An evaluation of piece picking algorithms for layered content in bittorrent-based peer-to-peer systems
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An evaluation of piece picking algorithms for layered content in bittorrent-based peer-to-peer systems

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An evaluation of piece picking algorithms for layered content in bittorrent-based peer-to-peer systems An evaluation of piece picking algorithms for layered content in bittorrent-based peer-to-peer systems Presentation Transcript

  • An Evaluation of Piece-Picking Algorithms for LayeredContent in Bittorrent-based Peer-To-Peer Systems
    ICME 2011
    Special Session on Hot Topics in Multimedia Delivery
    Michael Eberhard
    1
    Piece-Picking Algorithm Evaluation
    Michael Eberhard
    Hermann Hellwagner
    Christian Timmerer
    AAU Klagenfurt
    TiborSzkaliczki Laszlo Szobonya
    MTA SZTAKI
  • Overview
    Introduction to PiecePicking
    AlgorithmforLayeredPiecePicking
    Evaluation Results
    Single/Multi LayerComparison
    Michael Eberhard
    Piece-Picking Algorithm Evaluation
    2
  • Piece-Picking in P2P Networks
    When streaming layered videos in a P2P network, the piece-picking algorithm needs to decide which piece to download at which point in time.
    The main goal is to provide the best possible quality with the available bandwidth while ensuring continuous playback and minimizing changes in quality.
    Michael Eberhard
    Piece-Picking Algorithm Evaluation
    3
    View slide
  • Piece-Picking Buffer
    Michael Eberhard
    Piece-Picking Algorithm Evaluation
    4
    • The piece-picking algorithm provides a download strategy for all pieces within the sliding window. View slide
    • The sliding window contains the pieces that are required for playback in the near future.
  • Piece-Picking Sliding Window
    Michael Eberhard
    Piece-Picking Algorithm Evaluation
    5
  • Piece Utility Calculation
    For each piece within the sliding window, the utility is defined as
    Michael Eberhard
    Piece-Picking Algorithm Evaluation
    6
    lj: thelayer of thepiece
    ti: the point in time at whichthepieceisdisplayed
    tk: the point in time of the actualdecision
    dj: thedistortionreductionimportanceof thepiece
    dpijk: theprobability to receivetheusefulpiece in time
  • PieceMapping (1)
    GOPs of 64 framesareconsidered as a unit
    2.56 seconds of contentareprovidedcommonlyforeachlayer (at 25 fps)
    A unitisalwaysentirelydownloaded
    Onlysupportslayeredscalability
    For singlelayercontent, ~16 frames of contentaremapped to a unit
    Michael Eberhard
    Piece-Picking Algorithm Evaluation
    7
  • PieceMapping (2)
    Michael Eberhard
    Piece-Picking Algorithm Evaluation
    8
  • Simulation Setup
    Omnet++/Oversimwithnew P2P protocol and applications (piecepickingalgorithms)
    Swarm of 100 peers, streaming a onehourvideo
    Peer arrivals and departuresaremodeledaccording to a poissondistribution
    Michael Eberhard
    Piece-Picking Algorithm Evaluation
    9
  • Multi/Single LayerComparison
    Bothareencodedwiththesameconstantbitrate and split to fixed-sizepieces
    Qualityforsinglelayerishigherdue to SVC overhead
    Comparisonbased on PSNR, as piecesizeisequalforbothencodings (receivedbitrateis ~equal)
    Thesinglelayer PSNR formissingpiecesisweightedwiththe PSNR of a blackframes
    Michael Eberhard
    Piece-Picking Algorithm Evaluation
    10
  • Full Bandwidth, No Churn
    Michael Eberhard
    Piece-Picking Algorithm Evaluation
    11
  • Full Bandwidth, 10% Churn
    Michael Eberhard
    Piece-Picking Algorithm Evaluation
    12
  • LimitedBandwidth, 10% Churn
    Michael Eberhard
    Piece-Picking Algorithm Evaluation
    13
  • Min/Max Quality/Peer for SL
    Michael Eberhard
    Piece-Picking Algorithm Evaluation
    14
  • Full Bandwidth, IncreasingChurn
    Michael Eberhard
    Piece-Picking Algorithm Evaluation
    15
  • Full Bandwidth, 10% Churn, Frame Loss
    Michael Eberhard
    Piece-Picking Algorithm Evaluation
    16
  • Conclusion
    Layered Video Codecscanbeintegrated in Bittorrent-based P2P system in a backwards-compatible way
    Ifthebandwidthconditionsare not optimal, layeredcodecsprovide a clearlybetterperformance in terms of PSNR
    Michael Eberhard
    Piece-Picking Algorithm Evaluation
    17
  • Thankyouforyour Attention!
    Michael Eberhard
    Piece-Picking Algorithm Evaluation
    18