Closed captioning refers to the display of text on a television or video screen and is created to make an audio representation of the audio and video signals. Formerly developed for the hearing-impaired, it is also used as a teaching device for those learning English. The use of the word, 'closed' is to imply the viewer's ability to make a choice of whether or not to have text display on the screen. Closed captions appear on the television screen only if the viewer chooses to decode or activate them. On the other hand, open captioning is visible to all the viewers by default.
According to some, there is no difference between subtitles and closed captioning. However, the contrary is true. Subtitles are designed for those who do not understand the language in which that movie or video is. A movie in French language can have English subtitles so that the English audiences face no problems understanding the story of the movie. Subtitles are a close translation of the dialogs between the movie characters. The dialogs translated in another language help the viewers to follow the film or television show. Closed captioning refers to the facility to turn on captions that describe the audio content of the movie. It is not merely a translation of the dialogs. It is rather a description of the entire audio and non-speech content of the film.
It has served as a boon for those hard of hearing. Those with a loss of hearing can enjoy audio-visual media by reading the captions superimposed on the screen. The captions relate the verbal information in written form. They also convey to the viewers, the information that is implied by non-verbal means. Closed captioning includes the introduction of characters as also the symbolic representation of music and sound effects used in the movie.
Spectators can choose to mute their televisions and use only the captions. In case of taking a phone or any such interruptions, one can choose to mute the television set and turn the closed captioning facility on. Closed captioning can also help those learning a non-native language and finding it difficult to understand the language pronunciation.
Captions are displayed in a roll-up or pop-up fashion. Pop-up captions are commonly seen in pre-recorded programs while roll-up captions appear in programs aired live. Special expertise is required to provide live transmissions with closed captions. Paint-on captions appear letter by letter across the screen and are used quite rarely. Closed captioning is implemented by means of a decoder circuitry, which can be turned on to make visible the captions embedded in the vertical blanking interval. The blanking interval is the 21-line portion that does not contain picture information. The captions are encoded as a part of the electronic signal and thus the captioned program can be transmitted over air or satellite. If you see the symbol 'CC' after the movie title or program name, you can be sure that the program has the closed captioning facility.
Today, closed captioning widely supplements the audio-visual media. Catering to diverse audiences, it has earned popularity.