In this Lecture:
Multimedia Applications
yCategories of multimedia
yExample applications
Ìhow they work
ySome CSCW
Gail Reynard
Gail Reynard — G5CMVR
Gail Reynard — G5CMVR
Main Categories of Multimedia
Interpersonal Communication Speech
yTelephony
yInterpersonal communications
• PSTN, ISDN, cellular phone network, PBX
ÌSpeech, image, text, video…
yInteractive applications over the Internet
yEntertainment applications
yComputer telephony integration (CTI)
• private directory of numbers
• integration with other networked services
yVoice-mail
yAudio teleconferencing
yTelephony over the Internet
• a.k.a. packet voice (uses voice over IP (VoIP))
Gail Reynard — G5CMVR
Site/campus
LAN
Global
Internet
Packet
G/W
Telephony
G/W
Packet-mode
Telephony
G/W
«
«
Packet
G/W
Telephony
G/W
Packet-mode
Circuit-mode
Gail Reynard — G5CMVR
ISP
network
Interpersonal Communication Image Only
yFacsimile
Analog or digital access circuits
• PSTN, ISDN
• PC fax
Circuit-mode
Fax machine
PSTN/ISDN
Gail Reynard — G5CMVR
PSTN or ISDN
«
Gail Reynard — G5CMVR
PC fax
1
Interpersonal Communication Text Only
yElectronic mail
• email server with mailboxes
yUNIX talk
yText-based conferencing
Interpersonal Communication Text and Images
yComputer Supported Cooperative Work
(CSCW)
Ìshared whiteboards
• whiteboard program
• change-notification
• update-control
Ìshared editors
Gail Reynard — G5CMVR
Interpersonal Communication Speech and Video
yVideo telephony (videophones)
yDesktop video conferencing
yMedia Spaces
yVoice mail (multimedia)
Gail Reynard — G5CMVR
Multipoint conferencing
yCentralised mode
Ìused with circuit-switched networks (e.g.
PSTN or ISDN)
Ìcentralised conference server
Ìconnection-oriented
yDecentralised mode
Ìused with packet-switched networks (e.g.
LANs, intranets)
Ìmulticast communications used
Ìconnectionless
Gail Reynard — G5CMVR
Gail Reynard — G5CMVR
Multipoint conferencing (2)
Managing Conferencing Sessions
yData conferencing
yHybrid mode
Ìwhen participants are connected via different
network types
Ìuses a conference server
Ìserver receives data either via individual
circuits or via multicast
Ìgeneral purpose computer as conference server
yAudio conferencing
Ìaudio bridge needed - 6-48 participants
yVideo/multimedia conferencing
Ìmultipoint control unit (MCU) (conference
server)
• multipoint controller (MC)
• multipoint processor (MP)
Gail Reynard — G5CMVR
Gail Reynard — G5CMVR
2
Managing Conferencing Sessions (2)
yUsing an audio bridge
Ìcall scheduled
Ìparticipants call in
yUsing an MCU
Ìcall scheduled
Ìparticipants call in (dial-in mode)
Ìsometimes MCU calls participants (dial-out mode)
Ìtwo display modes
• voice activated switching mode
• continuous-presence mode
Video Conferencing
yPicture-in-Picture (PIP), multiple windows,
single image...
yHigh frame rates - 15-25Hz
yUsed for conferences, meetings, etc.
yCamera, monitor or video window(s)
ySingle or multiple participants
Gail Reynard — G5CMVR
Gail Reynard — G5CMVR
Video Conferencing (2)
Media Spaces
yProvide an “awareness” of a remote space
yOne or more cameras at each site
ySome use document cameras
yDifferent frame rates - 1Hz, 1 frame every
5 minutes...
y“glance” facility (1Hz)
Gail Reynard — G5CMVR
Gail Reynard — G5CMVR
Portholes
Ontario Telepresence System
yAwareness of multiple sites
Gail Reynard — G5CMVR
yInternal system
yCamera, TV monitor,
speaker, microphone
yAllows the set up of
“video calls”
yName list, door state,
message box
Gail Reynard — G5CMVR
3
Ontario Telepresence System (2)
Ontario - Door Access Control
yAllows external video calls
yAllows connection to meeting rooms
Gail Reynard — G5CMVR
Gail Reynard — G5CMVR
Interpersonal Communication Text, Image, Audio and Video
Interactive applications over the
Internet
yMultimedia e-mail
yMultiparty video games
yText, image, audio and video
yWorld Wide Web
Ìinformation retrieval
Ìe-commerce
Gail Reynard — G5CMVR
Gail Reynard — G5CMVR
Entertainment Applications
yVideo on demand
Ìa.k.a. movie on demand
ÌALSO near movie-on-demand (N-MOD) Set-top box
PSTN/cable access network
Video
database
Video
server
Low bit rate
interaction channel
High bit rate channel
for video stream
Gail Reynard — G5CMVR
with integral
high bit rate
modem
Entertainment Applications (2)
yInteractive Television
Ìcable, satellite and terrestrial networks
Ìsubscriber has access to services provided by:
• PSTN
• Internet
Ìsubscriber can actively respond to broadcast
material
Ìa return channel is used typically for:
•
•
•
•
voting
participation in games
home shopping
Gail Reynard — G5CMVR
etc...
4
Interpersonal Communication
ySynchronous communication
ÌAll users are “on-line” at the same time
Ìe.g. video conferencing
Their
People are
communications
colocated
remote
are
•computer assisted telephony
•meeting rooms
•packet telephony
•videophony
•videoconferencing
synchronous
•professional audio/video dist.
•shared workspaces
•shared applications
yAsynchronous communication
ÌUsers may not be logged on at the same time
Ìe.g. email
Gail Reynard — G5CMVR
•argumentation tools
asynchronous
•MM email
•exchange of multimedia docs
•asynchronous computer conferencing
•co-authoring
Gail Reynard — G5CMVR
Summary
yCategories of multimedia
ySome example systems
yMethods of communication
Gail Reynard — G5CMVR
5