A
AES: Advanced Encryption Standard. The highest level of embedded encryption security for videoconferencing. Security comes from the key, a number which is passed to the algorithm to tell it how to encrypt the data. A commonly employed communications encryption method is DES.
Algorithm: A step-by-step problem-solving procedure. Transmission of compressed video over a communications network requires sophisticated compression algorithms. Some videoconferencing systems offer both proprietary and standard compression algorithms.
Analog Gateway: A means of connecting dissimilar codecs. Incoming digital signal from one type of codec is decoded by a similar codec and converted to analog. The Analog signal is then passed to the dissimilar codec, coded, and decoded at the far end. Analog gateways achieved interoperability in a nonstandard environment, but have the disadvantages of degrading video and audio quality and often reducing functionality.
Analog Signals: Audio/video signals currently used in broadcasting where the signal is represented by variable measurable physical quantities (such as voltage). Current TV and radio signals are analog, as are many telephone lines. (Contrast with digital). Example devices: video camera, VCR, projector, scan converter, document camera, sound system.
Annex D Graphics: An addendum to the H.320 videoconferencing protocol used for still image transfer between dissimilar videoconferencing systems.
Aspect Ratio: The ratio of a picture’s width to height. In video, this ratio is four units wide by three units high or 4:3. Widescreen, or 16:9 aspect ratio, is becoming more ubiquitous with the introduction of flat-panel displays (e.g. plasma, LCD) and HD videoconferencing.
Asynchronous: Communication in which interaction between parties does not take place simultaneously.
Asynchronous Transfer Mode (ATM): A method of sending data in irregular time intervals using a code such as ASCII. ATM allows most modern computers to communicate with one another.
ATM: Asynchronous Transfer Mode. An emerging networking method that can be used for carrying voice, video and data simultaneously over low speed (T1 - 1.5 Mbps) or very high speed (622 Mbps) networks.
Audio: In video communications, electrical signals that carry sounds. The term is also used to describe systems concerned with sound with recording and transmission; speech pickup systems, transmission links that carry sounds, amplifiers and the like. Example devices: microphones, audio mixer.
Audio Add-On: Allows a participant to join a videoconference via audio (telephone) only. This can be done through one of the codecs or through the video bridge.
Audio Bridge: Equipment that mixes multiple audio inputs and feeds back composite audio to each station after removing the individual station's input.
Audio Conferencing: Voice only connection of more than two sites using standard telephone lines.
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B
B Channel: The ISDN circuit-switched bearer channels, capable of transmitting 64 Kbps of digitized information.
Backbone: A primary communication path connecting multiple users.
Band: A range of frequencies between defined upper and lower limits.
Bandwidth: In casual use, the amount of information that can be transmitted in an information channel. High bandwidth internet access means web graphics load quickly on Netscape. High bandwidth videoconferencing means that the picture and sound will be clear. In computers, the speed at which data can be transmitted on a communications frequency. In telecommunications, the maximum frequency (spectrum) measured in Hertz or cycles per second, between the two limiting frequencies of a channel. In terms of videoconferencing (using IP or ISDN networks), the speeds or bandwidths usually run in increments of 64Kbps.
Basic Rate Interface (BRI): An ISDN access or subscriber line, consisting of two 64Kbps B ("bearer") channels and one 16Kbps D channel used for both data and signaling purposes.
Bit: Abbreviation for a single binary digit. The smallest unit of information with two possible states, (e.g. one or zero, on or off, yes or no).
Bit Rate: The speed of a digital transmission, measured in bits per second.
bps: Bits per second, a unit of measurement of the speed of data transmission and thus of bandwidth (lower case is significant).
Bps or BPS: (8-bit) bytes per second (upper case is significant).
