Specifications

Basic Captioning Terms
Off-line captioning:
Captioning that is produced after a video segment has been recorded. A captioner watches
the video recording and creates captions, paying attention to the timing and screen placement
of each caption. The captions are usually then recorded on a videotape with the program
picture and sound before the program is broadcast or distributed. Most captioned
programming is produced off-line.
Real-time captioning:
Captions that are simultaneously created and transmitted during a video program or
conference. This type of captioning is most frequently used for live programs, including
news shows and sporting events. A trained stenotypist, acting in much the same way as a
courtroom reporter, enters the spoken content by typing phonetic codes on a special keyboard
that permits high-speed transcription. A computer, using custom software, then very quickly
translates the phonetic codes into proper words. In order to display the words as quickly as
possible after they are spoken, most realtime captioning is shown in a scrolling style.
Closed captions:
Captions that appear only when special equipment called a decoder is used. Closed
captioning is typically used for broadcast television and for videocassettes of movies that are
widely distributed. Closed captioning allows caption users (people who are deaf or hard of
hearing) to enjoy the same broadcast and pre-recorded video materials that other television
viewers enjoy.
Open captions:
Captions visible without using a decoder. When a video is open captioned, the captions are
permanently part of the picture. Open captions are advised for any situation where a decoder
may be difficult to obtain or operate (for example, in a hotel, convention center, or museum).
For this reason, open captioning is recommended for training and promotional videos.
Closed caption decoder:
Equipment that decodes the captioning signal and causes captions to appear on the screen. In
the 1980s and early 1990s, closed caption decoders were usually separate appliances that
connected to the television set, VCR, and/or cable converter box. Since July 1, 1993, all
television receivers with screens 13 inches or larger manufactured for sale in the United
States must have built-in closed caption decoders, and the additional appliance will not be
needed for these sets.
Roll-up and Pop-On captions:
These are the two main styles in which captions may appear. Roll-up captions scroll onto and
off the screen in a continuous motion. Pop-on captions do not scroll; the words display and
erase entirely together. Pop-on captions are used for most off-line captioning. Roll-up
captions are used for most real-time captioning.
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