However, fixed-overhead schemes cannot maintain high utility
      as packet loss varies

S. Kang and D. Loguinov            Impact of FEC Overhead on Scalable Video Streaming            26/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


PSNR quality




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        27/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


PSNR quality

        PSNR of CIF Foreman reconstructed with different FEC
        overhead control




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        27/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


PSNR quality

        PSNR of CIF Foreman reconstructed with different FEC
        overhead control
        M1 and M2 use fixed amount of overhead driven by p = 0.1
                                                        ˜
        and p = 0.4, respectively
            ˜




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        27/30
Motivation
                                                                      Background
                                                                      Impact of FEC on Scalable Video
                                                                      Adaptive FEC Control
                                                                      Evaluation
                                                                      Conclusion


PSNR quality

                 PSNR of CIF Foreman reconstructed with different FEC
                 overhead control
                 M1 and M2 use fixed amount of overhead driven by p = 0.1
                                                                 ˜
                 and p = 0.4, respectively
                     ˜


                45


                40
    PSNR (dB)




                35

                         adaptive
                30       M1
                         M2
                25
                     0   20      40    60       80    100
                               Frame number


  S. Kang and D. Loguinov                     Impact of FEC Overhead on Scalable Video Streaming        27/30
Motivation
                                                                      Background
                                                                      Impact of FEC on Scalable Video
                                                                      Adaptive FEC Control
                                                                      Evaluation
                                                                      Conclusion


PSNR quality

                 PSNR of CIF Foreman reconstructed with different FEC
                 overhead control
                 M1 and M2 use fixed amount of overhead driven by p = 0.1
                                                                 ˜
                 and p = 0.4, respectively
                     ˜

                                                                             The adaptive method offers
                45                                                           as much as 2.5 dB higher
                40
                                                                             PSNR than M2 for the first
    PSNR (dB)




                                                                             60 frames
                35

                         adaptive
                                                                             Also, outperforms M1 by
                30       M1
                         M2                                                  almost 10 dB for the last 40
                25
                     0   20      40    60       80    100                    frames
                               Frame number


  S. Kang and D. Loguinov                     Impact of FEC Overhead on Scalable Video Streaming        27/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Outline


         Motivation
         Background
         Impact of FEC on Scalable Video
         Adaptive FEC Control
         Evaluation
         Conclusion




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        28/30
Motivation
                                                    Background
                                                    Impact of FEC on Scalable Video
                                                    Adaptive FEC Control
                                                    Evaluation
                                                    Conclusion


Conclusion



        FEC has conflicting effects on video quality depending on the
        amount of overhead used
        Adaptive FEC overhead control can provide a high quality of
        video to end-users
        Proper control of FEC overhead can significantly improve the
        utility of received video over lossy channels




  S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        29/30
Motivation
                                                  Background
                                                  Impact of FEC on Scalable Video
                                                  Adaptive FEC Control
                                                  Evaluation
                                                  Conclusion




                                     Thank you!

                                  Any questions?




S. Kang and D. Loguinov   Impact of FEC Overhead on Scalable Video Streaming        30/30

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Impact of FEC Overhead on Scalable Video Streaming

