Videotelephony, also known as video chat, videoconferencing, video calling, or telepresence, is the use of audio and video for simultaneous two-way communication. Videophones were standalone devices for video calling (compare Telephone). As smartphones and computers have become capable of video calling, the demand for a separate category of videophones has disappeared. Videoconferencing implies group communication and is used in telepresence, the goal of which is to create the illusion that remote participants are in the same room. The concept of videotelephony was conceived in the late 19th century, and versions were demonstrated to the public starting in the 1930s. In April, 1930, reporters gathered at AT&T corporate headquarters on Broadway in New York City for the first public demonstration of two-way video telephony. The event linked the headquarters building with a Bell laboratories building on West Street. Early demonstrations were installed at booths in post offices and shown at world expositions. AT&T demonstrated Picturephone at the 1964 World’s Fair in New York City. In 1970, AT&T launched Picturephone as the first commercial personal videotelephone system. In addition to videophones, there existed image phones which exchanged still images between units every few seconds over conventional telephone lines. The development of advanced video codecs, more powerful CPUs, and high-bandwidth Internet service in the early 2000s allowed the new category of smartphones to provide high-quality low-cost color service between users almost anywhere in the world, eliminating the videophone as a separate product concept. Applications of videotelephony include sign language transmission for deaf and speech-impaired people, distance education, telemedicine, and overcoming mobility issues. News media organizations have used videotelephony for broadcasting.
History
Origin The concept of videotelephony was first conceived in the late 1870s, both in the United States and in Europe, although the basic sciences to permit its very earliest trials would take nearly a half century to be discovered. The prerequisite knowledge arose from intensive research and experimentation in several telecommunication fields, notably electrical telegraphy, telephony, radio, and television.
Early systems Simple analog videophone communication could be established as early as the invention of the television. Such an antecedent usually consisted of two closed-circuit television systems connected via coax cable or radio. An example of that was the German Reich Postzentralamt (post office) videotelephone network serving Berlin and several German cities via coaxial cables between 1936 and 1940.
Gregorio Y. Zara, a Filipino scientist, invented the first videophone in 1954, which was patented in 1955 as a "photo phone signal separator network." He is recognized as the Father of Videoconferencing for his pioneering contribution to the development of videotelephony technology. The development of videotelephony as a subscription service started in the latter half of the 1920s in the United Kingdom and the United States, spurred notably by John Logie Baird and AT&T's Bell Labs. This occurred in part, at least with AT&T, to serve as an adjunct supplementing the use of the telephone. A number of organizations believed that videotelephony would be superior to plain voice communications. Attempts at using normal telephony networks to transmit slow-scan video, such as the first systems developed by AT&T Corporation, first researched in the 1950s, failed mostly due to the poor picture quality and the lack of efficient video compression techniques. During the first crewed space flights, NASA used two radio-frequency (UHF or VHF) video links, one in each direction. TV channels routinely use this type of videotelephony when reporting from distant locations. The news media were to become regular users of mobile links to satellites using specially equipped trucks, and much later via special satellite videophones in a briefcase. This technique was very expensive, though, and was not adopted for applications such as telemedicine, distance education, and business meetings. Decades of research and development culminated in the 1970 commercial launch of AT&T's Picturephone service, available in select cities. However, the system was a commercial failure, chiefly due to consumer apathy, high subscription costs, and lack of network effect—with only a few hundred Picturephones in the world, users had extremely few contacts they could actually call, and interoperability with other videophone systems would not exist for decades.
Digital In the 1980s, digital telephony transmission networks became possible, such as with ISDN networks. During this time, there was also research into other forms of digital video and audio communication. Many of these technologies, such as the Media space, are not as widely used today as videoconferencing but were still an important area of research. The first dedicated systems started to appear as ISDN networks were expanding throughout the world. One of the first commercial videoconferencing systems sold to companies came from PictureTel Corp., which had an initial public offering in November, 1984. In 1984, Concept Communication in the United States created a circuit board for standard personal computers that doubled the video frame rate of typical digital videotelephone systems from 15 to 30 frames per second, and reduced the cost from $100,000 to $12,000. The company also secured a patent for a codec for full-motion videoconferencing, first demonstrated at AT&T Bell Labs in 1986.
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