What is two-way interactive videoconferencing (IVC)?
Videoconferencing technology allows people at two or more locations to see and hear each other at the same time. In addition, it is often possible to share computer applications such as Internet pages, library catalogs, documents, or software.

Placing a video call is a lot like placing a telephone call. After you connect, you see the other person in color video and may be able to transfer files or collaborate via options such as document sharing or white boarding. The video frame rate varies from 5-30 frames per second, depending on the connection, hardware and software.

from http://www.kn.pacbell.com/wired/vidconf/

What are the formats and protocols for videoconferencing?

There are mainly two formats for videoconferencing:

1. Point-to-Point: This conferencing with video and audio on the network between two sites where each site can have capabilities like document sharing, chatting, etc.
2. Multiple Point or Multisite: Multisite videoconferencing allows three or more participants to sit in a virtual conference room and communicate as is if they wee sitting right next to each other. Related to multisite videoconferencing is "bridging" where sites connect through a meeting point software that supports these capabilities. The Tandberg 880 MXP system can include this software, or ACELINK sites can connect through a local bridging device.

What are the basic components of a videoconferencing system?

The Main Camera

By nature of the general definition of videoconferencing, at least one video source is typically present at each endpoint. The most common video source is a single main camera that captures live movement occurring at one end so that it may be sent to the other end in near real-time.

The Video Display

In addition to capturing local video, a videoconferencing solution must include the ability to display the remote video that is being received. This incoming video is displayed on a monitor, most often a television monitor or LCD projector with screen.

Audio Components

Within a videoconference audio is as important, and often considered more important, than video. For room videoconferencing, a high quality omni-directional microphone is included with the CODEC unit, or several smaller directional microphones are placed throughout the room. In all situations, it is important to avoid placing a microphone in the active range of a speaker. This can cause an echo effect which is very distracting and difficult to counterbalance. For a classroom setting, the speakers of a TV monitor can be used. For even larger rooms a separate sound system might be required comprising an amplifier, an optional equalizer and speakers.

The Codec

The codec has been mentioned above as affecting both the video and audio within a videoconference. Indeed, the codec actually forms the heart of any videoconferencing terminal. The word "codec" is a shortened version of "COmpressor/DE-Compressor" and is specifically applied to the wide variety of algorithms used for actually compressing or decompressing audio and/or video information. The codec is responsible for whatever compression/decompression of the audio/video signals is taking place. The processes of compression and decompression are also referred to as encoding and decoding respectively.

The User Interface

All systems that are meant for use have a user interface. These features may determine how we get into and out of conferences, what we can do in conjunction with a videoconference, and even what we know about how the call is going or what we have documented about the call once it's over. A typical school system includes a remote control that provides easy access to all system controls.

Videoconferencing system categories — putting everything together

Looking at current videoconferencing systems, and how the vendors implement all the above, can be useful to divide systems into 4 broad categories:

1. Software only codecs (personal use)
   These are the simplest systems. They frequently work with any webcam and a headset, and are very fast to set up. They provide adequate quality and ease of use for many applications of personal videconferencing.
2. Desktop/Laptop USB or PCI hardware codecs (business use)
   These are the next step up in quality and price. They include special hardware to assist the encoding of the audio and video signals, but the decoding is still done by the computer.
3. Set-top devices (most common for K12 schools)
   As the name implies, these are meant to be installed on top of a TV set. They are very easy to install, operate, maintain and support. These usually offer a lot of options for connecting other audio and video devices for input or output, and are often the preferred choice for setting up a videoconference room due to their mix of portability, quality, and price. Example: Polycom Viewstation, Tandberg 880 MXP.
4. PC-based integrated codecs (common in university or business settings)
   These are a combination of the previous two. They are usually an industrial grade computer with specialized hardware cards which offer a lot of connectivity options like the set-top category, but still can run PC applications like the desktop category. They are very useful when group videoconferencing is combined with collaboration applications.