  • 1. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Impact of FEC Overhead on Scalable Video Streaming Seong-ryong Kang and Dmitri Loguinov Department of Computer Science Texas A&M University College Station, TX 77843 June 14, 2005 S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 1/30
  • 2. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Outline Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 2/30
  • 3. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Outline Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 3/30
  • 4. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Motivation of this work S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 4/30
  • 5. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Motivation of this work S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 4/30
  • 6. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Motivation of this work Internet streaming is an important part of the Internet S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 4/30
  • 7. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Motivation of this work Internet streaming is an important part of the Internet Streaming applications usually require special mechanisms that can overcome packet loss without utilizing retransmission S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 4/30
  • 8. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Motivation of this work Internet streaming is an important part of the Internet Streaming applications usually require special mechanisms that can overcome packet loss without utilizing retransmission FEC is often considered for recovering lost data segments S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 4/30
  • 9. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Motivation of this work Internet streaming is an important part of the Internet Streaming applications usually require special mechanisms that can overcome packet loss without utilizing retransmission FEC is often considered for recovering lost data segments However, studies reported conflicting results on the benefits of FEC S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 4/30
  • 10. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Motivation of this work Internet streaming is an important part of the Internet Streaming applications usually require special mechanisms that can overcome packet loss without utilizing retransmission FEC is often considered for recovering lost data segments However, studies reported conflicting results on the benefits of FEC Our work aims to: address this uncertainty and provide additional insight into understanding how FEC overhead affects the performance of scalable video streaming S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 4/30
  • 11. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Outline Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 5/30
  • 12. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Background S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 6/30
  • 13. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Background FEC FEC schemes require application servers to send extra information along with the original data Media independent FEC Based on (N, k) block codes (such as parity or Reed-Solomon codes), where N is the size of an FEC block and k is the number of FEC packets in the block All data packets are recovered if the number of lost packets in a block is no more than k If more than k packets are lost, none of them can be recovered by the receiver S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 6/30
  • 14. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Background S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 7/30
  • 15. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Background FGS Streaming profile of the ISO/IEC MPEG-4 standard Method of compressing residual video signal into a single enhancement layer Allows application servers to scale the enhancement layer to match variable network capacity during streaming The enhancement layer is typically coded at some fixed bitrate and can be rescaled to any desired bitrate S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 7/30
  • 16. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Background S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 8/30
  • 17. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Background Because of dependency in the enhancement layer, higher sections of FGS cannot be used in decoding the frame without the presence of lower sections S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 8/30
  • 18. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Background Because of dependency in loss the enhancement layer, higher sections of FGS cannot be used in decoding loss the frame without the useful presence of lower sections packets S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 8/30
  • 19. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Outline Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 9/30
  • 20. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Analysis of video streaming S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 10/30
  • 21. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Analysis of video streaming We investigate the performance of FEC-based streaming considering Markov and renewal patterns of packet loss S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 10/30
  • 22. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Analysis of video streaming We investigate the performance of FEC-based streaming considering Markov and renewal patterns of packet loss We use MPEG-4 FGS as an example and only examine the enhancement layer S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 10/30
  • 23. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Analysis of video streaming We investigate the performance of FEC-based streaming considering Markov and renewal patterns of packet loss We use MPEG-4 FGS as an example and only examine the enhancement layer Note that many studies show that Internet packet loss can be captured by Markov models Alternating ON/OFF renewal process can model more general distribution of packet loss and allows heavy-tailed burst lengths S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 10/30
