The Basics of Video Conferencing

Video conferencing hardware and software allows users to see and hear the person they are communicating with, which certainly has bonuses over conference calls and e-mail. Large corporations are using this method more and more frequently to allow their associates maximum convenience and more effective communication.

A video conference allows you to take part in live audio/video presentations in your classroom, and to collaborate through them. Calls can be made between 2 classrooms in the same town, or between 2 classrooms in different parts of the globe. It is also possible for multipoint conferences to take place, where more than 2 schools take part in the same call.

Live video conferences have lots of advantages over other multimedia resources, such as video recordings or television presentations, but the main benefit is that they are interactive, allowing you to talk face to face with someone else in 'real time', but in a different location. This is great for for gaining high levels of engagement from your students.

Multipoint videoconferencing

Simultaneous videoconferencing among three or more remote points is possible by means of a Multipoint Control Unit (MCU). This is a bridge that interconnects calls from several sources (in a similar way to the well-known audio conference call). All parties call the network ID number of the MCU unit or the MCU unit can also call the parties which are going to participate, in sequence. There are MCU bridges for IP and ISDN-based videoconferencing. There are MCU which are pure software, and others which are a combination of hardware and software. A MCU is characterised according to the number of simultaneous calls it can handle.

MCUs can be stand-alone hardware devices, or they can be embedded into dedicated TVC units.

The technology of video conferencing

The core technology using in a videoteleconference (VTC) system is in digital compression of audio and video streams in real time.

There are basically two kinds of VTC systems:

Dedicated systems have all required components packaged into a single equipment, usually a console with a high quality remote controlled video camera on its top. These cameras can be controlled at a distance to move in the horizontal and vertical directions (pan and tilt, respectively) as well as to perform image zooming, so they are called PTZ cameras. The console contains all electrical interfaces, the control computer, modem, and the software- or hardware-based codec. Omnidirectional microphones are connected to the console, as well as a monitor TV with loudspeakers and/or a video projector. There are several types of dedicated VTC devices:

(a)Large group VTC are non-portable, large, more expensive devices used for large rooms and auditoriums. Use of PTZ cameras is practically mandatory.

(b)Small group VTC are non-portable or portable, smaller, less expensive devices used for small meeeting rooms (e.g., up to 10 people) and PTZ cameras are usual

(c)Individual VTC are usually portable devices, meant for single users, have fixed cameras, microphones and loudspeakers integrated into the console.

Desktop systems are add-ons (hardware boards, usually) to normal PC's, transforming them into VTC devices. A range of different cameras and microphones can be used with the board, which contains the necessary codec and transmission interfaces. Most of the desktops systems work only with the H.323 standard. Video conferences carried out via dispersed PCs are also known as e-meetings.