Bridge: In videoconferencing vernacular, a bridge connects three or more conference sites so that they can simultaneously communicate. Bridges are often called MCU's - multipoint conferencing units. In IEEE 802 parlance, a bridge is a device that interconnects LAN's or LAN segments at the data-link layer of the OSI model to extend the LAN environment physically. They work with frames (as opposed to packets) of data, forwarding them between networks. They learn station addresses and they resolve problems with loops in the topology by participating in the spanning tree algorithm. Finally, the term bridge can be used in audio conferencing to refer to a device that connects multiple (more than two) voice calls so that all participants can hear and be heard.
Broadband: The term applied to networks having bandwidths significantly greater than that found in telephony networks. Broadband systems are capable of carrying a large number of moving images or a vast quantity of data simultaneously. Broadband techniques usually depend on coaxial or optical cable. Contrast with wideband and narrowband.
Broadcast: One-way video, usually from a single transmitting site to many receiving sites. In some cases, the receiving sites can communicate to the transmitting site on an audio-only basis.
Browser: Software that allows you to find and see information on the Internet.
Byte: A single computer word, generally eight bits.
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C
Cable Modem: A device that connects a computer to the Internet through a Cable TV coaxial cable. Cable modems are considered to be a high bandwidth, or high speed connection.
Camera Presets: Allows pre-defined camera angles to be programmed into a videoconferencing system.
Carrier: A term used to refer to various telephone companies that provide local, long distance or value added services; alternately, a system or systems whereby many channels of electrical information can be carried over a single transmission path. Example carriers: AT&T, MCI, Sprint.
CCITT: International Telephone and Telegraph Consultative Committee. Now known as ITU-T. An international body that sets worldwide telecommunications standards, such as the Px64 standard for videoconferencing.
Channel: The smallest subdivision of a circuit, usually with a path in only one direction.
Channel Bank: Used to divide a T1 access facility into 24 digital or analog circuits.
Channel Service Unit (CSU): A type of customer premise equipment that terminates a T1 access facility to a channel bank, PBX or other equipment capable of supporting a T1 interface.
Codec: Coder-Decoder. Videoconferencing hardware that codes the outgoing video and audio signals and decodes the incoming signals. Prior to transmission, the codec converts analog-signals to digital signals and compresses the digital signals. Incoming audio and video must be decompressed and converted from digital back to analog.
Compressed Video: When the vast amount of information in a normal TV transmission (90 Mbps) is squeezed into a fraction of its former bandwidth by a codec, the resulting compressed video can be transmitted more economically over a smaller carrier (ISDN). Some information is sacrificed in the process, which may result in diminished picture and sound quality.
Compression: Reduction of the amount of information to accommodate cost-effective digital transmission to another codec. For example, sub-T1 video codecs compress analog signals (roughly equivalent to 90,000 kilobits per second) to digital rates varying from 56 to 1,544 kilobits per second.
Compression Ratio: A compression ratio, usually expressed as 5:1, refers to the size of the original data versus the size after compression. If data has been reduced to one-fifth the original size, the compression ratio is 5:1.
Continuous Presence: Conference allowing each site to view other sites on a screen. Sites can be viewed in multiple configurations of a split screen.
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D
D-Channel: The Delta (“D”) channel can be either a 16 kbps or 64 kbps channel used primarily for communications (or “signaling”) between switching equipment in the ISDN network and the ISDN equipment at your site.
Data Rate: The measurement for bandwidth in bits per second. In general, the higher the data rate, the higher the quality of video.
Dedicated Line: A permanently assigned path connecting geographically dispersed sites on a long distance network. Synonym: private line: leased line.
Delay: Refers to the slight delay that sometimes occurs when transferring video, data and audio signals.
Demarc (Demarcation): the location in a facility where the network service provider supplies the point of connectivity for internal writing and the end user equipment.
DES (Data Encryption Standard): DES works by encrypting data with a 56-bit long key. Triple DES (3DES) is an enhancement to DES that effectively runs 112-bit long keys. DES and 3DES are both widely used in commercial and non-defense government communications today.
Desktop Videoconferencing: Video conferencing on a personal computer. Most appropriate for small groups or individuals (compare with room-based videoconferencing). Many desktop videoconferencing systems support document sharing.
