Videotelephony
Encyclopedia
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.
At the dawn of the technology, videotelephony also included image phones which would exchange still images between units every few seconds over conventional POTS
-type telephone lines, essentially the same as slow scan TV
systems.
Currently videotelephony is particularly useful to the deaf and speech-impaired
who can use them with sign language
and also with a video relay service
, and well as to those with mobility issues
or those who are located in distant places and are in need of telemedical
or tele-educational
services.
It is also used in commercial and corporate settings to facilitate meetings and conferences, typically between parties that already have established relationships.
The concept of videotelephony was first popularized in the late 1880s in both the United States and Europe, although the sciences to permit its very earliest trials would take nearly a half century to be discovered. These evolved from studies and experimentation in the fields of electrical telegraphy, telephony
, radio
and television
.
The development of video and television transmission technologies in the United States and the United Kingdom started in the latter half of the 1920s, spurred notably by AT&T
, occurred in part to serve as an adjunct to the use of the telephone
. A number of organizations believed that videotelephony would be superior to plain voice telecommunication. However video technology
was to be deployed in analog
television broadcasting long before it could become practical in videotelephony.
Videotelephony can be categorized by its functionality, that is to its intended purpose, and also by its method of transmissions.
Videophone
s were the earliest form of videotelephony, dating back to initial tests in 1927 by AT&T. During the late 1930s the post offices of several European governments established public videophone services for person-to-person communications utilizing dual cable circuit telephone transmission technology. In the present day standalone videophones and UMTS video-enabled mobile phone
s are usually used on a person-to-person basis.
Videoconferencing
saw its earliest use with AT&T's Picturephone service in the early 1970s. Transmissions were analog over short distances, but converted to digital forms for longer calls, again using telephone transmission technology. Popular corporate videoconferencing systems in the present day have migrated almost exclusively to digital ISDN and IP
transmission modes due to the need to convey the very large amounts of data generated by their cameras and microphones. These systems are often intended for use in conference mode, that is by many people in several different locations, all of whom can be viewed by every participant at each location.
Telepresence
systems are a newer, more advanced subset of videoconferencing systems, meant to allow higher degrees of video and audio fidelity. Such high end systems are typically deployed in corporate settings.
Mobile collaboration
systems are another recent development, combining the use of video, audio, and on-screen drawing capabilities using newest generation hand-held electronic devices broadcasting over secure networks, enabling multi-party conferencing in real-time, independent of location.
Personal computer
based web cameras
are an often modest form of videotelephony, usually used for point-to-point videophone calls.
Each of the systems has its own advantages and disadvantages, including video quality
, capital cost
, degrees of sophistication, transmission
capacity requirements, and cost of use
.
At the dawn of the technology, videotelephony also included image phones which would exchange still images between units every few seconds over conventional POTS
Plain old telephone service
Plain old telephone service is the voice-grade telephone service that remains the basic form of residential and small business service connection to the telephone network in many parts of the world....
-type telephone lines, essentially the same as slow scan TV
Slow-scan television
Slow-scan television is a picture transmission method used mainly by amateur radio operators, to transmit and receive static pictures via radio in monochrome or color.A technical term for SSTV is narrowband television...
systems.
Currently videotelephony is particularly useful to the deaf and speech-impaired
Speech disorder
Speech disorders or speech impediments are a type of communication disorders where 'normal' speech is disrupted. This can mean stuttering, lisps, etc. Someone who is unable to speak due to a speech disorder is considered mute.-Classification:...
who can use them with sign language
Sign language
A sign language is a language which, instead of acoustically conveyed sound patterns, uses visually transmitted sign patterns to convey meaning—simultaneously combining hand shapes, orientation and movement of the hands, arms or body, and facial expressions to fluidly express a speaker's...
and also with a video relay service
Video Relay Service
A Video Relay Service , also sometimes known as a Video Interpreting Service, is a videotelecommunication service that allows deaf, hard-of-hearing and speech-impaired individuals to communicate over video telephones and similar technologies with hearing people in real-time, via a sign language...
, and well as to those with mobility issues
Disability
A disability may be physical, cognitive, mental, sensory, emotional, developmental or some combination of these.Many people would rather be referred to as a person with a disability instead of handicapped...
or those who are located in distant places and are in need of telemedical
Telerehabilitation
Telerehabilitation is the delivery of rehabilitation services over telecommunication networks and the internet. Most types of services fall into two categories: clinical assessment , and clinical therapy...
or tele-educational
Distance education
Distance education or distance learning is a field of education that focuses on teaching methods and technology with the aim of delivering teaching, often on an individual basis, to students who are not physically present in a traditional educational setting such as a classroom...
services.
