Closed captioning

Closed captioning (CC) is the process of displaying text on a television, video screen, or other visual display to provide additional or interpretive information, where the viewer is given the choice of whether the text is displayed. Closed captions are typically used as a transcription of the audio portion of a program as it occurs (either verbatim or in edited form), sometimes including descriptions of non-speech elements. Other uses have included providing a textual alternative language translation of a presentation's primary audio language that is usually burned-in (or "open") to the video and unselectable.

HTML5 defines subtitles as a "transcription or translation of the dialogue when sound is available but not understood" by the viewer (for example, dialogue in a foreign language) and captions as a "transcription or translation of the dialogue, sound effects, relevant musical cues, and other relevant audio information when sound is unavailable or not clearly audible" (for example, when audio is muted or the viewer is deaf or hard of hearing).

The term closed indicates that the captions are not visible until activated by the viewer, usually via the remote control or menu option. On the other hand, the terms open, burned-in, baked on, hard-coded, or simply hard indicate that the captions are visible to all viewers as they are embedded in the video.

In the United States and Canada, the terms subtitles and captions have different meanings. Subtitles assume the viewer can hear but cannot understand the language or accent, or the speech is not entirely clear, so they transcribe only dialogue and some on-screen text. Captions aim to describe to the deaf and hard of hearing all significant audio content—spoken dialogue and non-speech information such as the identity of speakers and, occasionally, their manner of speaking—along with any significant music or sound effects using words or symbols. Also, the term closed caption has come to be used to also refer to the North American EIA-608 encoding that is used with NTSC-compatible video.

The United Kingdom, Ireland, and a number of other countries do not distinguish between subtitles and captions and use subtitles as the general term.^{[citation needed]} The equivalent of captioning is usually referred to as subtitles for the hard of hearing. Their presence is referenced on screen by notation which says "Subtitles", or previously "Subtitles 888" or just "888" (the latter two are in reference to the conventional videotext channel for captions), which is why the term subtitle is also used to refer to the Ceefax-based videotext encoding that is used with PAL-compatible video. The term subtitle has been replaced with caption in a number of markets—such as Australia and New Zealand—that purchase large amounts of imported US material, with much of that video having had the US CC logo already superimposed over the start of it. In New Zealand, broadcasters superimpose an ear logo with a line through it that represents subtitles for the hard of hearing, even though they are currently referred to as captions. In the UK, modern digital television services have subtitles for the majority of programs, so it is no longer necessary to highlight which have subtitling/captioning and which do not.^{[citation needed]}

Remote control handsets for TVs, DVD players, and similar devices in most European markets often use "SUB" or "SUBTITLE" on the button used to control the display of subtitles and captions.

Regular open-captioned broadcasts began on PBS's The French Chef in 1972. WGBH began open captioning of the programs Zoom, ABC World News Tonight, and Once Upon a Classic shortly thereafter.

Closed captioning was first demonstrated in the United States at the First National Conference on Television for the Hearing Impaired at the University of Tennessee in Knoxville, Tennessee, in December 1971. A second demonstration of closed captioning was held at Gallaudet College (now Gallaudet University) on February 15, 1972, where ABC and the National Bureau of Standards demonstrated closed captions embedded within a normal broadcast of The Mod Squad. At the same time in the UK the BBC was demonstrating its Ceefax text based broadcast service which they were already using as a foundation to the development of a closed caption production system. They were working with professor Alan Newell from the University of Southampton who had been developing prototypes in the late 1960s which became part of the core specification of the Teletext platform.