Dif Serv (Differentiated Services): Marks IP packets for routers and switches to help prioritize traffic flowing through a network.
Digital: Conversion of information into bits of data for transmission through wire, fiber optic cable, videoconference, or over air techniques. Method allows simultaneous transmission of voice, data, and video.
Digital Service Unit (DSU): A type of customer premises equipment that terminates a single DSO or fractional T1.
Digital Signals: Audio/video signals represented by discrete variations (in voltage, frequency, amplitude, location, etc.). A digital clock, for example, displays the time as discrete numeric values rather than angular displacement of analog hands. In general, digital signals can be transmitted faster and more accurately than analog signals. As an example, music from digital cd's is usually more clear than music from analog records. (Contrast with analog signals.)
Digital Switch: A means of supporting multiway conferencing using the signals in their digital format without converting them to analog. Digital switches permit multiple users with similar codecs to conference generally with voice-activated switching.
Distance Education: The process of providing instruction when students and instructors are separated by physical distance, and technology, often in tandem with face to face communication.
Distance Learning: The incorporation of video and audio technologies into the educational process so that students can attend classes and training sessions in a location distant from that where the course is being presented. Distance learning systems are usually interactive and becoming a highly valuable tool in the delivery of education to widely dispersed students.
Document Camera: The distance learning equivalent of an overhead projector. Images of two or three dimensional objects using either top or base lighting can be transmitted to remote sites when this video source is selected.
Document Sharing: A feature supported by many desktop videoconferencing systems that allows participants at both ends of a videoconference to view and edit the same computer document.
DSO: Digital Signal level zero. One 56Kbps (or 64Kbps) line or circuit.
DS1: Digital Signal level one. One 1.544Mbps digital signal comprised of 24 lines or channels, each with 64 Kbps capacity (see T1).
DSL: Digital Subscriber Line. Refers to high speed Internet connections obtained through a special service of the phone company, using their standard telephone line.
Dual 56: Combination of two 56Kbps lines for a 112Kbps video transmission capacity. Dual 56 typically allows direct dialing of a videoconference call.
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E
E1: High speed 2.048Mbps digital line with 32 channels, each operating at 64 Kbps. E1 is only available outside the U.S.A.
Echo Cancellation: Process of eliminating acoustic echo in a videoconferencing room.
Encryption: Alteration of transmitting information to protect it from unauthorized tapping. Embedded encryption allows you to enjoy the full array of features without any degradation in performance, unlike third-party, non-embedded encryption solutions. All encryption methods use common algorithms.
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F
Facilitator: The individual at a remote location responsible for performing assigned tasks designated by the instructor.
FCIF/QCIF: Standards-based formats for communicating between videoconferencing systems from different vendors. QCIF is one quarter of the resolution of FCIF.
Fiber Optic Cable: Glass fiber that is used for laser transmission of video, audio and/or data.
Firewall: An application that isolates part of a network, like a company's private intranet, from access to or by other parts of the network, like the public Internet.
Flash Memory: Memory which occupies little space and does not need continuous power to be retained.
Fractional T1: Any data transmission rate between 56Kbps and 1.544 Mbps. It is typically provided by a carrier in lieu of a full T-1 connection to reduce costs for long distance videoconferencing.
F.R.A.D: Frame Relay Access Device: F.R.A.D. takes the information streams and multiplexes them on public or private frame relay networks.
Frame Rate: Frequency in which video frames are displayed on a monitor, typically described in frames-per-second (fps). Higher frame rates improve the appearance of video motion. Broadcast TV (full motion video) is 30 frames-per-second.
Frame Relay: A packet switched networking technology used for low speed (T1 - 1.5Mbps and lower) WAN connections. Primarily used to connect a company's routers on their data network.
Frames Per Second (fps): Frequency with which video frames appear on a monitor. Broadcast-quality video generally consists of 30 frames per second. Full-motion videoconferencing typically offers video in the range of 10 - 15 frames per second. At very low bandwidths, such as 56 or 112 Kbps, the frame rate may be lower.
