Video Conferencing Systems > Hardware

Video conferencing is a powerful tool and provides a virtual meeting environment that gives the benefit of real meeting.

There are various kinds of conferences held using a video conferencing information system.
Depending on the nature of the conference it becomes important to plan the video conferencing information system schedule. It becomes very important to check the requirements for smooth progress of the meeting. Back when video conferencing was a new trend, the quality and consistency of the feed was generally less than perfect.

However, videoconferencing future is very bright.


HARDWARE

The following section includes additional notes relating to the main types of video conferencing system.


Low-cost, Computer-based Systems

Low-cost systems are based on standard computer hardware. This type of system needs a fullduplex sound card, a headset, a web-cam (usually connected via a USB port) and suitable software. If used with a group, multiple headsets can be used via a splitter unit, enabling more than one user to conference.

PCs have had NetMeeting included with MS Windows for some years. The recently launched XP version of Windows is supplied with Windows Messenger as well as NetMeeting.

Apple Mac computers can run a range of software. Some Mac packages, such as VideoLink Pro, are compliant with video conferencing standards, while others, such as CUseeMe, require the same software running on near and far-end systems.
These systems are suitable for IP based video conferencing across local and wide area networks or via a dialup connection. It is not possible for such a system to call an ISDN based video conferencing system.

Note:
there is a distinction to be drawn between a dedicated or group-based video
conferencing system which is connected to the ISDN network, communicating using H.320 conferencing protocols, and an IP based H.323system which uses ISDN to dial into a network).

Applications and whiteboards can be shared whilst in a conference according to the facilities available within the software. The bandwidth available for the link may restrict or slow down application sharing. See Application and File Sharing for more details.


Desktop Systems

A number of manufacturers market units that can provide a better conferencing experience due to the use of better quality cameras and, in particular, better control over the audio.

Many units plug into the computer via a USB interface; others have to be installed into the computer. The majority of systems support IP conferencing; a smaller number support ISDN based conferencing.

These systems will use either Microsoft NetMeeting or proprietary software. Most systems of this type are standards compliant.


Group Systems

There is a very wide range of group systems available. Units in this category are often sold with a number of options, e.g. support for ISDN, IP or both, choice of the number of ISDN lines supported or choice of microphones. These choices can result in a wide variation in cost.


When choosing a system the following should be considered:

• Number of ISDN lines supported
• IP bandwidth supported
• Type of microphone supported. For example, some include microphones within the base unit; others use remote/table-top microphones
• Range of connections for connecting peripherals such as document cameras, VCRs or
  Laptops
• Quality of the audio and video compression systems
• Ability of the audio system to discriminate between voices and background sounds.
• Ability of the audio system to detect the location of the person speaking and move the
  camera to that person.
• Ability to give the user easy control of sources, e.g. cameras, laptops, VCR inputs etc.
• Easy to use user interface
• Support for multiple monitors to show near-end, far-end or source such as a laptop Group systems, including the monitors, can be built into roll-about cabinets, or may simply be small set-top units that can be used in a number of locations. However, so-called, roll-about systems are often only used in a dedicated video conferencing room or studio.

Audio control on desktop and group systems

Modern video conference systems use autogain control of the audio input in conjunction with the echo cancelling electronics to minimise the effect of big variations in sound level. In an interactive session it is far better to have all the participants, if they are all contributing to the meeting, to be sited at an equal distance from the microphone. The audio input will ‘hear’ equal sound pressure levels and adjust the audio input level [and thus the audio the far-end hears] to a ‘standard’ level to maintain the echo cancellation performance.

If a speaker gets close to the microphone it won’t matter how loud he speaks, the autogain control system will actually reduce the input audio level to the ‘standard’ level. If another speaker, further away, now speaks, the system will not have time to adjust the input level for a short period and the second speaker appears to be very quiet. This is a very common problem for new users of video conferencing and is often characterised by the new user speaking ‘at’ the microphone in an attempt to ensure the far end can hear correctly. It is also important to ensure there is reasonable distance between the microphone and the speakers. Usually this is three to five metres for group systems.
This helps the echo canceller.