  • 24. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Analysis of video streaming We investigate the performance of FEC-based streaming considering Markov and renewal patterns of packet loss We use MPEG-4 FGS as an example and only examine the enhancement layer Note that many studies show that Internet packet loss can be captured by Markov models Alternating ON/OFF renewal process can model more general distribution of packet loss and allows heavy-tailed burst lengths In what follows, we derive the expected amount of useful data E[Zj ] recovered from each frame Zj is the number of consecutively received packets in a frame j S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 10/30
  • 25. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Analysis of video streaming S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 11/30
  • 26. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Analysis of video streaming Assume that long-term network packet loss is given by p S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 11/30
  • 27. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Analysis of video streaming Assume that long-term network packet loss is given by p Loss process can be modeled by a two-state Markov chain: S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 11/30
  • 28. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Analysis of video streaming Assume that long-term network packet loss is given by p Loss process can be modeled by a two-state Markov chain: α 1—α 0 1 1—β β S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 11/30
  • 29. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Analysis of video streaming Assume that long-term network packet loss is given by p Loss process can be modeled by a two-state Markov chain: α 1—α 0 1 1—β β α and β are transition probabilities In the stationary state, probabilities π0 and π1 to find the process in each of its two states are given by: β α π0 = , π1 = p = . (1) α+β α+β S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 11/30
  • 30. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Analysis of video streaming S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 12/30
  • 31. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Analysis of video streaming To derive E[Zj ], we define: S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 12/30
  • 32. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Analysis of video streaming To derive E[Zj ], we define: L to be the number of packets lost in an FEC block ¯ Q = E[Zj |L > k] to be the expected number of useful video packets recovered from the front of an FEC block when L > k S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 12/30
  • 33. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Analysis of video streaming To derive E[Zj ], we define: L to be the number of packets lost in an FEC block ¯ Q = E[Zj |L > k] to be the expected number of useful video packets recovered from the front of an FEC block when L > k Then, we have the following result: S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 12/30
  • 34. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Analysis of video streaming To derive E[Zj ], we define: L to be the number of packets lost in an FEC block ¯ Q = E[Zj |L > k] to be the expected number of useful video packets recovered from the front of an FEC block when L > k Then, we have the following result: Lemma 1 Assuming a two-state Markov packet loss and L > k, the expected number of useful video packets recovered per frame is: ¯ 1−p Q = E[Zj |L > k] = 1 − (1 − α)H , (2) α where H = N − k is the number of video packets in an FEC block S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 12/30
  • 35. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Analysis of video streaming S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 13/30
  • 36. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Analysis of video streaming Theorem 1 Assuming two-state Markov packet loss with average loss probability p, the expected number of useful packets recovered per FEC block of size N is: k E[Zj ] = P (N, i)H (3) i=0 N 1−p + P (N, i) 1 − (1 − α)H , α i=k+1 where P (N, i) is the probability of losing exactly i packets out of N transmitted packets. S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 13/30
  • 37. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Simulation results S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 14/30
  • 38. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Simulation results Define ψ to be the fraction of FEC packets in a block S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 14/30
  • 39. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Simulation results Define ψ to be the fraction of FEC packets in a block To verify the model, we simulate Markov loss process with two different values of ψ S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 14/30
  • 40. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Simulation results Define ψ to be the fraction of FEC packets in a block To verify the model, we simulate Markov loss process with two different values of ψ 2500 350 2000 300 Decoding rate (kb/s) Decoding rate (kb/s) 250 1500 200 1000 150 Model Model 500 Simulation Simulation 100 500 1000 1500 2000 2500 3000 500 1000 1500 2000 2500 3000 Sending rate S (kb/s) Sending rate S (kb/s) (a) ψ = 1.1p (b) ψ = 0.9p ˜ Figure: Expected decoding rate R (p = 0.1, α = 0.08, and β = 0.72) S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 14/30
  • 41. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Simulation results S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 15/30
  • 42. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Simulation results Note that the behavior of expected decoding rate changes for different ψ S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 15/30
  • 43. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Simulation results Note that the behavior of expected decoding rate changes for different ψ The amount of overhead in FEC-based streaming plays a significant role in determining video quality S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 15/30