Frequency: The space between waves in a signal. The amount of time between waves passing a stationary point.
Full Duplex Audio: Audio that allows local and remote conference participants to speak simultaneously without losing audio contact. Full-duplex audio may be provided in a point-to-point or multipoint conference.
Full-Motion Video: Video reproduction at 30 frames per second (fps) for NTSC signals or 25 fps for PAL signals. Also known as continuous-motion video. In the videoconferencing world, the term "full-motion video" is often used, and often misunderstood. Videoconferencing systems cannot provide 30 fps for all resolutions at all times nor is that rate always needed for a high-quality, satisfying video image. Picture quality must sometimes be sacrificed to achieve interactive visual communication across the telephone network economically. Videoconferencing vendors often use "full-motion video" to refer to any system that isn't still-frame. Most videoconferencing systems today run 10 to 15 frames per second at 112 Kbps. Need 384 Kbps in order to transmit 30 FPS.
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G
G.711: 3KHz audio-coding at 64Kbps.
G.722: 7KHz audio-coding at 64Kbps.
G.728: 3KHz audio compression at 16Kbps (wideband audio).
Gatekeeper: In H.323 IP telephony, a Gatekeeper is an optional server that is responsible for network-based services including a registration, admission, and status, for which it uses a special protocol called RAS. Gatekeeper functions include address translation, call authorization and bandwidth management, as well as providing accounting information.
Gateway: The original Internet term for what is now called a router or, more precisely, IP router. Refers to systems that translate from one native format to another.
Graphics: Transmission of still images, usually from a video source, but in some cases PC-generated.
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H
H.221: The ITU-T standard relating to communications protocol for videoconferencing.
H.230: The ITU-T standard that defines call control and indication.
H.231: Multipoint for linking three or more H.320 codecs.
H.233: Encryption.
H.242: Call set-up and disconnect of two point videoconferencing.
H.243: Defines call control procedures between H.231 MCU and H.320 codecs.
H.261: The ITU-T Px64 standard relating to the video compression algorithm.
H.320 Standard: A widely-used video compression standard that allows a wide variety of videoconferencing systems to communicate utilizing ISDN telephone lines.
H.323 Standard: Extends H.320 standard to Intranet, Extranet or Internet over packet-switched networks: Ethernet, Token-Ring, ATM and others. Also referred to as IP videoconferencing.
H.324: Video over POTS.
Half Duplex Audio: 2-way audio transmitted and received in turn (rather than simultaneously) so only one site can speak at a time. Contrast with full duplex audio.
HD: High Definition.
HDTV: High Definition Television. Term widely used in the use and broadcast method of flat-panel displays such as LCDs and plasma screens.
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I
In-Band: Transmission taking place within allocated bandwidth. For example, a video call with total of 384Kbps may allocate 64 Kbps for audio, leaving 320Kbps for video.
Instructional Television Fixed Service (ITFS): Microwave-based, high frequency television used in educational program delivery.
Integrated Presentation System: Presentations such as those created in Microsoft® PowerPoint®, can be displayed and presented to the far site while simultaneously being presented to remote users connected via the Internet/Intranet.
Intellectual Property: As it applies to distance learning, it is a question of ownership of a creative piece of work: the instructor, artist or institution.
Interactive: Communication in which all participating sites have equal capability. Interactive videoconferencing permits all sites to see and hear one another.
Internet: An international network of networks primarily used to connect education and research networks begun in the United States government. Internet Protocol (IP): the international standard for addressing and sending data via the Internet.
Interoperability: Communication between dissimilar codecs. The ITU-T Px64 standard is designed to permit interoperability.
Inverse Multiplexer (IMUX): Hardware that aggregates available ISDN lines together to achieve a required transmission rate. (Two channels – 128kbps, four channels – 256kbps, six channels – 384kbps).
IP (Internet Protocol): Packet-based protocol for delivering data across networks.
ISDN (Integrated Services Digital Network): ISDN is essentially a digital network that will provide seamless communications of voice, video, and text between individual desktop videoconferencing systems and group videoconferencing systems. ISDN is expected to replace current telephone lines. There are two major forms of ISDN: BRI and PRI.
