The process of converting the narration, dialogue, music and sound effects of a video production into text that is displayed on a television screen. The captions are typically white upper-case letters against a black background.

The preparation of captions for recorded programming so that, at the time of air or media playback, the captions are a part of the media. Appearance of captions is usually “pop-on” but could also be “roll-up.” Captions are typically placed in the upper or lower third of the television screen.

A phrase or sentence appears on the screen all at once – not line by line – stays there for a few seconds and then disappears or is replaced by another full caption. The captions are timed to synchronize with the program and placed on the screen to help identify the speaker. Pop-on captions are used for prerecorded captioning.

Pop-on captions are centered at the bottom third of the TV screen. Their placement is similar to subtitles although they are displayed as captions in white letters in a black box. Speaker changes are noted by a dash.

Roll-up captions roll onto and off the screen in a continuous motion. Usually two to three lines of text 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 all live captioning and can also be used for prerecorded captioning.

For prerecorded programming, roll-up captions can be timed to be closely synchronized with the audio.

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. Appearance of captions is “roll-up.”

Method of captioning in which captions are simultaneously prepared and transmitted at the time of origination by specially trained real-time captioners using a stenotype machine.

Live-display captioning is used when an accurate script and/or videotape is available prior to the time a program is telecast. Captions are prepared in advance and stored on a computer disk. As the program is telecast, a captioner pushes a button on the captioning system to display each caption. The roll-up captions appear line-by-line and are sync [..]

Captions that can only appear with the use of a decoder. The decoder may be either attached to a TV or built into TV’s 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 in [..]