Video conferencing systems are systems in which one group of participants communicates visually and verbally in real time with a second, remote group of participants. In addition to video conferencing, presentations on whiteboards and documents or moving image presentations can also be transmitted. However, this transmission is more complex than web conferencing.
In real-time video transmission, the video signals, like the voice signals, are digitized, compressed and then transmitted between two or more conference rooms simultaneously. There are specially equipped rooms for video conferencing. Usually, such a room has a conference table for the participants, video cameras for recording and displays on which the other conference group is shown. In these systems, transmission takes place via high-speed connections and, in the case of intercontinental connections, via satellites.
In addition to videoconferencing with point-to-point connection between two participants, there is also telepresence via personal computers and multipoint videoconferencing between several participants. This concept works with a Multipoint Control Unit( MCU), which converts the video signals in a relatively complex way.
Video conferencing can increase employee productivity and improve communication and interaction among colleagues, customers, suppliers, and business partners. Project times can be shortened, time on the job increased, and business travel costs reduced.
In conjunction with the transmission of streaming media, compressed image files and sound files over IP-based networks, the International Telecommunication Union( ITU) has adopted recommendations for videoconferencing since 1990 that include the various networks, connection types, interfaces and media. All videoconferencing uses H.264/ AVC video compression. For transmission, the ITU has defined three overarching standards: H.320 videoconferencing over public digital telephone networks, H.323 for multimedia applications, and H.324 for transmission over public analog telephone networks( POTS).
Videoconferencing standards: H.320: H.320 is about the transmission of videoconferences over ISDN.
H.321:H.321 specifies the use for ISDN B channels.
H.324: H.324 defines the standards for the transmission of audio, video and data streams over the normal low-bandwidthtelephone network (POTS)
T.120:Protocols for data exchange in multimedia conferences
G.723.1/G.729:G.723 deals with an algorithm for the transmission of voice. The compression factor for the data is 10.
In addition to the ITU recommendations, there is also Video-as-a-Service( VaaS), a cloud service for video conferencing through which companies support collaboration with employees and customers. Furthermore, with Computer Supported Cooperative Work( CSCW), a PC-based method for cooperative work exists, although it has certain limitations. The further development of video conferencing leads to telepresence with virtually present participants.