subject: A Brief History Of Closed Caption Tv How And Why Did It Come About? [print this page] What are closed captions? What are closed captions?
Closed captions are captions that are embedded into the video signal; they are used to aid those with hearing impairments and they are invisible unless you use a special decoder. These closed captions are hidden in line 21 of the vertical blanking interval (VBI), and this is what enables you to turn subtitles on and off.
How did closed captions come about?
In 1970 the National Bureau of Standards (NBS) began looking into the possibility of using a portion of the network television signal to send precise time information on a nationwide basis. The ABC-TV network agreed to be involved in the research and implementation of this idea. When this project didnt work out ABC suggested that it might be possible to transmit captions instead.
Captioning was first revealed to the public in 1971, at the first National Conference on Television for the Hearing Impaired in Nashville, Tennessee. The second preview of closed captioning was shown on February the 15th 1972 at Gallaudet College. Both NBS and ABC presented closed captions embedded in the show The Mod Squad. The Federal Government funded the final development and testing of the system, and in 1973 the engineering department of the Public Broadcasting System began working on closed caption TV under contract to the Bureau of Education for the Handicapped of the Department of Health, Education and Welfare (HEW).
In 1976 the Federal Communications Commission set aside line 21 for the transmissions of closed captions in the United States. Public Broadcasting Service (PBS) engineers developed caption-editing consoles, which could be used to caption prerecorded programs. This was the equipment that other broadcasters would use to add captions to their programmes.
The first closed captioned television series was broadcast on March 16th 1980. The captions were seen in all households with the first generation of closed caption encoders. The ABC Sunday Night Movie (ABC), The Wonderful World of Disney (NBC) and Masterpiece Theatre (PBS) were all broadcast on March 16, 1980. Real time captioning was later developed in 1982 by the NCI; this technique would be used for captioning sports events, news broadcasts or any other live events that were broadcast on TV.
In the present day it is pretty rare that you will find a TV set that doesnt have a built in caption decoder, or at least this is the case in Western cultures, as the Television Decoder Circuitry Act of 1990 states that all TVs manufactured for sale in the USA must have a built in caption decoder.
