The simplest definition of how video conferencing works is simply by the integration of video, audio and peripherals to enable two or more people to communicate simultaneously over some type of telecommunications lines. In other words, you are transmitting synchronized images and verbal communications between two or more locations in lieu of them being in the same room. How video conferencing works is a little bit harder to explain than answering the question, "What is video conferencing?"
Millions of people use video conferencing every day around the globe, but very few people know just how the technical aspects of the process work. The main ingredients of successful video conferencing are video cameras, microphones, appropriate computer software and computer equipment and peripherals that will integrate with the transmission lines to relay the information.
The analog information recorded by the microphones and cameras is broken down into discreet units, translating it to ones and zeros. A Codec encodes the information to a digital signal that can then be transmitted to a codec at the other end, which will retranslate these digital signals back into analog video images and audio sounds.
The theory's the same, the transmission has changed
In the earlier days of video conferencing, T1, ATM and ISDN lines were used almost exclusively but were really only practical for room-based video conferencing systems. These dedicated lines were expensive and only large corporations tended to have the facilities and money to invest in this type of set-up.
As the Internet became more a part of the everyday lives of all businesses, however, it changed how video conferencing was conducted. The TCP/IP connections of the Internet are much less expensive and can carry large quantities of information, including video packets for conferencing, relatively easily. Because of this, video conferencing has become much more prevalent in small Businesses and in desktop packages that can be set up with software for computer-to-computer networking.
Compression makes video transmission practical
The problem that arises when you convert analog to digital for transmission is the loss of clarity in an image. Analog signals are a continuous wave of amplitudes and frequencies showing shades and ranges of color as well as depth and brightness. When you convert to digital, which is strictly 0's and 1's, you then need to develop a grid to represent values, intensities and saturations of different color values so that the image can be interpreted and reformed at the receiving end.
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.
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