Broadly speaking, it can be said that videoconferencing is synchronous communication, with image, video and audio between two or more people, located in different geographical locations, who can connect through telephone networks or through multiservice IP Networks (COLCHER, 2005).
Videoconferencing was initially developed for use in business meetings between companies. However, due to the high costs and lack of infrastructure for bidirectional signal transmission, the technology could not be commercialized immediately. The use of videoconferencing became viable with improvements in the technologies used for video compression and transmission and the adoption of communication protocol standards between devices. With technological advances, there was an increase in the demand for the use of this means of communication. Consequently, the production of equipment increased and its costs were reduced slightly. However, if we compare the costs of the equipment with those of personal computers, which can also perform audiovisual communication functions, the former can be considered high.
In 1964, the videophone, the predecessor of videoconferencing, was introduced by American Telephone and Telegraph (AT&T), an American telecommunications company. The first interactive communication with video and audio occurred in 1967 between New York and Los Angeles, in the United States. In the 1980s, with the emergence of algorithmic compression, which with the use of CODECs (Encoder and Decoder) allows the compression of signals in digital format to divide the images into blocks with a size 'n' times smaller than the original, it was possible to use existing networks without compromising the quality of video and audio. In January 1986, Michael G. Moore of Penn State University, using circuits that transmitted data, began the first undergraduate courses transmitted by videoconferencing, with students in a studio on the University Park campus and groups in Erie, Pennsylvania (MOORE, 2008).
In the mid-1990s, with the use of CODEC, installed on a personal computer, it was possible to transmit videoconferencing with a transmission rate of 56 kbps.
Equipment manufactured up until the early 2000s used “personal computer” type hardware and proprietary software with the respective video, audio, network and other protocols. Currently, there are several models available, some of which are designed for specific applications, including use in education, and which may have an interactive Touch Screen command interface for the teacher. Although these devices may require some relatively complex configurations, they can be easily managed by simply touching the interactive screen, where a manual touch selects the peripheral that will transmit the image, video or audio to the other connected device(s). Peripherals may include video cameras, notebooks, digital whiteboards, tabletop and/or lapel microphones, DVD players and others.
After capturing the signals from these devices, the CODEC, through its processors, compresses the data and transmits it over the networks to other videoconferencing devices that use compatible protocols. These, in turn, decompress the data and display the image, video and audio in the other room(s).
Videoconferencing equipment can be fixed to racks or portable, and can be used, among other things, to implement courses in the blended mode, which, according to Moran (2002), includes both in-person and distance learning. Portable equipment can have video cameras incorporated into the CODEC cabinet, or separately. They are smaller in size when compared to fixed equipment. The main advantage of this type of equipment is mobility, which allows videoconferencing sessions to be held from any location with fixed or mobile networks.
There is a direct and close relationship between transmission/reception speed and image quality, since the higher the connection speed, the better the image quality, although this is not the only factor that defines it. Quality also depends on the configuration of the video, audio and other protocols of the equipment. It is known that the protocols recently implemented in the equipment provide better quality for the image, video and audio than those that were initially developed with the invention of videoconferencing technology. However, it is necessary that the other connected equipment also use these protocols. If this does not occur, the equipment must be reconfigured for connections with available and compatible protocols, which can often have a lower data processing capacity than those recently developed, which
can compromise the quality of the video conference session and consequently the class. There are also other factors that must be considered in order to have a successful video conference session.
success, which are: the processing power of the equipment, the traffic capacity of the routers and switches to which the videoconferencing equipment is connected when
make connections through multiservice IP networks; the signal strength of mobile networks; the sensitivity of the microphone(s); the image resolution of the camera(s), and others.
