This vast amount of digital information requires huge bandwidth and means that the time it would take to transmit video images would be impractical for most applications. That’s where compression is crucial. When determining how video conferencing works, one of the most important elements is the compression ratio.

The higher the compression ratio, the more quickly the information is capable of being transmitted. In many cases, however, this also means some loss in clarity or audio/video quality. For instance, a compression ratio of 4:1 would be terribly slow but have a fantastic picture quality. But by the time it was transmitted, everyone at the other end would probably have left the room for a cup of coffee. Lossy compression discards unneeded or irrelevant sections of a signal in order to transmit only the essentials, speeding up the transmission time significantly but sometimes resulting in loss of quality.

Compression can either be intra-frame or inter-frame for material that is repetitive or redundant, such as that wall behind the conference participant. Since the wall remains static and never changes, this image is redundant and can be eliminated from transmissions to an extent with proper compression. Intra-frame compression assumes the redundancy will be present in parts of a frame that are close to each other. Inter-frame compression assumes that there is redundancy over time (i.e., like that wall). Either of these can achieve a fairly high degree of accuracy and reduce the bandwidth needed for transmittal of signals.

A newer version of compression/decompression is SightSpeed technology, developed by Cornell University. SightSpeed compresses only images considered essential and eliminating what is considered ‘filler,’ relying on the brain to fill in the decompression at the other end. Based on an artificial intelligence model, SightSpeed achieves compression of about 90:1, compared to the typical 15:1 for video conferencing.

Any video conferencing session you use will provide compression of the transmission signal. The key is determining the balance between speed and video picture quality that is right for your needs.

Point to point video conferencing

Point to point video conferencing is just what it sounds like – a link between two different points on the planet, or two different video conferencing terminals. It could be between an office in New York City and a conference room in Munich. Point to point video conferencing can easily be initiated by someone on one end contacting the other end as though making a standard telephone call. There are no special arrangements to be made other than knowing that the participants will be there.

Multipoint conferencing is more complex

Multipoint conferencing is more complicated because it has to coordinate several different locations simultaneously. Since you can’t be in direct contact with several places at once while they are all in contact with others, you need one source that will tie them all together. In video conferencing, this is called a multipoint bridge or multipoint conferencing unit (MCU).