Types, Methods, and Styles
Types
Types of captioning vary according to how the captions appear, how they are accessed, and what information is provided.
Two types of captions exist today: “closed” and “open.” To understand the difference, one first needs to understand how the terms “closed” and ”open” originated.
Open captions, sometimes called subtitles, were developed specifically for both deaf and hard of hearing viewers. Captioned Films for the Deaf, a private corporation in the late 1940s, was the forerunner of the DCMP and produced the first open captions for entertainment and educational productions in 16mm format. Three decades later, closed captions were developed for television, and still later subtitles for the deaf and hard of hearing (SDH) were introduced on DVD. Not to be confused with subtitles for foreign films, captions and SDH display spoken language and narration along with providing speaker identification, sound effects, and other features.
The terms “closed” and “open” arose in part from the technology used to deliver TV captions. TV closed captions are hidden in line 21 of the analog video signal (also known as the vertical blanking interval or VBI). A set-top decoder or built-in chip must be used to decode, or open, the captions. Television captions are called “closed” because they must be decoded to become part of the television picture. Once decoded, captions are referred to as “open.” Most TV captions are referred to as “closed captions.”
The meaning of closed and open captions is similar, though slightly different, in the computer industry. In a PC environment, a closed caption is caption text that can be turned on or off and even styled by the user. An open caption is a caption that cannot be turned off—it is part of the static or dynamic image file; it is painted in the picture pixels. DVD captions for viewers who are deaf or hard of hearing may be turned on or off, and they are either called “closed captions” (decoder required) or “subtitles for the deaf and hard of hearing” (menu driven). internet captions are generally referred to as “closed captions,” and they are media player–based (e.g., QuickTime, Windows Media, Flash, RealMedia).
Terminology to describe closed and open captions varies widely and is often confusing to consumers. DCMP provides most of its media in open-captioned form, though it also provides closed captioning.
Example: Subtitles for the Deaf and Hard of Hearing (SDH)
Example: Line 21 Television Captions in Uppercase
Example: Line 21 Television Captions in Mixed-Case
Methods
Methods vary according to when the captions are created and displayed.
Off-Line (Prerecorded)
Off-line captions are created and added after a production has been recorded, but before it is aired or played. Examples of productions that utilize off-line captioning are broadcast TV programs, home videos, and educational media. Most of these captions appear in the pop-on style.
On-Line (Real-Time or Live)
On-line captions are created and added during a live broadcast or event. This method is used to describe the captioning of live political debates, sporting events, classroom lectures, business seminars, and other live productions. Most of these captions appear in the roll-up style.
Styles
Styles refer to the way captions are presented. The method of the captioning sometimes dictates the style.
Pop-On
Usually one to three lines of pop-on captions appear on-screen all at once, stay there for a few seconds, and then are replaced by another caption. The captions are timed to synchronize with the audio and are placed on the screen in such a way as to help identify the speaker. They should not cover up graphics and other essential visual elements of the picture.
The DCMP requires pop-on captions in upper- and lowercase letters. Characters must be a font similar to Helvetica medium. These captions must have good resolution and fit the requested 32 characters to a line.
Roll-Up
Each line of captions rolls onto and off the screen in a continuous motion. Usually two to four lines of text appear at one time, with the top line of the text disappearing as a new bottom line is added. Roll-up captions are mostly used for on-line captioning, but they are sometimes used for some off-line captioning as well. These are synchronized less precisely than pop-on captions. Although it is possible to move captions (to avoid graphics), more often they remain in one place throughout the program. Double chevrons are often used to indicate a change in speaker, but the speaker is not always identified.
