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Chameleon: Adaptive Peer-to-Peer Streaming

with Network Coding

Anh Tuan Nguyen, Baochun Li, and Frank Eliassen

Department of Informatics, University of Oslo, Oslo, Norway

IEEE INFOCOM 2010

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Outlines

Introduction Chameleon: Adaptive P2P Streaming with Ne

twork Coding Performance Evaluation Conclusion

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Introduction

Current P2P streaming systems PPLive, PPStream, TvAnt, SopCast, TVUPlayer…

Their limitationsProvide the same Quality of Service

to all their customers regardless of network conditionsend-device’s characteristicsuser preferences

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Introduction

▪ Approach: Scalable Video Coding + P2P networking▪ An original SVC stream can be filtered to produce video of

different qualities, spatial resolution, and frame rates

Source: http://ip.hhi.de/imagecom_G1/savce/

-> adaptability-> expressiveness

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Introduction Motivations for using network coding

peer coordination Peer coordination is critical to the system performance because it controls the collaborati

on of sending peers to utilize available bandwidth from each sender to maximize the delivered quality at the receiving peer.

quality adaptation The purpose of quality adaptation is to avoid playback skips and to maximize the video q

uality when bandwidth variations occur.

Exploiting Network Coding coding at intermediate nodes in the overlay networks all pieces of information are treated equally; every packet encoded by a peer

is innovative to others Benefits

reduce delivery time among peers increase the potential for peer collaboration make the system more resilient to peer dynamics and bandwidth variations

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Introduction Combining network coding with SVC

SVC prioritizes video data to provide different quality levels by allowing the extraction of substreams.

Network coding makes data packets equally important to ease the data delivery, and the original data is only recovered when enough linearly independent blocks are received. With network coding, a peer only needs to check if it has recei

ved a sufficient number of linearly independent coded blocks, without being concerned with who has been sending them.

Since coded blocks are equally useful to the receiver, the responsibilities of a particular sender can be easily transferred to other senders if it leaves the system.

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Layered Video Single layer Video

All peers receive the same video quality PPStream, PPLive, CoolStreaming

Layered video A video is encoded into several layers More layers introduce better video quality Nested dependence between layers A higher layer can be decoded only if all the lower layers are available

Higher upload contribution results in better received video quality

L4

L3

L2

L1

L2

L1

7http://www.powercam.cc/slide/609

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Multiple Description Coding (MDC)

Video encoding/decoding technology Video content is encoded into several descriptions Each description can be decoded independently Even receiver only receives one description, the video is

displayed with low quality The more descriptions received, the better video quality Compatible for transmitting video streaming in the Internet

encoding

MDCVideocontent

decoding

MDC

# of description

Vid

eo

qu

ality

8http://www.powercam.cc/slide/609

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Scalable Video Coding (SVC)

SVC is an extension to the H.264/MPEG4-AVC video coding standard. To extend the wide range of:

Temporal Scalability. Spatial Scalability. Quality Scalability.

An SVC bit-stream consists of a base layer and several enhancement layers. The base layer is a plain H.264/MPEG4-AVC bit-

stream for backward compatibility.

http://www.powercam.cc/slide/111

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Scalable Video Coding (SVC)

Spatial decimation

Temporal scalable coding

Temporal scalable coding

Prediction

Prediction

Base layer coding

Base layer coding

SNR scalable coding

SNR scalable coding

Scalable bit-stream

Base Layer

Enhancement Layer

http://www.powercam.cc/slide/111

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Fig. 1. An example of the SVC structure. (a) An AU consisting of 4 LRs. (b) A GOP consisting of 8 pictures (AUs) and coded with hierarchical B-pictures. The symbols Tk specify the temporal layers with k representing the corresponding T_ID. The numbers below specify the coding order. (c) A coded video sequence.

•LR (Layer Representation)•An Access Unit (AU) consists of all LRs that represent an original picture.•IDR (Instantaneous Decoding Refresh)

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Fig. 2. The store order of the entities in the video file.

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Fig. 3. An example of the segmentation method where the stream has 3 quality levels and is divided into segments of 2 GOPs. The symbols QL(quality level) k specify Q_ID = k.

A segmentation method to use SVC in P2P

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Fig. 4. An example of the combination of network coding and SVC. Packet 1, 2, and 3 are divided into n, m, and k blocks, respectively. Network coding with different number of unknowns (n, m, and k) is used for different quality levels.

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Chameleon: Adaptive P2P Streaming with NC and SVC

The primary design goal of Chameleon is to effectively utilize available bandwidth capacity of each peer to maximize delivered quality under bandwidth variations.

