Since 1995 when we started this site, videoconferencing has really taken off. There are now extensive networks of users, content providers, and support teams that didn't exist even two decades ago. Equipment has become easier to hook-up and use, protocol and network choices for transmitting the videoconference have expanded; and, for the most part; have become inter-operable. This page describes the types of videoconferencing systems in general use, basic equipment components and connections.

See our videconferencing links for related resources, including room setup and presentation techniques, who's doing what, distance learning, links to newsgroups, listservs, and more.

Examples | Instructional Strategies |
Multipoint | Compressed Video | Equipment |
Communication Skills | Planning | Evaluating

Initially, room-size videoconferencing was the only method of delivery. This was usually done on a unit which had a TV monitor, an entire computer or some large "box" devoted to coding and decoding the video transmission, and another box on top that held the camera. These systems were often cumbersome, required multiple steps to make the call, involved diagnostic tasks such as resetting echo cancellers, and were difficult to upgrade. In addition, the cost of ISDN was prohibitive and instability of ISDN connections made it frustrating for many users. As if that weren't enough, not all systems were compatible. Proprietary software made it difficult if not impossible for equipment from one vendor to communicate with equipment from another. A lot of folks simply shoved their units into a closet and that was that!

Over the years, prices have fallen, connections have stabilized, and setting up and using the equipment is easier than setting up your home DVR, DVD, or Blu-ray system. High Speed Internet connections have replaced most ISDN and discount programs like E-rate have considerably reduced the price of high speed networks for schools and libraries, and some equipment is e-rate eligible (always check the SLD Eligibility List first). As usage increased, videoconferencing systems evolved into three more or less distinct types: Integrated or Fixed (formerly called "room-size"), Portable, and Desktop.

Integrated systems: Room-size setups grew in complexity to meet the needs of teachers and students to the point where the equipment became integrated and physically fixed into the classroom design. In the integrated videoconferencing classroom, the teacher usually has access to a variety of multimedia equipment and peripherals right at their fingertips. Multiple monitors or large screens are used to display the video. Multiple microphones are available, and in some cases, each student has a microphone in front of them attached to the desk. In this environment, a lecturer presents from a high-tech classroom to students attending both locally and remotely. These videoconferencing systems typically use high quality audio-visual components, sophisticated codecs, and feature-rich control devices to create an experience suitable for a room full of participants. This mode is characterized by: one to many interaction controlled by the teacher or chair distinct and unequal participation more formal communication.

Portable units: Portables are great for almost any size group or classrooms. All of the equipment is loaded onto a rolling cart and moved to whichever location needs it. While it is extremely flexible, it also means someone has to hook it all up every time it is moved. In addition, adding more equipment such as multiple monitors, microphones, and other peripherals, becomes even more problematic. If a teacher won't do it or a tech support person isn't available, then most likely the videoconference will be limited to whatever equipment is on the cart. That is not to say the videoconference quality won't be as good as the integrated system; only that it will require a little more setup and testing. Mobility may be an advantage in some settings, especially if you don't have the space and money for a full-featured integrated system. These units are suitable for either formal or informat settings.

Desktop or Mobile: Advances in technology and the increasing availability of fast ethernet have transformed "Desktop" videoconferencing into one-on-one or man-to-many video communication all over the world. Voice over IP systems, such as Skype have turned any IP connected device with a camera and microphone into individual videoconferencing stations. Most laptops have a built-in camera. Many also have a built-in microphone. And most video tablets, such as the iPad, come with both. Add to this convenience a cloud or other document sharing feature, and participants can even see and edit a file while they are conferencing. Document sharing and the relatively low cost of desktop systems make this an ideal tool for tutoring, just-in-time learning, and short meetings. Some participants, on 4G networks, can participate by mobile phone. Desktop or Mobile videoconferencing is most often characterized by: one to one interaction equal participation relaxed method of control informal communication among participants

Basic Equipment Components
Codec: In simple terms, a codec is any technology for compressing and decompressing data. Codecs can be implemented in software, hardware, or a combination of both.The codec takes the analog video signal and codes (digitizes and compresses) it. The codec also has to decode (decompress and un-digitize) the received transmission. You can imagine that this kind of processing can take its toll on the video and sound quality. The most obvious consequence of a slow codec or low-bandwidth connection is a "jerky" picture and an audio time delay. We discuss how to deal with compressed video features in our Working With Compressed Video section. For more technical information about codecs, try the Wikipedia entry, video codec.

