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  • 1Petri Vuorimaa 1

    Video conferencing

    Introduction Standards Products Internet telephony Computer Telephony Integration (CTI)

    Petri Vuorimaa 2

    Introduction

    Video conferencing can be used for+ Audio-visual communication+ Sharing of documents, tables, pictures, etc.

    Several benefits+ Traveling costs+ Response time+ Better understanding (body language)

    Petri Vuorimaa 3

    Systems

    Two main types:+ Video conferencing rooms+ Video conferencing software

    Video conferencing rooms are for group meetings+ Organization either has it own premises or rents them

    from operator

    Video conferencing software is for personal use

    Petri Vuorimaa 4

    Equipment

    Video/audiocapture

    Modem, ISDNor LAN

    Audiocard

    Communicationnetwork

    Petri Vuorimaa 5

    Group Meetings

    Two types of video conferences:+ Point-to-point conferences (video telephony)+ Multipoint conferences (group meetings)

    In group meetings, there are two ways to share turns (i.e., floor control):+ Automatic selection (e.g., based on audio)+ Chairman

    Petri Vuorimaa 6

    Multipoint Conferences

    Communicationsnetwork

    Multipoint server

  • 2Petri Vuorimaa 7

    Standard Families

    Integrated Services Digital Network - ISDN (H.320)

    Networks supporting QoS (H.310, H.321, and H.322)

    Local area networks - LAN (H.323) Plain old telephone systems - POTS (H.324) Shared workspaces (T.120)

    Petri Vuorimaa 8

    Standard families (cont.)

    Petri Vuorimaa 10

    H.320

    Petri Vuorimaa 11

    Video

    Two resolutions:+ Quarter Common Intermediate Format (QCIF): 176 x

    144+ Common Intermediate Format (CIF): 352 x 288

    Frame rates 7.5, 10, 15, or 30 frames per second Motion estimation can be used, but is not

    necessary

    Petri Vuorimaa 12

    Audio codecs

    Three different audio codecs:+ G.711 48-64 Kbps narrow band+ G.722 48-64 Kbps wide band+ G.728 16 Kbps narrow band

  • 3Petri Vuorimaa 13

    Different classes

    Petri Vuorimaa 14

    H.324

    Petri Vuorimaa 15

    H.324

    Meant for Plain Old Telephone Systems (POTS) H.263 can be used for below 64 Kbps video

    coding+ sub-QCIF (128 x 96), QCIF (176 x 144), CIF (352 x

    288), 4CIF (702 x 576), and 16CIF (1408 x 1152)

    G.723.1 audio codec transmits at 5.3 or 6.3 Kbps

    Petri Vuorimaa 16

    H.324 (cont.)

    Can use even 28.8 and 33.3 Kbps modems (V.34) Codecs are better, but quality is worse than H.320

    + H.320 has much more bandwidth than H.324

    Petri Vuorimaa 17

    H.323

    Petri Vuorimaa 18

    H.323

    LANs (Internet & Intranet) without QoS support Clients, multipoint servers, gateways and

    gatekeepers Real-time transport protocol (RTP) New audio codec G.729 (8 Kbps)

  • 4Petri Vuorimaa 19

    Gateway

    The gateway allows the integration of H.323 networks with other networks

    Tasks:+ transformations between media formats+ transformations between communication protocols+ transformations between audio and video codecs+ connection setup and tear-down

    Petri Vuorimaa 21

    Gatekeeper

    Gatekeeper takes care of resource reservations The amount of simultaneous users can be limited Transforms connection requests from outside to

    internal addresses and vice versa

    Petri Vuorimaa 22

    Multipoint Server

    Required when three or more clients participate the conference

    Is composed of two parts:+ Multipoint Controller takes care of connections+ Multipoint Processor(s) transform(s) media streams

    Processors can also combine streams:+ Mixing+ Switching

    Petri Vuorimaa 23

    Multipoint Server (cont.)

    Videoconferences can be set up in three different ways:+ unicast, multicast, and broadcast

    Three ways of practical implementation:+ centralized, distributed, and hybrid

    In practice H.323 is implemented on top of IP etc. protocols

    Petri Vuorimaa 24

    Different alternatives

  • 5Petri Vuorimaa 25

    Protocol stack

    Petri Vuorimaa 26

    T.120

    Implements the extra services:+ conformance+ image transfer+ shared workspaces+ file transfer+ multipoint conferences

    Petri Vuorimaa 27

    T.120 (cont.)

