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Contents
• What’s the idea?
• Conferencing aspects
• VC Dimensions
• VC Layered Architecture
• VC Standards
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What is it used for?
• Social Encounters
• Job Interviews
• Business Meetings
• Distance Learning
• Medical Consultation
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Conference Types
• Chat Conference (IRC, Chat)
• Audio Conference (WebPhones)
• Video Conference (VC Tools)– Bi-party Conference
– Multiparty Conference (Reflector, MeetingPoint):» Group Communication» Needs Floor Control
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VC Hardware
• Cameras
• Screens
• Speakers and Microphones
• Other Aids (Electronic Board, Remote Control)
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VC Software/Tools
• Chat
• Video/Audio tools
• Whiteboard
• Data/File Transfer
• Application Showing
• Application Sharing
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VC Dimensions
Networking
System Types
Infrastructure
Packet-switched Networks
Circuit-switched Networks
Desktop
Roll-about
Meeting roomsHardware oriented
Software oriented
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VC Networking
• Circuit-Switched Networks– POTS
– ISDN
• Packet-Switched Networks– LAN
– WAN
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VC Systems Examples
• Meeting Rooms Systems:– VTEL TC2000– PictureTel Concorde 4500
• Roll-about Systems:– VTEL F.R.E.D– PictureTel Swiftsite
• Personal (Desktop) Systems: – MS NetMeeting – CU-SeeMe
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VC Layered Architecture
User Interface
Tools/Utilities
Video Codecs
Audio Codecs
Hardware Devices
Communication Infrastructure
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Architectural Aspects
• Audio aspects– Appropriate Codecs
– Half/Full Duplex
– Echo
– Delay
• Video aspects– Appropriate Codecs
– Frame size (SQCIF, QCIF, CIF)
– Delay/Jitter
• General aspects– Call Control
– Channels and Multiplexing
– Synchronization (lips-synch)
– Group Communication (floor control, Multicasting)
– Quality of Service (QoS)
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Voice Quality - QoS
The Objective:Provide
unfailing, ubiquitous, toll quality service
0
200
400
160
0 1 5 10
Service Level Agreement Violation
Area of Unacceptable Operation
On
e-W
ay D
elay
(m
s)
Marginal Acceptance
Acceptable Operation
Packet Loss)%(
high threshold low threshold
The Challenge:Eliminate the impact of delay-insensitive traffic on real-time
traffic
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QoS Parameters
Best High Medium Best
Effort
Mouth-to-
Ear Delay:
0ms -
150ms
150ms -
250ms
250ms -
450ms
450ms and
above
Call
Setup:
0 sec - 1
sec
1 sec - 3
sec
3 sec - 5
sec
5 sec and
above
few ms
echo path
PSTN PSTNGG IP network
ECEC
hundred ms
few ms hundred ms few ms
few msDelay Budgets
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VC Standards
• Overall Standards: H.320, H.323, H.324
• Call Control: H.245
• Video Codecs: H.261, H.263, M-JPEG
• Audio Codecs: G.7XX
• Data Conferencing: T.120
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TelePresence Conference
• Set of technologies allowing a person to feel as if they were present, at a location other than their own one.
• Requires good lighting and screens installed with speakers.
• Transmits the user's position, movements, and voice to the remote location.
• Enables the same transfer for both ends, allowing interactive dialogue.
• Delivers an 'in person' experience, allowing meetings without travelling.