Monitor: Desktop systems display video in a small window on the computer monitor much like the movies and other media that we are used to playing on our computers. Portable and fixed systems have one or two large TV monitors. The two monitor setup allows display of the local audience in one and the remote in another. In conference-type settings, large movie or presentation screens can be used and the video is projected onto the screen. Strings of monitors are also used in large group settings.

Camera: The camera can be anything from a tiny desktop camera that attaches to the top of a computer monitor, is built in to the monitor, or it can be a high-quality model with remote control pan and zoom features (room system). High-end systems often come with a variety of input sockets allowing for connections to other peripherals such as a document camera, a second video input connection, and other auxilary equipment. When you expect to do a question and answer session, using two cameras is especially desirable. That way, the facilitator or main speaker has one dedicated camera and another can be used to pan the audience or pull in tight on a person asking a question. The second camera doesn't even need to be fully functional -- all it has to do is pass the input to the system!

Audio: Most high-quality systems come with a microphone designed for use with a small group of people. In many cases, an additional microphone can be connected as well, making your setup more versitile for larger groups or to add mobility. Most systems offer sophisticated dianostics and processing as a built-in feature to cancel out background noise and echo.

Control: Controls allow users to place calls, adjust volume, and sometimes even pan and zoom the camera. Desktop systems display controls and tools on the computer monitor window. Room systems come with remote control or console devices. (Early VTel controls shown) Click on these images to enlarge them ==>

More information about choosing equipment can be found at on our Videoconferencing Links page or see ViDe Videoconferencing Cookbook - Basic Requirements.

Connecting
The most significant distinction among videoconferencing systems has to do with how data is transmitted. Transmission is important not only because it impacts audio and video quality, but also because it limits connection options. In the early days, many systems were proprietary meaning they could only connect with their own systems using their own standard. Now, most systems are standards-based which means they can connect with any equipment using the same standard. Some popular standards are H.320 (ISDN) and H.323 (IP); however H.350, is on the rise. H.350 defines a service architecture for multimedia conferencing that includes H.323, H.320, SIP and generic protocols. For more on this new standard, see the H.350 page developed by the Video Middleware working group.

For many years, ISDN technology was the most widely used connection for high quality videoconferencing. ISDN connects through the existing phone infrastructure and provides a direct point to point connection at guaranteed bandwidth(s). This is still, in many ways, the most stable way to videoconference and continues to be used by many content providers as their first choice for connecting. However, IP video is rapidly becoming the choice, especially in the K-12 space, because of lower costs.

In the past, many viewed IP-based videoconferencing as a technology for the future because of the large use of bandwidth on the network. IP videoconferencing is finally beginning to emerge as a stable and cost effective solution as many schools and districts have substantially increased their network bandwidth. Since the platform uses an internet protocol, no special types of connections are needed beyond the existing network connection to the Internet; though for best results it is highly recommended that special hardware/software is installed to help strengthen the connection and guarantee quality.

Predictions are that videoconferencing will completely migrate to IP before too long. Many videoconference units can provide support for multiple platforms which further facilitates the migration from ISDN to IP.

Some additional connection considerations:

Gateways allow different conferencing protocols to connect to each other by receiving and translating data. For example, an Internet-based H.323 system won't be able to connect with an ISDN-based H.320 system without a some sort of gateway to translate. Users dial into the gateway and the gateway then passes them to the correct videoconference call. Many systems have an gateway adaptor built-in. Large entities, like corporations and school districts, might have a dedicated gateway server that handles all calls. Regular phone calls over POTS (plain old telephone system) can be added to the call as well! The POTS user can hear the videoconference and can interact with others in the conference. The gateway can even connect to a telephone bridge which enables participation by a large number of audio only users.

A gatekeeper is special sofware that runs on a computer or dedicated server and manages the activities of multiple conferences. For example, a gatekeeper will route calls for cost effectiveness, can switch to ISDN automatically if an IP address is unavailable, and maintains network contention to a miniumum.

An MCU or multipoint control unit enables multiple sites to participate in a videoconference. Many systems now have built-in MCU's which means you don't have to go through a special bridging service.

If these features are important to you now or you think you want a piece of equipment that will allow you to grow, make sure you carefully select your equipment so that these features can be added or are included. Here's a good picture of all of these components rack mounted and ready for use.