A guide to Videoconferencing

AKA Videoconference - videoteleconference - visual collaboration

High tech - issues - issue

A videoconference is a set of interactive telecommunication technologies which allow two or more locations to interact via two-way video and audio transmissions simultaneously. It is a type of groupware. It differs from videophone in it is designed to serve a conference rather than individuals.

Videoconferencing can enable individuals in faraway places to have meetings on short notice.

The core technology used in a videoteleconference (VTC) system is digital compression of audio and video streams in real time. The hardware or software to performs compression is called a codec (AKA coder / decoder). Compression rates of up to 1:500 can be achieved. The resulting digital stream of 1's and 0's is subdivided into labelled packets, are then transmitted through a digital network of some kind (usually ISDN or IP). The use of audio modems in the transmission line allow for the use of POTS, or the Plain Old Telephone System, in some low-speed applications, such as videotelephony, because they convert the digital pulses to / from analog waves in an audio spectrum range.

The other components required for a VTC system include:

Video input : video camera or webcam
Video output: computer monitor , television or projector
Audio input: microphones
Audio output: usually loudspeakers associated with the display device or telephone
Data transfer: analog or digital telephone network, LAN or Internet
two kinds of VTC systems:

A video teleconferencing unit (VTU) is a piece of electrical equipment to performs video teleconference functions, such as coding and decoding of audio and video signals and multiplexing of video, audio, data, and control signals, and that usually does not include I/O devices, cryptographic devices, network interface equipment, network connections, or the communications network to which the unit is connected.

The virtual press conference is much like a news conference. It is a conference where the speaker is sitting in a chair in a studio for example whilst the video and audio are relayed via satellite to another location.

Telecommunication, teleconference is the live exchange and mass articulation of information among persons and machines remote from one another but linked by a telecommunications system, usually over the phone line.

Internet telephony involves conducting a teleconference over the the Internet or a Wide Area Network. One key technology in this area is Voice over Internet Protocol (VOIP). Popular software for personal use includes Skype, Google Talk, Windows Live Messenger and Yahoo Messenger.

Simultaneous videoconferencing among three or more remote points is possible by means of a Multipoint Control Unit (MCU).

A fundamental feature of professional VTC systems is acoustic echo cancellation (AEC). AEC is an algorithm which is able to detect when sounds or utterences reenter the audio input of the VTC codec, which came from the audio output of the same system, after some time delay.

medicine and health

Rural areas can use this technology for diagnostic purposes, thus saving lives and making more efficient use of health care money.

education

Whiteboarding is a term used to describe the placement of shared files on an on-screen "shared notebook" or "whiteboard". Videoconferencing software such as TalkAndWrite, Groupboard, Windows Live Messenger, and BitWise IM include tools that let the user mark up the electronic whiteboard much as one would with a traditional wall-mounted board.

Real-time Virtual field trips involve the use of videoconferencing and audioconferencing technologies to permit students in one location to virtually visit and learn about people or places in another location.

A videophone is a telephone which is capable of both audio and video duplex transmission. It differs from videoconferencing in that it expects to serve individuals, not groups.

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