Videoconferencing may not be that widespread now, but at some point in the future it will probably be as common as using the telephone or sending an e-mail. The main factors that will make it a sure hit are the growth of technologies with greater bandwidth such as ADSL and fiber optics, the spread of computers and Internet in households and the declining cost of the equipment needed to stage a videoconference, especially digital cameras.

How it works
During a videoconference session, images, sound and data are shared simultaneously and in an interactive fashion. Because so much information is contained in the video signal, one needs a bandwidth capable of sending a lot of information.

In any case, the videoconference uses video compression techniques. The device which carries this out is called the CODEC, for coder-decoder. It compresses the picture and sound so that it takes up little space during transport, and restores them at the receiver end with no loss of quality.

The quality of a videoconference is measured by the number of frames per second that the CODEC and network are able to handle. Minimal quality requires about 10 frames per second, but this can go even lower if the conventional telephone network is being used. But in the case of more sophisticated networks such as RDSI, ADSL or fiber optics, the number can go well over 30 frames per second.

Other parameters used to measure the quality of a videoconference are the audibility of the conversation, the level of background noise and absence of echoes. Other useful features include are automatic pinpointing of the person who is speaking, which averts the need to have someone keep track of this or project a standard, group-style picture. And above all, in the business world, it is important to have a catalogue of group working tools such as interactive electronic blackboards and shared data files.

There are basically three kinds of system available on the market. High-range ones are composed of systems for large gatherings such as conferences and seminars; others based on PCs, for group videoconferences, and finally desktop systems for individual communications. The first two are used at public meetings and in business, while the third, also known as personal videoconferencing, is for home users.

The secret of this third group lies in harnessing the power and multimedia features of today's computers. The equipment comprises a full duplex sound card which allows you to play and record at the same time, a microphone, a camera mounted on the computer console and communications software, which is usually Microsoft NetMeeting. The latter is distributed for free. The video image shows up on the PC screen inside a window, and the size depends on the capacity of the network, although it is usually about a quarter of the size of the screen.

A critical element is the web camera. It is composed of a lense the focuses the image on the matrix of the CCD (the device that captures images from outside), a light and color processor that handles the electrical signal that comes from the CCD and another processor that places each point of the image on the computer screen.

In choosing a web camera, an important consideration is the resolution because it will determine the picture quality during a videoconference. The minimum to be demanded of a web camera is 24 bits of color and a resolution of 352 X 288 pixels at a speed of 15 frames per second, and 160 X 120 pixels at 30 fps.

There are a variety of models available, designed to suit different needs and budgets. Companies such as Canon, Kodak, Philips, Creative Labs, Logitech, Sony, Suvil, Best Buy, Avermedia, Terratec and Zoltrix are among the manufacturers of these essential devices that make videoconferences a reality.
�����