It is also used in commercial and corporate settings to facilitate meetings and conferences, typically between parties that already have established relationships.
Early history
- Further information: Videophone -Early history
The concept of videotelephony was first popularized in the late 1880s in both the United States and Europe, although the sciences to permit its very earliest trials would take nearly a half century to be discovered. These evolved from studies and experimentation in the fields of electrical telegraphy, telephony
Telephony
In telecommunications, telephony encompasses the general use of equipment to provide communication over distances, specifically by connecting telephones to each other....
, radio
Radio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...
and television
Television
Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...
.
The development of video and television transmission technologies in the United States and the United Kingdom started in the latter half of the 1920s, spurred notably by AT&T
AT&T
AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...
, occurred in part to serve as an adjunct to the use of the telephone
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
. A number of organizations believed that videotelephony would be superior to plain voice telecommunication. However video technology
Video
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
was to be deployed in analog
Analog television
Analog television is the analog transmission that involves the broadcasting of encoded analog audio and analog video signal: one in which the message conveyed by the broadcast signal is a function of deliberate variations in the amplitude and/or frequency of the signal...
television broadcasting long before it could become practical in videotelephony.
Major categories
Videophone
Videophone
A videophone is a telephone with a video screen, and is capable of full duplex video and audio transmissions for communication between people in real-time...
s were the earliest form of videotelephony, dating back to initial tests in 1927 by AT&T. During the late 1930s the post offices of several European governments established public videophone services for person-to-person communications utilizing dual cable circuit telephone transmission technology. In the present day standalone videophones and UMTS video-enabled mobile phone
Mobile phone
A mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...
s are usually used on a person-to-person basis.
Videoconferencing
Videoconferencing
Videoconferencing is the conduct of a videoconference by a set of telecommunication technologies which allow two or more locations to interact via two-way video and audio transmissions simultaneously...
saw its earliest use with AT&T's Picturephone service in the early 1970s. Transmissions were analog over short distances, but converted to digital forms for longer calls, again using telephone transmission technology. Popular corporate videoconferencing systems in the present day have migrated almost exclusively to digital ISDN and IP
Internet Protocol
The Internet Protocol is the principal communications protocol used for relaying datagrams across an internetwork using the Internet Protocol Suite...
transmission modes due to the need to convey the very large amounts of data generated by their cameras and microphones. These systems are often intended for use in conference mode, that is by many people in several different locations, all of whom can be viewed by every participant at each location.
Telepresence
Telepresence
Telepresence refers to a set of technologies which allow a person to feel as if they were present, to give the appearance of being present, or to have an effect, via telerobotics, at a place other than their true location....
systems are a newer, more advanced subset of videoconferencing systems, meant to allow higher degrees of video and audio fidelity. Such high end systems are typically deployed in corporate settings.
Mobile collaboration
Mobile collaboration
Mobile collaboration is a technology-based process of communicating utilizing electronic assets and accompanying software designed for use in remote locations...
systems are another recent development, combining the use of video, audio, and on-screen drawing capabilities using newest generation hand-held electronic devices broadcasting over secure networks, enabling multi-party conferencing in real-time, independent of location.
Personal computer
Personal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...
based web cameras
Webcam
A webcam is a video camera that feeds its images in real time to a computer or computer network, often via USB, ethernet, or Wi-Fi.Their most popular use is the establishment of video links, permitting computers to act as videophones or videoconference stations. This common use as a video camera...
are an often modest form of videotelephony, usually used for point-to-point videophone calls.
Each of the systems has its own advantages and disadvantages, including video quality
Video
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
, capital cost
Capital cost
Capital costs are costs incurred on the purchase of land, buildings, construction and equipment to be used in the production of goods or the rendering of services, in other words, the total cost needed to bring a project to a commercially operable status. However, capital costs are not limited to...
, degrees of sophistication, transmission
Transmission (telecommunications)
Transmission, in telecommunications, is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless...
capacity requirements, and cost of use
Indirect costs
Indirect costs are costs that are not directly accountable to a cost object . Indirect costs may be either fixed or variable. Indirect costs include taxes, administration, personnel and security costs, and are also known as overhead.There are two types of Indirect Costs...
.
