Upload
videoguy
View
207
Download
1
Tags:
Embed Size (px)
DESCRIPTION
Citation preview
Nicos IoannouNicos Ioannou
University of CyprusUniversity of Cyprus
15/2/200415/2/2004
Real Time Distance Education Real Time Distance Education Systems and TechnologiesSystems and Technologies
ContentsContents Introduction Video Conferencing systems
Endpoints MCU, Gatekeeper, Gateway
Data Collaboration tools VRVS Net meeting
Streaming technologies Live Streaming Video on Demand
IntroductionIntroduction
Provide information about Real Time Provide information about Real Time Distance Education systems and Distance Education systems and services services
Share knowledge and experiences Share knowledge and experiences among participantsamong participants
Video ConferencingVideo Conferencing EndpointsEndpoints
Multipoint Control UnitsMultipoint Control Units
GatewaysGateways
GatekeepersGatekeepers
VideNet and Global Dialing SchemeVideNet and Global Dialing Scheme
EndpointsEndpoints Software-based
Generally slow and non-standard; not very satisfactory.
Examples: Microsoft NetMeeting Hardware-based, plug into PC USB Port
Newest approach; will become ubiquitous Examples: Polycom ViaVideo, VCON ViGo.
Hardware-based, PCI-bus cards install inside PC Added features and controls, beyond USB systems. Examples: Zydacron Z340, VCON Escort 25.
Hardware-based, standalone, no PC involved Easiest to use, best quality. Example: Polycom Viewstation
Standalone EndpointsStandalone Endpoints
Set-topSet-top 500, 800500, 800
DesktopDesktop 10001000
Complete systemComplete system 2500, 6000, 70002500, 6000, 7000
Multipoint Control Unit Multipoint Control Unit (MCU)(MCU)
Allows more than two people to be in a videoconference.
May be physically located anywhere on Earth. Functions as an Internet server for
videoconferencing. Every person’s audio is always heard by all
others. Video from the person who talks loudest is
seen by all. Multiple MCUs may be cascaded together for
larger videoconferences. Or used separately for more simultaneous videoconferences.
GatewayGateway
Joins H.320 ISDN video calls with H.323 Internet video calls.
Calls may be initiated from either side.
May be physically located anywhere on Earth.
Multiple gateways may be used for more simultaneous calls.
GatekeeperGatekeeper Controls all MCUs, gateways and clients in its
“zone”. A zone is any collection of H.323 devices you choose to work closely together. The devices may be physically located anywhere on Earth.
There can be only one active gatekeeper in a zone.
May be physically located anywhere on Earth. May be physically located in an MCU, a
gateway, a router, or a PC. But it is independent of them.
Provides calling with “telephone numbers” and nicknames, instead of IP addresses. A gatekeeper is analogous to a domain name server, in this sense
VideNetVideNet A test-bed for exploring issues A test-bed for exploring issues
associated with the creation of the associated with the creation of the global integrated video/voice over IP global integrated video/voice over IP environmentenvironment
An interconnected network of h.323 An interconnected network of h.323 zoneszones
A community of users sharing A community of users sharing informationinformation
video to every person on Earth ...
Global Dialling SchemeGlobal Dialling Scheme E.164/tel.no. integrationE.164/tel.no. integration Implemented by present gatekeeper Implemented by present gatekeeper
technologytechnology
Data Collaboration Data Collaboration • Allows remote participants to take Allows remote participants to take
control of the application or desktop on control of the application or desktop on the host computer.the host computer.
• Provides additional features such as Provides additional features such as instant messaging, whiteboard, chat, instant messaging, whiteboard, chat, and file sharing.and file sharing.
• Provides a persistent virtual workspace.Provides a persistent virtual workspace.• Provides tools such as agenda, task list, Provides tools such as agenda, task list,
project planning, calendar, discussion, project planning, calendar, discussion, outliner, etc…outliner, etc…
Data Collaboration Tools Data Collaboration Tools VRVSVRVS
From the Physics communityFrom the Physics community Tens of reflectors, thousands of users, Tens of reflectors, thousands of users,
thousands of hours usedthousands of hours used SchedulingScheduling
Netmeeting, MessengerNetmeeting, Messenger Free from Microsoft windowsFree from Microsoft windows
VRVS ToolVRVS Tool
StreamingStreaming Media Media
Streaming is the one-way delivery of digital Streaming is the one-way delivery of digital content from a streaming server to a streaming content from a streaming server to a streaming client in a continuous, paced, and controlled client in a continuous, paced, and controlled flow.flow.
Streaming alleviates the need to download an Streaming alleviates the need to download an entire media clip as a file.entire media clip as a file.
Live events don’t exist as a file yet!Live events don’t exist as a file yet! Allows playing to start before download is Allows playing to start before download is
completedcompleted Protects copyrightProtects copyright
StreamingStreaming Media Media
Live StreamingLive Streaming Μετάδοση σε πραγματικό χρόνοΜετάδοση σε πραγματικό χρόνο Όλοι οι clients βλέπουν την ίδια ροή Όλοι οι clients βλέπουν την ίδια ροή
ταυτόχροναταυτόχρονα Μετάδοση με multicast και unicastΜετάδοση με multicast και unicast
Video on DemandVideo on Demand Μετάδοση αποθηκευμένων αρχείωνΜετάδοση αποθηκευμένων αρχείων Οι clients παρακολουθούν τη ροή κατ’ απαίτησηΟι clients παρακολουθούν τη ροή κατ’ απαίτηση Μετάδοση με unicastΜετάδοση με unicast
Live StreamingLive Streaming
PictureTel
Streaming server
PictureTel
ΔΙΚΤΥΟ ΚΕΑΔPlayer
<150Kbps
>150Kbps
Sure Stream
Sure Stream
Encoder
Player
Video on DemandVideo on Demand
PictureTel
PictureTel
ΔΙΚΤΥΟ ΚΕΑΔ
Player
Player
Video On Demand Server
Q&AQ&A