“A small step for man, but a giant leap for mankind", such were the words that travelled through space all the way from the Moon to our television sets as frames of Armstrong’s setting foot on the moon flashed across 600 million screens. It was indeed a technological milestone. But have ever wondered that people were sitting in their living rooms watching a mortal reach an alien land and show to you live pictures from there. Much before that feat, the technology to transmit video had been developed and was in itself a technological achievement. About half a century later, two-way communication involving real-time streaming of video and audio is becoming commonplace with almost every smart phone.
Video conferencing is a technology by means of which two or more parties situated in different geographical locations can watch and converse with each other by means of two-way transmission of video and audio data in near real-time.
From once being a high profile, owned by a famous few, this technology has made inroads to every middle class homestead that owns a healthy broadband connection. It can be a simple point to point conversation between two persons, or a multipoint conference between many at different locations. When video conferencing is offered on telephone networks, it is also called VVOIP (Video and Voice over Internet Protocol). Video Conferencing is almost a subset of Internet Multimedia Subsystems (IMS).
One of the first forms of videoconferencing evolved in the first half of the 20th century. It involved using two Close Circuit Television Systems transmitting analog data over a coaxial cable pair and found much use in the German Postal System during the pre World-War 2 era. Space Exploration Missions by NASA, and Television News channels actively used Ultra High Frequency (UHF) and Very High Frequency (VHF) band pairs in simplex modes to transfer data from one location to other and through satellites. But, the equipment was complex and costly and hence, not viable for consumer grade production. AT&T was the first to research the possibility of videoconferencing using an ordinary telephone network in the 1950s, but the research did not bear much fruit owing to the lack of technology. The bandwidth and digital transmission techniques for achieving high bitrates for the transmission of slow scan videos did not exist then. Lack of image compression tools resulted in poor video quality. Even the ‘Picturephone’ of 1970s failed to make an impact because of its cost. But the scene changed with the development of digital networks like ISDN in the 1980s. These networks assured a minimum bit rate of about 128 Kbps and led to the development of some of the world's first commercial videoconferencing systems.
Picture Tel Corp. sold its videoconferencing systems to many companies in 1984. In the very same year, William J. Tobin’s company developed a teleconferencing circuit board which was not only capable of up to 30 frames per second but was also small enough fit into a standard personal computer and was much cheaper than a dedicated solution. William also filed a patent for the codec for full motion videoconferencing, first demonstrated at AT&T Bell labs in 1986. 1990s saw rapid developments on this frontier and a gradual shift from proprietary equipment to standards-based technology promoted public availability. The development of IP-based media conferencing, more efficient video compression algorithms and evolution of digital networks made possible desktops and personal computer based videoconferencing. Project DIANE (Diversified Information and Assistance Network), a partnership between PictureTel and IBM Corporations in 1992 started to develop the first community service usage of this technology which over the next 15 years grew into a vast network of public service and distance education encompassing schools, libraries, museums etc. The year of 1995 saw the first of firsts in the digital video conferencing technology, like a client CU-SeeMe being used for the first live television broadcast on the day of Thanksgiving. World News Now hosted the first public video conference linking a techno fair at San Francisco with Capetown, and then the Winter Olympics were broadcasted in the same year.
The start of the new century saw the advent of video telephony through free internet services like Skype and similar online variants which though were of low quality, but also low cost videoconferencing solutions. The first HD video conferencing system came into market in 2005 by the company LifeSize Communication, capable of 30 HD fps. By the end of the decade, video telephony had started to make inroads into hand held mobile devices and smart phones.
Codecs are the underlying technologies that make videoconferencing tick. Codecs help in encoding audio and video stream into compact packets which can be transferred over a data network. In the absence of any codec, the analog audio and the media streams captured by the videoconferencing devices would form continuous wave forms which would require enormous amounts of bandwidth to be transmitted over the network. More on that later, but first, let us take a look at the block level components required for video conferencing starting from the transmitting end to the receiving end.