page_title: Videotelephony
section_title: Components and types
hierarchical_section_title: Videotelephony / Technology / Components and types
caption_attribution_description: English: Full HD VideoConferencing System by LifeSize
context_page_description: Videotelephony comprises the technologies for the reception and transmission of audio-video signals by users at different locations, for communication between people in real time. A videophone is a telephone with a video display, capable of simultaneous video and audio for communication between people in real time. Videoconferencing implies the use of this technology for a group or organizational meeting rather than for individuals, in a videoconference. Telepresence may refer either to a high-quality videotelephony system or to meetup technology, which goes beyond video into robotics. Videoconferencing has also been called "visual collaboration" and is a type of groupware.
  While development of video conferencing started in the late 19th century, the technology only became available to the public starting in the 1930s. These early demonstrations were installed at "booths" in post offices and shown at various world expositions. It took until 1970 for AT&T to launch the first true video conferencing system, wherein anyone could subscribe to the service and have the technology in their home or office.
context_section_description: The core technology used in a videotelephony system is digital compression of audio and video streams in real time. The hardware or software that performs compression is called a codec (coder/decoder). Compression rates of up to 1:500 can be achieved. The resulting digital stream of 1s and 0s is subdivided into labeled packets, which are then transmitted through a digital network of some kind (usually ISDN or IP).
  The other components required for a videoconferencing system include:
  Video input: (PTZ / 360° / Fisheye) video camera, or webcam
  Video output: computer monitor, television, or projector
  Audio input: microphones, CD/DVD player, cassette player, or any other source of PreAmp audio outlet.
  Audio output: usually loudspeakers associated with the display device or telephone
  Data transfer: analog or digital telephone network, LAN, or Internet
  Computer: a data processing unit that ties together the other components, does the compressing and decompressing, and initiates and maintains the data linkage via the network.
  There are basically two kinds of videoconferencing and videophone systems:
  Dedicated systems have all required components packaged into a single piece of equipment, usually a console with a high quality remote controlled video camera. These cameras can be controlled at a distance to pan left and right, tilt up and down, and zoom. They became known as PTZ cameras. The console contains all electrical interfaces, the control computer, and the software or hardware-based codec. Omnidirectional microphones are connected to the console, as well as a TV monitor with loudspeakers and/or a video projector. There are several types of dedicated videoconferencing devices:
  Large group videoconferencing are built-in, large, expensive devices used for large rooms such as conference rooms and auditoriums.
  Small group videoconferencing are either non-portable or portable, smaller, less expensive devices used for small meeting rooms.
  Individual videoconferencing are usually portable devices, meant for single users, and have fixed cameras, microphones, and loudspeakers integrated into the console.
  Desktop systems are add-ons (hardware boards or software codec) to normal PCs and laptops, transforming them into videoconferencing devices. A range of different cameras and microphones can be used with the codec, which contains the necessary codec and transmission interfaces. Most of the desktops systems work with the H.323 standard.
  WebRTC Platforms are video conferencing solutions that are not resident by using a software application but is available through the standard web browser. Solutions such as Adobe Connect and Cisco WebEX can be accessed by going to a URL sent by the meeting organizer and various degrees of security can be attached to the virtual "room". Often the user will be required to download a piece of software, called an "Add In" to enable the browser to access the local camera, microphone and establish a connection to the meeting. WebRTC technology doesn't require any software or Add On installation, instead a WebRTC compliant internet browser itself acts as a client to facilitate 1-to-1 and 1-to-many videoconferencing calls. Several enhanced flavours of WebRTC technology are being provided by Third Party vendors.
caption: Components of a LifeSize Communications Room 220 high-definition multipoint system
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