TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 1 Design and Evaluation of a...
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![Page 1: TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 1 Design and Evaluation of a Multi-User Virtual Audio Chat Lea Skorin-Kapov R&D Center,](https://reader036.fdocuments.us/reader036/viewer/2022062318/5514c54d550346b0338b4ad5/html5/thumbnails/1.jpg)
TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 1
Design and Evaluation of a Multi-User Virtual Audio Chat
Lea Skorin-Kapov
R&D Center, Ericsson Nikola Tesla,
Zagreb, Croatia
Maja Matijašević
FER, University of Zagreb, Croatia
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 2
Presentation Outline
• Introduction
• Research issues
• Development of Virtual Audio Chat (VAC)
• Performance evaluation
• Conclusions
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 3
Introduction
• Virtual Reality (VR): interactive, immersive, multisensory, 3D synthetic environment
• VR service issues that dictate QoS requirements:– Rich VR/multimedia content– Perceived “real-time” interactivity– Multiple users
• Problem: different representations of QoS at user/application level and at communication level
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 4
• Research has mainly progressed in two complementary directions:– Performance of virtual reality end systems– Virtual reality communications
• Limited research on relating user perceived system performance with quantitative network parameters in distributed VEs
• Our Goal: address relationship between network and application level parameters
• Interconnection model used for reference
Research issues
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 5
• Attempts to present common issues in different VR
applications• User view: seamless virtual world, composed of shared
virtual objects and media streams (“trans(ient) objects”),
and modified by simulation and/or user interactions• Spatial composition: objects’ media components• Distribution/synchronisation: replication of distributed
objects and synchronisation for streams• Media connectivity: different media profiles - mapping to
transport level QoS parameters
NVR Interconnection Model (1)
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 6
NVR Interconnection Model (2)ObjectUV
Replicationprofile
a v
MC Media profile Media profile
(QoS) Media connectivity (best effort)
Stream mapping
SharedObject
Audiocont.
Videocont.
Textcont.
Media containerGeometry3D graphics2D graphics
audio video textcombined
SC
TransObject
Data,graphics
Replication Stream synchronization (inter-stream)
Media synchronization (intra-stream)DS
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 7
Development of Virtual Audio Chat
• Audio conference with (desktop) virtual reality interface
Three basic components:
• VRML mobile phone model
• Java applet opening RTP based audio conference
– Java Media Framework (JMF) API used
• Modified Session Directory (sdr) tool – enables user to
schedule and announce multimedia session
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 8
VRML mobile phone model
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 9
Virtual bufferInteraction with mobile keys
Animation
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 10
Real-time data transfer using RTP/RTCP
Application A Application B
Decoding Encoding
RTP RTCP
UDP/IP (multicast)
Figure adapted from “Internet Protocols for Multimedia Communications”, T. Braun , IEEE MultiMedia, 1997
DecodingEncoding
RTPRTCP
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 11
Modified session directory (sdr) tool• Sdr – scheduling/announcing multimedia sessions on the
MBone
• Modified by enabling new media type: vrml_audio
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 12
VAC interconnection model
graphics
ReplicationDS
MCMedia connectivity
SharedObject
Geometry3D graphicsSC
Profile 1
Stream synchronization (inter-stream)
Profile 2
TransObject
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 13
Performance Evaluation
• RTP/RTCP packet throughput
• Interactivity
– quantitative interactivity parameters
• Immersion
– quantitative immersion parameters
– jitter and packet loss
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 14
RTP/RTCP packet throughput
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 15
Interactivity
• Relating to scope and extend of user interactions in a VE
• Empirical approach using a questionnaire used to obtain user evaluation
• Can be quantified as combination of sensory support, navigation, and user representation
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 16
Object selection and manipulation
Interactions
None (viewer)User appearance (avatar quality)
Examine, fly, walkNavigation technique
Pointer (2D) recognitionCommand input
Mouse trackingVirtual controls
Tracking
ValueParameter
Quantitative interactivity parameters
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 17
Immersion
• Presentation quality of (multi) sensory information that user perceives as a 3D synthetic environment
• Quantified as combination of visual, auditory, and haptic immersion
No spatializationSound spatialization
Phone quality (8000 Hz, 8 bit/sample)
Sound quality
ValueParameter
Quantitative immersion parameters
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 18
• Measurements of jitter and packet loss using rtpmon tool – reads RTCP packets generated by users
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 19
Conclusions
• A simple multi-user interactive VR/Web application has
been designed and developed
• The overall approach, from model to implementation, is
general and may be applied to a wide range of virtual
reality applications
• Performance results may be used for application
improvements (as perceived by the user) as well as for
resource reservation
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TERENA NETWORKING CONFERENCE 2002 03. - 06.2002., Limerick Ireland 20
DEMO!