ITU-T: International Telecommunications Union-Telephony Sector. Formerly known as CCITT. An international body that sets worldwide telecommunications standards, such as the Px64 standards for videoconferencing.
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J
JPEG: Joint Pictures Experts Group. Still-frame graphics for multimedia.
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K
Kbps: Kilobits per second. A unit of measurement to calculate the speed of transmission. The higher the Kbps or speed, the better the quality of the voice or video conference.
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L
LD: Long distance service.
LEC: Local Exchange Carrier; provides local telecommunications service and access to long distance networks.
Listserv: An e-mail program that allows multiple computer users to connect onto a single system, creating an on-line discussion.
Local Access and Transport Areas (LATA): The areas within which the Bell Operating and independent telephone companies can provide transport services. Inter-LATA connections must be provided by Inter-exchange or long-distance carriers.
Local Area Network (LAN): Two or more local computers that are physically connected.
Local Loop: The communications lines between the long distance subscriber and the LEC switching center.
Loopback: A diagnostic test where a signal is transmitted over a communications link or network and then returned to the sending device. Loopbacks are used to make sure the video equipment is working properly and as a way to demonstrate videoconferencing.
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M
Microwave: Electromagnetic waves that travel in a straight line and are used to and from satellites and for short distances (i.e., up to 30-40 miles).
Modem (Modulator/Demodulator): A piece of equipment to allow computers to
interact with each other via telephone lines by converting digital signals to analog for transmission over analog lines.
MPEG: Motion Pictures Experts Group: This is a standard for motion video.
MPLS: Multiprotocol Label Switching. MPLS is the most advanced mechanism used to control traffic routing and consistency of throughput within Service Provider backbone networks.
Multimedia: Any document which uses multiple forms of communication, such as text, audio, and/or video.
Multiplexer: A device that permits subdivision of a given bandwidth. For example, a T1 Multiplexer may divide a T1 line (1,544Kbps) into two capacities of 768Kbps each.
Multipoint Control Unit (MCU): Computerized switching system that allows videoconferencing between more than two points, and may support fifteen or more points in a simultaneous videoconference.
Multipoint Videoconference: Videoconference with more than two sites. The sites must connect via a video bridge. (Compare with point-to-point videoconference.)
Multiway: Communication between more than two sites. Multiway communication may occur through a digital switch or through an analog gateway.
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N
Narrowband: A low-capacity communications circuit/path. It usually implies a speed of 56Kbps or less. (Contrast with wideband and broadband)
Network: A system that transmits any combination of voice, video and/or data between users. The network includes the network operating system in the client and server machines, the cables connecting them and all supporting hardware in between such as bridges, routers and switches.
NT: Network Terminal.
NT-1: Network Termination type 1. The NT-1 is a device which converts the two-wire line (or "U" interface) coming from your telephone company into a 4-wire line (or "S/T" interface). The NT- 1 is physically connected between the ISDN board of your videoconferencing system and your ISDN phone line. The NT- 1 supports network maintenance functions such as loop testing. Check to see if your ISDN equipment requires an external NT-1 to operate.
NTSC (National Television Standards Committee): A video standard established by the United States (RCA/NBC} and adopted by numerous other countries. This is a 525-line video with 3.58-MHz chroma subcarrier and 60 cycles per second. Frames are displayed at 30 frames per second.
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O
On-Line: Active and prepared for operation. Also suggests access to a computer network.
Origination Site: The location from which a teleconference originates.
Out of Band: Transmission taking place external to allocated bandwidth. A video call with out-of-band audio requires a separate phone line for the audio.
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P
Px64: The ITU-T's international video standard which provides a standard algorithm for video compression and decompression. Formally known as H.261, it was adopted in December 1990.
Packet: A block of data used for transmission in packet-switched systems.