    T.120 is composed of three layers:+ transport layer+ protocol layer+ application layer

    Transport layer is divided into three levels:+ transport protocol+ multipoint conference+ conference control

    Petri Vuorimaa 28

    Transport layer

    Petri Vuorimaa 29

    T.120 (cont.)

    Protocol layer is composed of+ image transfer (T.126)+ binary file transfer (T.127)+ share application transfer (T.Share)+ resource reservation (T.RES)

    New standard family T.130 is under development

    Petri Vuorimaa 30

    Products

    Video conference bridges Video networks Video conference rooms Workstations Gatekeepers Gateways

  • 6Petri Vuorimaa 31

    Video conference bridges

    Support primarily H.320 and T.120 standard families

    Allow multipoint video conferencing Support few tens of users Participants either call to the bridge or the bridge

    setups the connections itself

    Petri Vuorimaa 32

    Video networks

    Best possible image quality Intended primarily for conferences Uses either ISDN or ATM network

    Petri Vuorimaa 33

    Video conference rooms

    Intended for video conferencing Maintained by companies or operators Based on H.320 (ISDN) standard family H.323 (Internet) standard family is coming

    Petri Vuorimaa 34

    Workstations

    LAN, ISDN, or modem card Audio and video cards Software (e.g., Microsoft Netmeeting, Picturetel,

    Intel) H.320 most common, but H.323 is coming (client

    software is available)

    Petri Vuorimaa 35

    Gatekeepers

    Required by H.323 standard family For example, Intel LANDesk Conferencing

    Manager+ automatic gate keeper+ zone management+ outbound route management+ incoming call routing

    Petri Vuorimaa 36

    Gateways

    Intel LiveGateway+ bi-directional connection between H.323 and H.320

    systems+ format transform between H.323 and H.320 systems+ supports also H.320 multipoint server+ four gates in on PC+ either local or gate keeper based administration

    Both Intel LANDesk Conferencing and LiveGateway are Windows NT based

  • 7Petri Vuorimaa 37

    Internet telephony

    With suitable hardware and software computers connected to Internet can be used for telephony

    No extra charges, but the quality is not very good Gateways to ordinary telephone network also

    available

    Petri Vuorimaa 38

    Internet telephony (cont.)

    Petri Vuorimaa 39

    Internet telephony (cont.)

    Some long distance operators use Internet connections for telephony

    Allows the use of compression For example, 64 Kbps -> 2.4 Kbps

    Petri Vuorimaa 40

    Calls within organization

    Petri Vuorimaa 41

    Public Internet calls

    Petri Vuorimaa 42

    Internet telephony products

    Microsoft Netmeeting supports H.323 and T.120 standard families

    Includes H.263 video codec Compatible with Intel and PictureTel products Utilizes Intel Pentium MMX technology Other products include White Pine Software CU-

    SeeMe, IBM Internet Connection Phone, VDOnet VDOPhone

  • 8Petri Vuorimaa 43

    CTI

    Computer Telephony Integration (CTI) integrated computers and telephones

    Brings savings and increases efficiency (invest return time usually under year)

    Several different implementations

    Petri Vuorimaa 44

    CTI block diagram

    Petri Vuorimaa 45

    CTI applications

    Voice mail (answering service) Automatic call transfer Intelligent call routing and distribution (call

    centers) Voice text (timetable, etc.) Fax requests (information delivered via fax)

    Petri Vuorimaa 46

    CTI applications (cont.)

    Interactive telephone services (reservations, orders, etc.)

    Call records (automatic recognition of customers) Gateways (video conference with standard

    telephone) Call management (automatic dialing)

    Petri Vuorimaa 47

    CTI implementations

    CTI can be based on separate server Another alternative is to join telephone directly to

    workstation Video conference, Internet telephony, and CTI

    systems can be integrated

    Petri Vuorimaa 48

    Call Center

  • 9Petri Vuorimaa 49

    Integrated system

    Petri Vuorimaa 50

    CTI standards

    Multi-Vendor Integration Protocol (MVIP) System Computing System Architecture (SCSA) Both are buses connecting different PC cards Buses are used for call traffic within PC

    Petri Vuorimaa 51

    PC cards

    Petri Vuorimaa 52

    CTI APIs

    Microsoft Telephony Application Programming Interface = TAPI (-93)+ Windows applications

    Novell Telephony Service API = TSAPI (-93)+ Novell servers

    IBM CTI API+ Switches and their interfaces

    Petri Vuorimaa 53

    CTI APIs (cont.)

    SCSA framework Sun Java Telephony API = JTAPI

    + Java-framework+ utilizes above mentioned API definitions