Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner, Osama - - PowerPoint PPT Presentation

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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner, Osama - - PowerPoint PPT Presentation

Jan 19, 2023 355 likes •561 views

Institute of Computer Science Chair of Communication Networks Prof. Dr.-Ing. P . Tran-Gia Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner, Osama Abboud, Oliver Hohlfeld, Tobias Hossfeld, Phuoc Tran-Gia

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Institute of Computer Science Chair of Communication Networks

  • Prof. Dr.-Ing. P

. Tran-Gia

Towards a QoE-aware P2P Video-on-Demand System

Thomas Zinner, Osama Abboud, Oliver Hohlfeld, Tobias Hossfeld, Phuoc Tran-Gia zinner@informatik.uni-wuerzburg.de 24.11.2010

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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 2

Live Streaming vs. VoD

Network Parameters Impact on Live Streaming (UDP) Impact on VoD (TCP)

Packet loss Loss of information, artifacts, stalling, stream starvation Retransmissions, impact on TCP control loop Insufficient available bandwidth Leads to packet loss Higher startup delay, frequent stalling Delay Higher startup delay, less “live” experience Higher startup delay, possible impact

  • n bandwidth

Jitter May lead to packet loss (jitter buffer to small; VLC e.g. 300 ms) Practically none

 P2P Live Streaming: Video content encoded on-the-fly and delivered to all peers nearly simultaneously  P2P VoD Streaming: Video content already available, different play back positions of the peers

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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 3

Motivation – P2P VoD Streaming

Core Network

Access Network Access Network Access Network Support different access technologies Support different user devices

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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 4

Agenda

 Motivation  QoE for video transmissions

  • QoE management
  • Impact of QoS on QoE

 P2P VoD System

  • Peer and chunk selection mechanisms
  • Scalable video coding
  • Scenario description and results

 Conclusion

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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 5

QoE Management

 QoE degradation due to bad network conditions, e.g. bandwidth

  • empty buffers and stalling (TCP)
  • packet loss and artifacts / stream starvation (UDP/RDP)

Negative, uncontrollable impact on the QoE (success related)

 Bandwidth saving feasible by reducing:

  • resolution
  • frame rate
  • image quality

Negative, but controllable impact

  • n QoE (resource related)

 Comparison of the different impact factors on the video QoE

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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 6

Motivation – Scalable Video Codec

 Many forms of internet

connections

 Possible solutions

  • Same file for each

device and connection

  • One file for each device

and connection

  • One multi-layer file

 Scalable video codec

  • Adapted to user‘s

requirements

SVC

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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 7

H.264 / SVC

 Extension of H.264/AVC single layer codec  Encoding in one bit

stream with different qualities:

  • resolutions (spatial)
  • frame rates (temporal)
  • image quality (quality)

 Enables code adjustments with

respect to:

  • user device
  • network conditions

 Seamless switch between different layers enables QoE management

Temporal Scalability

CIF 15 Hz Q0 CIF 30 Hz Q0 CIF 60 Hz Q0 SD 15 Hz Q0 SD 30 Hz Q0 SD 60 Hz Q0 HD 15 Hz Q0 HD 30 Hz Q0 HD 60 Hz Q0 15 Hz 30 Hz 60 Hz

Spatial Scalability

CIF SD HD

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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 8

Delivery-Provisioning Hysteresis

 Controlled and uncontrolled video distortion as function of

goodput (application perceived throughput)

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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 9

Frame Rate vs. Resolution

 720p video clip with 30 fps provided best user perceived quality  Resolution / Image quality reduction outperforms frame rate

adaptation in terms of bandwidth savings and video quality

20.09.2010 20.09.2010

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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 10

QOE-AWARE P2P-VIDEO-ON- DEMAND SYSTEM USING SVC

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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 11

P2P-VoD based on Tribler

 P2P VoD System Tribler (P2P-Next)  BitTorrent extension

  • Designed for file-sharing

 Adapted peer and chunk selection algorithms:

  • Give2Get algorithm replaces Tit4Tat
  • Chunk selection modified w.r.t. time awareness

 Suitable for VoD services  Our approach: Enhance Tribler to support scalable video coding

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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 12

SVC Chunk Selection

 Arrangement in

priority windows

 Adaptation of priority window

appraoch to SVC

 Lower enhancement

layers are favored

 Temporal enhancement layers are

prefered to spatial ones

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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 13

Objective Quality of Experience

 Parameters measured in simulation study

  • Based on Protopeer

 Average number of layers played out

  • One value for temporal, spatial scalability each

 Delay to playout start interval

  • Time interval from peer start event to playout start

 Stalling times

  • Sum of all stall events of one peer

 Length of the inter quality switching time

  • Vector of all time intervals with same quality
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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 14

Investigation of Different Seeding Strategies

 Scenario setup:

  • Two peer classes: DSL 1000, DSL 2000 with 128 kbps, 192 kbps

upload capacity

  • 40 server with 512 kbps upload capacity (each 4 upload slots)

 Comparison of two seeding strategies:

  • Normal seeding strategy: no download after watching the video
  • Interested after strategy: chunks demanded after watching the video

 Investigation with regards to remaining online time

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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 15

Impact on Playback Quality

 Normal seeding strategy better at small seeding times  More enhancement layers for DSL 2000 peers  Increased quality with longer remaining online time 600 800 1000 1200 1 1.5 2 2.5 3 Average Number of Layers Remaining Online Time (s) interested after strategy normal seeding strategy DSL 1000 DSL 2000

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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 16

Impact on Initial Delay

 Reduced delay with increasing remaining online time  No difference between peer classes  Normal seeding strategy outperforms interested after strategy 600 800 1000 1200 20 30 40 50 60 Remaining Online Time (s) Delay to Playout Start (s) interested after strategy normal seeding strategy DSL 1000 DSL 2000 DSL 1000 DSL 2000

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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 17

Conclusion

 Influence of network QoS on user perceived quality for video streaming:

  • Controlled quality degradation outperforms uncontrolled degradation
  • Frame rate adaption should be avoided

 Discussion of a QoE-aware P2P VoD system:

  • Enables easy adaptation of user‘s QoE to provided resources
  • Peers which finished play back should not download further chunks

 Future work:

  • Further investigation of P2P VoD (including measurements)
  • Enhancement of QoE Hysteresis with FEC
  • QoE Model for Stalling
  • Media-aware network element for maximizing QoE for SVC streams
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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 18

Q&A

Thank you for your attention !

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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 19

Impact on Stalling

 No stalling times with normal seeding strategy  Remaining online time of 900 s with interested after strategy  Smaller stalling times for DSL 2000 peers

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Towards a QoE-aware P2P Video-on-Demand System Thomas Zinner 20

Tribler Peer Selection

 Based on G2G algorithm

  • Prefers peers with

good uploading behavior

  • Discourages free

riders

 Rates every peer before

sending data

 Asks grandchildren

about peer-behavior

uploader downloader

request unchoking unchoking request grandchildren list