PAL (Phase Alternative Line System): The European TV standard based upon 50 cycles per second electrical system and 625 lines per frame and 25 Frames per Second. (NTSC, the North American standard is based on 30 frames per second) (French use SECAM)
Pixel: Picture element; a measure of resolution for video format.
Point of Presence (POP): Point of connection between an inter-exchange carrier and a local carrier to pass communications into the network.
Point-to-Multipoint: Transmission between multiple locations using a bridge.
Point-to-Point Videoconference: Videoconference between two sites. (Compare with multipoint videoconference.)
Primary Rate Interface (PRI): An ISDN subscriber line consisting of 23 64Kbps B channels and one 64Kbps D channel used for signaling.
Proprietary Compression Algorithm: A vendor-specific algorithm for compression of a video signal. A videoconferencing system using a proprietary algorithm can only communicate with a remote site using the same algorithm. Many vendors also adhere to standard compression algorithms to facilitate communication across platforms.
Protocol: A formal set of standards, rules, or formats for exchanging data that assures uniformity between computers and applications.
PSTN (or POTS): Public Switched Telephone Network. The collection of interconnected systems operated by the various telephone companies and administrations (telcos and PTTs) around the world. Also known as the Plain Old Telephone System (POTS) in contrast to VoIP and ISDN.
Public Network: A telecommunications network designed for open, public access.
Public Room: Videoconferencing service offered to the public on a fee-for-usage basis.
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Q
QCIF: Quarter Common Intermediate Format. A video resolution of ¼ the size of FCIF - 176 pixels horizontally and 144 pixels vertically. It is used primarily ion low bite rate (128Kbps and lower) videoconferencing.
QoS: Quality of Service. The ability to define a level of performance in a data communications system. For example, the ATM networks specify modes of service that ensure optimum performance for traffic such as real-time voice and video.
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R
RBOC: Regional Bell Operating Company; controls a grouping of local exchange carriers.
Real Time: The processing of information that returns a result so rapidly that the interaction appears to be instantaneous. Telephone calls and videoconferencing are examples of real-time applications.
Resolution: A measure of sharpness or clarity on a monitor.
Room-Based Videoconferencing: Videoconferencing using a sophisticated system is appropriate for large groups. (Compare to desktop videoconferencing.)
Room Coordinator: A room coordinator (room monitor) is there to make sure the equipment is on and operational, greet the incoming attendees and be nearby in case something is needed i.e. adjust the volume or troubleshoot. They are not necessarily present in the room during the actual videoconference.
Router: A device or setup that finds the best route between any two networks, even if there are several networks to traverse. Like bridges, remote sites cab be connected using routers over dedicated or switched lines to create WANs.
RS-232: Connectivity from the codec permitting data inputs for transmission from .3 to 190.2 Kbps.
RS-449: Transmission interface between the codec and the transmission link that typically connects to a t1 Multiplexer. A user RS-449 port may also be available for data transfer.
RSVP: Resource Reservation Protocol. An emerging data network standard protocol used to reserve bandwidth within packet networks. It is primarily used in data network routers to guarantee a fixed bandwidth through the router for a single or group of users using real time data (like voice or video). All other traffic not assigned to the reservation (such as e-mail or Web access) is delivered by best effort by the router (as it is today).
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S
Satellite TV: Video and audio signals are relayed via a communication device that orbits around the earth.
SECAM: French standard for analog video format.
SNMP: Simple Network Management Protocol; the protocol governing network management and monitoring of network devices and their functions. SNMP came out of the TCP/IP environment.
Speed Matching: Upgrades the speed of a lower channel codec to a higher channel conference.
Standard Compression Algorithm: An algorithm convention for compression of a video signal. Adherence to standards allows communication among a wide variety of videoconferencing systems, though not with the same clarity as two similar systems using a proprietary algorithm. H320 is the most widely accepted standard in use today.
Standards: Uniform specifications to permit interoperability in videoconferencing.
Switch: A mechanical or solid state device that opens and closes circuits, changes operating parameters or selects paths for circuits on a space or time division basis.