  • 44. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Simulation results Note that the behavior of expected decoding rate changes for different ψ The amount of overhead in FEC-based streaming plays a significant role in determining video quality Next, we derive the utility of received video and examine how FEC overhead affects the quality of video S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 15/30
  • 45. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Simulation results Note that the behavior of expected decoding rate changes for different ψ The amount of overhead in FEC-based streaming plays a significant role in determining video quality Next, we derive the utility of received video and examine how FEC overhead affects the quality of video Define the utility U as the fraction of received data that is useful for decoding S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 15/30
  • 46. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Analysis of video streaming Theorem 2 Assuming Bernoulli packet loss in an FEC block of size N , average loss probability p, and FEC overhead rate ψ = ηp, (0 < ψ < 1), the utility of received video for each FEC block converges to the following as H → ∞:  0  0<η<1 lim U = 0.5 η=1 , (4) H→∞  1−ψ 1 < η < 1/p  1−p where η is constant. S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 16/30
  • 47. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Simulation results S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 17/30
  • 48. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Simulation results Simulation results under Bernoulli loss S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 17/30
  • 49. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Simulation results Simulation results under Bernoulli loss 1 0.8 η=1.1 0.6 η=1.0 Utility 0.4 Model η=0.9 Simulation 0.2 0 0 1000 2000 3000 4000 5000 Frame size H S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 17/30
  • 50. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Simulation results Simulation results under Bernoulli loss 1 0.8 η=1.1 0.6 η=1.0 Utility 0.4 Model η=0.9 Simulation 0.2 0 0 1000 2000 3000 4000 5000 Frame size H Note that U indeed converges to 0, 0.5 or (1 − ψ)/(1 − p) depending on the value of ψ as the streaming rate becomes large S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 17/30
  • 51. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Simulation results S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 18/30
  • 52. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Simulation results Note that the asymptotic behavior of U in Theorem 2 holds for Markov and renewal patterns of packet loss S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 18/30
  • 53. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Simulation results Note that the asymptotic behavior of U in Theorem 2 holds for Markov and renewal patterns of packet loss 1 1 h=1.2 0.8 0.8 0.6 h=1.0 0.6 Utility Utility 0.4 0.4 h = 1.2 h=0.8 Model h = 1.0 Simulation h = 0.8 0.2 0.2 0 0 500 1000 1500 500 1000 1500 Frame size H Frame size H (a) Markov loss (b) Renewal loss S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 18/30
  • 54. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Simulation results Note that the asymptotic behavior of U in Theorem 2 holds for Markov and renewal patterns of packet loss 1 1 h=1.2 0.8 0.8 0.6 h=1.0 0.6 Utility Utility 0.4 0.4 h = 1.2 h=0.8 Model h = 1.0 Simulation h = 0.8 0.2 0.2 0 0 500 1000 1500 500 1000 1500 Frame size H Frame size H (a) Markov loss (b) Renewal loss Again, U exhibits percolation and converges to 0, 0.5 or (1 − ψ)/(1 − p) depending on ψ S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 18/30
  • 55. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Discussion S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 19/30
  • 56. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Discussion Effectiveness of FEC depends on how the server uses redundant packets based on packet-loss dynamics Using fixed amount of overhead may cause significant quality degradation when packet loss fluctuates S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 19/30
  • 57. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Discussion Simulation results of U for Effectiveness of FEC different packet loss p under depends on how the server improper amount of FEC overhead uses redundant packets based on packet-loss 1 dynamics 0.8 Using fixed amount of 0.6 Utility overhead may cause 0.4 ideal amount improper amount significant quality 0.2 degradation when packet 0 loss fluctuates 0 0.1 0.2 0.3 Packet loss 0.4 0.5 S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 19/30
  • 58. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Outline Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 20/30
  • 59. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Adaptive FEC control S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 21/30
  • 60. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Adaptive FEC control Needs for adaptive control In a practical network environment, packet loss changes dynamically, depending on cross-traffic link quality routing updates, etc The amount of FEC needs to be adjusted according to changing packet loss to maintain high end-user utility S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 21/30
  • 61. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Adaptive FEC control S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 22/30
  • 62. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Adaptive FEC control For adaptive FEC rate control, we use a simple proportional controller: S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 22/30
  • 63. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Adaptive FEC control For adaptive FEC rate control, we use a simple proportional controller: ψi (n) = ψi (n − Di ) + τ (ηpi (n − Di ) − ψi (n − Di )) , (5) where index i represents flow number, pi (n) is the measured average packet loss in the FGS layer for flow i during interval n, τ is the controller’s gain parameter, Di is the round-trip delay for flow i. S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 22/30