Categories by cost and quality of service
From the least to the most expensive systems:- Web cameraWebcamA webcam is a video camera that feeds its images in real time to a computer or computer network, often via USB, ethernet, or Wi-Fi.Their most popular use is the establishment of video links, permitting computers to act as videophones or videoconference stations. This common use as a video camera...
videophone and videoconferencing systems that serve as compliments to personal computers, connected to other participants by computerComputer networkA computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....
and VoIP networks –lowest direct cost assuming the users already possess computers at their respective locations. Quality of service can range from low to very high, including high definitionHigh-definition videoHigh-definition video or HD video refers to any video system of higher resolution than standard-definition video, and most commonly involves display resolutions of 1,280×720 pixels or 1,920×1,080 pixels...
video available on the latest model webcams; - VideophoneVideophoneA videophone is a telephone with a video screen, and is capable of full duplex video and audio transmissions for communication between people in real-time...
s –low to midrange cost. The earliest standalone models operated over either plain POTSPlain old telephone servicePlain old telephone service is the voice-grade telephone service that remains the basic form of residential and small business service connection to the telephone network in many parts of the world....
telephone lines on the PSTN telephone networks or more expensive ISDN lines, while newer models have largely migrated to Internet protocolInternet ProtocolThe Internet Protocol is the principal communications protocol used for relaying datagrams across an internetwork using the Internet Protocol Suite...
line service for higher image resolutions and sound quality. Quality of service for standalone videophones can vary from low to high; - Videoconferencing systemsVideoconferencingVideoconferencing is the conduct of a videoconference by a set of telecommunication technologies which allow two or more locations to interact via two-way video and audio transmissions simultaneously...
–midrange cost, usually utilizing multipoint control unitMultipoint Control UnitA Multipoint Control Unit is a device commonly used to bridge videoconferencing connections.The Multipoint Control Unit is an endpoint on the LAN that provides the capability for 3 or more terminals and gateways to participate in a multipoint conference...
s or other bridging services to allow multiple parties on a videoconference calls. Quality of service can vary from moderate to high; - Telepresence systemsTelepresenceTelepresence refers to a set of technologies which allow a person to feel as if they were present, to give the appearance of being present, or to have an effect, via telerobotics, at a place other than their true location....
–highest capabilities and highest cost. Full high-end systems can involve especially built teleconference rooms to allow expansive views with very high levels of audio and video fidelity, to permit an 'immersive' videoconference. When the proper type and capacity transmission lines are provided between facilities, the quality of service reaches state-of-the-art levels.
Sign language communications via videotelephony
- Main articles: Video Relay ServiceVideo Relay ServiceA Video Relay Service , also sometimes known as a Video Interpreting Service, is a videotelecommunication service that allows deaf, hard-of-hearing and speech-impaired individuals to communicate over video telephones and similar technologies with hearing people in real-time, via a sign language...
, a service for deaf, hard-of-hearing and speech-impaired (mute) users communicating with hearing persons at a different location, plus Video Remote InterpretingVideo Remote InterpretingVideo Remote Interpreting uses video or web cameras and telephone lines to provide sign language interpreting services, for deaf, hard-of-hearing or speech-impaired individuals, through an offsite interpreter, in order to communicate with hearing persons...
, where users are in the same location as their hearing parties.
See also
- Mobile collaborationMobile collaborationMobile collaboration is a technology-based process of communicating utilizing electronic assets and accompanying software designed for use in remote locations...
- List of video telecommunication services and product brands
- Project DIANEProject DIANEProject DIANE, an acronym for Diversified Information and Assistance NEtwork, was a very early videoconferencing based community service network created in the United States...
-a large U.S. business and social services videoconferencing network - TeleconferenceTeleconferenceA teleconference or teleseminar is the live exchange and mass articulation of information among several persons and machines remote from one another but linked by a telecommunications system...
- TelehealthTelehealthTelehealth is the delivery of health-related services and information via telecommunications technologies. Telehealth could be as simple as two health professionals discussing a case over the telephone or as sophisticated as doing robotic surgery between facilities at different ends of the...
- TelephonyTelephonyIn telecommunications, telephony encompasses the general use of equipment to provide communication over distances, specifically by connecting telephones to each other....
-the ancestral technology - Video Relay ServiceVideo Relay ServiceA Video Relay Service , also sometimes known as a Video Interpreting Service, is a videotelecommunication service that allows deaf, hard-of-hearing and speech-impaired individuals to communicate over video telephones and similar technologies with hearing people in real-time, via a sign language...
- VideophoneVideophoneA videophone is a telephone with a video screen, and is capable of full duplex video and audio transmissions for communication between people in real-time...
- WebcamWebcamA webcam is a video camera that feeds its images in real time to a computer or computer network, often via USB, ethernet, or Wi-Fi.Their most popular use is the establishment of video links, permitting computers to act as videophones or videoconference stations. This common use as a video camera...
Further reading
- Being There ProAV Magazine. 7 November 2008.
- Bajaj, Vikas. Transparent Government, Via Webcams in India, New York Times, July 18, 2011, pg.B3. Published online: July 17, 2011.