Switched 56: Transmission network at 56Kbps that allows dial-up videoconferencing. Because picture quality at 56Kbps is often not acceptable, most dial-up videoconferencing takes place on two 56Kbps lines, for a total of 112Kbps (see Dual 56).
Synchronous: Communication in which interaction is simultaneous.
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T
T1 (DS1): High-speed digital data channel that is a high volume carrier of voice and/or data. Often used for compressed video teleconferencing. T1 has 24 voice channels.
T3 (DS3): A digital channel that communicates at a significantly faster rate than T1.
T.120: Multilayer protocols for graphics/data transmission.
TCP/IP: The international standard protocol used on the Internet and company data networks. It provides worldwide connectivity and includes serves such as the World Wide Web, e-mail, file transfer and remote terminal login.
TELCO: Generic term for the local telephone company. Can refer to an inter-exchange carrier or to the Local Exchange Carrier.
Telecommunication: The science of information transport using wire, radio, optical, or electromagnetic channels to transmit/receive signals for voice or data communications using electrical means.
Teleconferencing: Two way electronic communications between two or more groups in separate locations via audio, video, and/or computer systems.
Transmission Control Protocol (TCP): A protocol that makes sure that packets of data are shipped and received in the intended order.
Transmission Speed: Data rate for videoconferencing, usually expressed in Kbps.
Transponder: Satellite transmitter and receiver that receive and amplify a signal prior to re-transmission to an earth station.
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U
Uniform Resource Locator (URL): The address of a homepage on the WWW.
Uplink: The communication link from the transmitting earth station to the satellite.
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V
V.35: Transmission interface between the codec and the transmission link that permits Switched 56 connectivity.
Video Bridge: Computerized switching system which allows multipoint videoconferencing.
Video Streaming: Streaming is a server/client technology that allows live or pre-recorded data to be broadcast in “real time,” opening up the network for traditional multimedia applications such as news, training, entertainment, advertising, and a host of other uses. Streaming enables the internet or company intranet to act as a broadcast medium for audio and video.
Video Teleconferencing: A teleconference including two way video.
Videoconferencing: Communication across long distances with video and audio contact that may also include graphics and data exchange.
Voice Activated Switching: In multiway videoconferencing, used so that all participating sites automatically see the site which is currently speaking.
Voice-Tracking: Camera automatically tracks the voice of the person speaking.
VoIP (Voice Over Internet Protocol or Voice Over IP): A protocol for transmitting the human voice in digital form over the internet or other networks as an audio stream, instead of using traditional telephone lines (PSTN or POTS). VoIP uses the Internet Protocol (IP), but is not limited to communication by computer – even phone-to-phone communication can be conducted using this technology.
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W
Web Browser: A software application used to locate and display Web pages. Three of the most popular browsers are Netscape Navigator, Microsoft Internet Explorer, and Spyglass Mosaic. All of these are graphical browsers, which means that they can display graphics as well as text. In addition, most modern browsers can present multimedia information, including sound and video.
Web Server: A computer that delivers (serves up) Web pages. Every Web server has an IP address and possibly a domain name. For example, if you enter the URL http://www.sandybay.com/ in your browser, this sends a request to the server whose domain name is sandybay.com. The server then fetches the page named and sends it to your browser.
Whiteboarding: A term used to describe the placement of shared documents on an on-screen "shared notebook" or "whiteboard." Desktop videoconferencing software includes "snapshot" tools that enable you to capture entire windows or portions of windows and place them on the whiteboard. You can also use familiar Windows operations (cut and paste) to put snapshots on the whiteboard. You work with familiar tools to mark up the electronic whiteboard much like you do with a traditional wall mounted board.
Wide Area Network (WAN): A communications network that services a geographic area larger than that served by a local area network or metropolitan area network.
Wideband: A medium-capacity communications circuit/path. It usually implies a speed from 64 Kbps to 1.544 Mbps. (Contrast with broadband and narrowband)
World Wide Web (WWW): A graphical hypertext-based Internet tool that provides access to homepages created by individuals, businesses, and other organizations.
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