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Glossary of Captioning Terms

Universal Access - Alternative Media - Captioning

NCI's Glossary of Captioning Terms

Captioning: The process of converting the audio portion of a video production into text which is displayed on a television screen. The captions are typically white upper-case letters against a black background.

Off-line Captioning: The preparation of captions for recorded programming so that, at time of air or tape playback, the captions are a part of the videotape. Appearance of captions is usually "pop-on." Captions are typically placed in the upper and lower third of the television screen.

Pop-on Captions: A phrase or sentence appears on the screen all at once--not line-by-line-stays there for a few seconds, usually in sync with the audio, and then it disappears or is replaced by another full caption. Pop-on captions are used for most off-line captioning.

On-line Captioning:Captioning that is provided at the time of program origination. "Real-time," "live-display" and a combination of the two are all methods of on-line captioning. This type of captioning is most frequently used for live programs. Appearance of captions is "roll-up."

Roll-up Captions:Roll-up captions roll onto and off the screen in a continuous motion. A maximum of four lines of text can appear at one time. As a new line comes along, it appears on the bottom, pushing the other lines on the screen up. Roll-up captions are used for most on-line captioning.

Real-time Captioning: Method of captioning where captions are simultaneously prepared and transmitted at time of origination by specially trained real-time captioners using a stenotype machine.

Real-time Dictionary: A computerized dictionary that is comprised of the phonetics and their corresponding English that the captioner uses to build words and create punctuation. Real-time captioners write phonetically what they hear. Similar to a piano, multiple keys are depressed on a steno machine to create different word combinations. No two captioners write exactly the same way, so each has a custom dictionary.

Live-display Captions: Live-display captioning is used when an accurate script and/or videotape is available in advance. The text of the program is transcribed and stored on a computer disk. At time of air, the captioner manually displays the already-prepared captions. Usually live-display captions are roll-up, so the captioner displays them line-by-line, as much in sync with the program audio as possible.

Closed Captions:Captions that can only appear with the use of a decoder. The decoder may be either attached to a TV or built into the newer TVs made after July 1993. Closed captioning allows caption users to enjoy the same broadcast and recorded video materials that other television viewers enjoy. Closed-caption information is carried in Line 21 of the vertical blanking interval of the television signal.

Open Captions:Captions that are visible without using a set-top decoder or a TV with a built-in decoder chip. When a video is open captioned, the captions are permanently part of the picture.

Closed Caption Decoder: A small electronic device that decodes the captioning signal and causes captions to appear on the screen. In the 1980s and early 1990s, closed caption decoders were the major means by which consumers could watch captioned television. After July 1, 1993, all television sets with screens 13" or larger manufactured for sale in the United States must have a built-in decoder chip.

Caption Disk: A computer diskette that stores a program's caption information, including the text, timing and placement information. The caption disk is used in conjunction with an encoder to create the captioned submaster.

Encoding: The process of inserting the caption data into the television signal on Line 21.

Encoder: A device that electronically inserts the caption data into the TV signal on Line 21.

Line 21:The television signal is comprised of 525 lines. The vertical blanking interval encompasses Line 1 through 21. The caption information resides on Line 21, and active video starts on Line 22.

Time-code: An electronic signal embedded in a videotape that discretely identifies each frame of video.

Master: The original, first-generation videotape of the final version of a program. The master is the source videotape used to create a captioned "submaster."

Submaster: Any duplication created from the master videotape. The captioned videotape is a submaster of the original.

Automatic Live Encoding (ALE): When production schedules are tight, this is an alternate means of transmitting or displaying captions. Automatic live encoding makes use of the same caption creation techniques used in prerecorded captions, but a different method is used to trigger the data into Line 21 of the television signal. The captioned data is loaded into the computer, and the internal clock within the computer is used to trigger the captions as opposed to using time-code from the program videotape. A manual trigger is used to start the transmission of data between the computer and the smart encoder. The display of automatic live encoding is pop-on, the same as used for prerecorded captions.

Subtitles:Permanently affixed on-screen text that represents the narration, dialogue, music, or sound effects in a program. Subtitles are created with a character generator; no decoding capability is required for viewing them. Subtitles are usually in upper- and lower-case letters and do not appear in a black background. Also, subtitles are typically placed at the bottom center of the television screen.

Reformat: The process of revising previously captioned programs for rebroadcast, requiring the retiming and/or editing of caption text to synchronize it to the edited video and audio