  • 64. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Adaptive FEC control For adaptive FEC rate control, we use a simple proportional controller: ψi (n) = ψi (n − Di ) + τ (ηpi (n − Di ) − ψi (n − Di )) , (5) where index i represents flow number, pi (n) is the measured average packet loss in the FGS layer for flow i during interval n, τ is the controller’s gain parameter, Di is the round-trip delay for flow i. Lemma 2 Controller (5) is stable if and only if 0 < τ < 2. S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 22/30
  • 65. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Outline Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 23/30
  • 66. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Packet loss pattern S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 24/30
  • 67. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Packet loss pattern We simulate a streaming session with a hypothetical packet loss pattern S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 24/30
  • 68. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Packet loss pattern We simulate a streaming session with a hypothetical packet loss pattern 0.5 0.8 0.4 Transition probability 0.6 Packet loss 0.3 β 0.4 α 0.2 0.2 0.1 0 0 0 10 20 30 5 10 15 20 25 30 Time (seconds) Time (seconds) (a) Packet loss pattern (b) Transition probability α,β S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 24/30
  • 69. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Achieved utility S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 25/30
  • 70. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Achieved utility We investigate adaptive FEC overhead controller (5) with the behavior of achieved utility S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 25/30
  • 71. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Achieved utility We investigate adaptive FEC overhead controller (5) with the behavior of achieved utility To illustrate the adaptivity of the controller, we use target utility UT = 0.8 S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 25/30
  • 72. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Achieved utility We investigate adaptive FEC overhead controller (5) with the behavior of achieved utility To illustrate the adaptivity of the controller, we use target utility UT = 0.8 For comparison, we apply two different scenarios that use fixed amount of overhead S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 25/30
  • 73. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Achieved utility We investigate adaptive FEC overhead controller (5) with the behavior of achieved utility To illustrate the adaptivity of the controller, we use target utility UT = 0.8 For comparison, we apply two different scenarios that use fixed amount of overhead The fixed-overhead amount is driven by the lower and upper bounds on packet loss p ˜ S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 25/30
  • 74. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion The evolution of achieved utility U S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 26/30
  • 75. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion The evolution of achieved utility U adaptive adaptive 1 fixed 1 fixed 0.8 0.8 Utility Utility 0.6 0.6 0.4 0.4 0.2 0.2 0 0 0 10 20 30 0 10 20 30 Time (seconds) Time (seconds) (a) p = 0.1 ˜ (b) p = 0.4 ˜ S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 26/30
  • 76. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion The evolution of achieved utility U adaptive adaptive 1 fixed 1 fixed 0.8 0.8 Utility Utility 0.6 0.6 0.4 0.4 0.2 0.2 0 0 0 10 20 30 0 10 20 30 Time (seconds) Time (seconds) (a) p = 0.1 ˜ (b) p = 0.4 ˜ Our adaptive controller maintains the target utility UT very well along the entire streaming session However, fixed-overhead schemes cannot maintain high utility as packet loss varies S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 26/30
  • 77. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion PSNR quality S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 27/30
  • 78. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion PSNR quality PSNR of CIF Foreman reconstructed with different FEC overhead control S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 27/30
  • 79. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion PSNR quality PSNR of CIF Foreman reconstructed with different FEC overhead control M1 and M2 use fixed amount of overhead driven by p = 0.1 ˜ and p = 0.4, respectively ˜ S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 27/30
  • 80. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion PSNR quality PSNR of CIF Foreman reconstructed with different FEC overhead control M1 and M2 use fixed amount of overhead driven by p = 0.1 ˜ and p = 0.4, respectively ˜ 45 40 PSNR (dB) 35 adaptive 30 M1 M2 25 0 20 40 60 80 100 Frame number S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 27/30
  • 81. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion PSNR quality PSNR of CIF Foreman reconstructed with different FEC overhead control M1 and M2 use fixed amount of overhead driven by p = 0.1 ˜ and p = 0.4, respectively ˜ The adaptive method offers 45 as much as 2.5 dB higher 40 PSNR than M2 for the first PSNR (dB) 60 frames 35 adaptive Also, outperforms M1 by 30 M1 M2 almost 10 dB for the last 40 25 0 20 40 60 80 100 frames Frame number S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 27/30
  • 82. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Outline Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 28/30
  • 83. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Conclusion FEC has conflicting effects on video quality depending on the amount of overhead used Adaptive FEC overhead control can provide a high quality of video to end-users Proper control of FEC overhead can significantly improve the utility of received video over lossy channels S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 29/30
  • 84. Motivation Background Impact of FEC on Scalable Video Adaptive FEC Control Evaluation Conclusion Thank you! Any questions? S. Kang and D. Loguinov Impact of FEC Overhead on Scalable Video Streaming 30/30