T.Sharon-A.Frank

Distributed Education

Video Conferencing

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Contents

• What’s the idea?

• Conferencing aspects

• VC Dimensions

• VC Layered Architecture

• VC Standards

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What’s the Idea?

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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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Multimedia Conference via Skype

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The Meeting Room Conference

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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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Whiteboard

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Conference Configuration

Video cardVideo card

Communication

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VC Network

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Network Conferencing

SCN

Switched CircuitNetwork (SCN)

InternetLAN TCP/IP

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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 System Types

• Meeting Rooms

• Roll-about

• Personal (Desktop)

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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.

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An Example TelePresence Conference