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
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
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
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
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
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