A streaming protocol designed to incorporate NC with SVC.Adapts to network fluctuationsOffers low skip rates and high quality satisfaction

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Architecture

-Invoked when peer joins or when peer wants to improve quality level (periodically)-Forms/maintains the overlay.

-Invoked when the status of the playback buffer changes

- adds/keeps/drops quality level

-Selects potential senders to send layer requests-Sends request to selected senders

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Class-based Vs. Quality-based Neighbor Selection

•Peers are classified into classes based on their bandwidth capacity

•A peer connects to other peers in the following priority•Peers of the same class•Peers of higher classes•Peer of lower classes

•If more peers than needed, choose randomly

•Each peer calculates the average quality level it has perceived so far.

•When a peer selects a neighbor, it will choose the peer whose average quality level is closest to it class.

•If more peers than needed, choose randomly.

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Quality Adaptation

The status of the playback buffer with two thresholds add_threshold drop_threshold

Ex: we set drop_threshold = 6, and add_threshold =drop_threshold+δ, δ=2, ..., 12.

Fig. 7. The playback buffer in Chameleon: The dark shade indicates the receiving status of each segment.

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Adaptation Graph

(1): playback skip(2): buffering effect

Aurora Workshop, Oslo 24-26

Fig. 9. An example of the playback graph of a typical peer.

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Quality Adaptation

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Sender Selection

Random-based Vs. Heuristic-based selectionClosest available bandwidth capacity (maximize

available bandwidth capacity utilization)Smallest number of available layers (maximize

available layer utilization)

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Peer Coordination

Receiver-driven approach Each receiver:

sends requests for the lowest unavailable layer to all senders. progressively decodes arrived blocks when having received enough linearly independent blocks, sends

a stop notification (via buffer maps) to the senders, finishes the decoding process

Each sender: on receiving a request, performs network coding on available block

s of the requested layer, and sends newly coded blocks to the requesting peers automatically and continuously as soon as possible

on receiving a stop notification, stops sending

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Performance Evaluation

Environment JSVM Software,

Version 9.17 generate a real two-

hour video sequence 4 quality levels

(average bit rate) level 1: 620 Kbps level 2: 825 Kbps level 3: 945 Kbps level 4: 1065 Kbps

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Performance Evaluation

Performance metrics Playback skip rate: the percentage of segments skipped during playback. Average quality satisfaction: the average quality satisfaction of the

system.

playbacksTotal

skipsPlaybackrateskipAverage

_

___

levelqualityExpected

levelqualityPerceivedonsatisfactiqualityAverage

__

____

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Performance Evaluation

•Vary the number of peers from 70 to 700. Peers join the network randomly, and stay connected until the session ends.• Chameleon achieves very low skip rates.• The quality satisfaction of Chameleon is always greater than 90%.

Fig. 11. The performance of Chameleon and FABALAM in different network sizes.

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Performance Evaluation

Peer Dynamics use the Weibull distrib

ution — Weibull(k, 2) With a two-hour stre

aming session, we use 3 different values of k = 2000, 4000, and 6000 to generate different mean lifetimes.

The network size is 350. Fig. 12. The effects of peer dynamics on Chameleon.

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Performance Evaluation

• Chameleon can adapt to peer dynamics well to achieve stable performance, whereas the performance of FABALAM is much impacted by peer dynamics.

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Conclusion

We present the design and the performance evaluation of Chameleon, our new adaptive P2P streaming protocol that combines the advantages of network coding and SVC.

With Chameleon, we demonstrate that the combination of network coding and SVC is feasible and beneficial.

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[5] M. Wang and B. Li, “R2: Random Push with Random Network Coding in Live Peer-to-Peer Streaming,” IEEE Journal on Selected Areas in Communications, vol. 25, no. 9, pp. 1655–1666, Dec. 2007.

[6] Y. Cui and K. Nahrstedt, “Layered peer-to-peer streaming,” in Proc. of NOSSDAV, Jun. 2003, pp. 162–171.

[7] Y. Liu, W. Dou, and Z. Liu, “Layer Allocation Algorithms in Layered Peer-to-Peer Streaming,” in Proc. of IFIP international conference on network and parallel computing (NPC) , Oct. 2004, pp. 167–174. [FABALAM]

[8] R. Rejaie and A. Ortega, “PALS: Peer-to-Peer Adaptive Layered Streaming,” in Proc. of NOSSDAV, Monterey, CA, USA, jun 2003, pp. 153–161.

Anh Tuan Nguyen, Baochun Li, Frank Eliassen. “Quality- and Context-aware Neighbor Selection for Layered Peer-to-Peer Streaming,” in the Proceedings of IEEE International Conference on Communications 2010 (IEEE ICC 2010), Cape Town, South Africa, May 23-27, 2010.