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Overview of Closed Captioning
Oregon's Deaf and Hard of Hearing Services (ODHHS)-Technical Assistance Center
ODHHS Information and Technical Assistance Series

Overview of Closed Captioning
(Source: Gary Robson)
What are closed captions?
Just as a caption in a book is the text under a picture, captions on video are text located somewhere on the picture. Since there is no way for a television to put text outside the area of the picture tube, captions do end up covering a portion of the picture (there are non-broadcast applications where this can be done).
CLOSED captions are captions that are hidden in the video signal, invisible without a special decoder. The place they are hidden is called line 21 of the vertical blanking interval (VBI). For more detail, see the "technical stuff" portion of this FAQ.
OPEN captions are captions that have been decoded, so they have become an integral part of the television picture, like subtitles in a movie. In other words, open captions cannot be turned off. The term "open captions" is also used to refer to subtitles created with a character generator.
How can I see closed captions on my television?
There are two ways to accomplish this: by using an external decoder, or by using a television with a decoder built in. External decoders are available from several sources, and a law in the United States called the Television Decoder Circuitry Act of 1990 mandates that since July 1993, all televisions manufactured for sale in the U.S. must contain a built-in caption decoder if the picture tube is 13" or larger. See "What is the Television Decoder Circuitry Act?" for more information about the TDCA, or read the full text of the Act on Cheetah´s Web site.
All decoders in North America are Line 21 decoders, named for the place where the captions are encoded.
See "Who manufactures caption decoders?" for a list of the companies that manufacture external decoders.
Will DTV (a.k.a. HDTV or ATV) have captions?
Our new digital TV standard, known as DTV (digital TV), HDTV (high-definition TV), or ATV (advanced TV), will definitely be able to carry captioning information, using the new EIA-708 captioning standard for digital programming.
Can I get captions with cable TV?
Absolutely. Since the caption data is "hidden" in the picture, it will reach you no matter how the TV signal gets to your set. There are problems from time-to-time with delivery of captions on the lower-budget cable systems, however. Much of this comes from the use of equipment that either "cleans up" or "compresses" the television signal, losing the VBI (where the captions are carried) when it is done.
Cable TV companies are, however, required by the FCC to maintain captioning information. If you see a show through cable that you know to have captions, and the captions aren´t coming through for you, contact the cable TV company and remind them of this!
Can I get captions from a satellite dish?
Yes. Just like with cable TV, the caption data is "hidden" in the picture, it will reach you no matter how the TV signal gets to your set. This is true both of the "big dishes" used for traditional analog satellite broadcasts, and the new DSS (Digital Satellite Service) dishes used by companies like USSB and DirecTV.
Are there captions on laser discs?
Laser discs certainly can have captions, which is not to say that all laser discs do have captions. Although not always reliable, your best bet is to look over the sleeve for a "CC." If you don´t find it, ask about it. If you´re in a rental place, ask them to play a short snippet for you so that you can see if it is captioned.
Are there captions on DVDs?
In the DVD arena, the standards committees didn´t move fast enough, and everyone came up with their own ideas of how to caption a DVD. There is DVD captioning being done in quite a few different languages, but we still don´t have industry-wide adherence to a single standard.
Are there captions on CD-ROM and Web multimedia?
For digital video on the Internet and CD-ROMs, Microsoft has proposed a new standard called SAMI (Synchronized Accessible Media Interchange), which will allow captioning of any digital multimedia file. Also, the National Center for Accessible Media (NCAM) is captioning video clips for the Web today. NCAM is using extensions to the QuickTime video format.
Can a movie in a theater be captioned?
Subtitling, which is visible to everyone in the theater, has been the only way to "caption" a movie. Now, the National Center for Accessible Media (NCAM) has developed a system known as the Rear Window captioning system, which uses clear acrylic panels that reflect captions which are displayed in reverse in the back of the theater. This allows people who want or need captions to have them without everybody being forced to see them.
What´s the difference between "caption" and "text" on the decoder?
Most external decoders and TV sets with built-in Line 21 decoders have an option for "text" and an option for "captions." The text option, instead of displaying a few lines of captions somewhere on the picture, takes over all or half of the screen to display scrolling text information.
Very few broadcasters are using the text fields now, so most of the time there will be no information there to see. Exceptions are TSN, CBC/Radio-Canada, and Global in Canada, and some ABC broadcasts in the USA.
Who do I talk to if I want my favorite show to be captioned?
If your favorite show doesn´t have captions, and you´d like it to, your first step is to find out who produces it. If it is a national show, it will be more effective to contact the network and/or the production company than to contact your local television station, although it never hurts to do both. In either case, ask for the public relations department first. If they can´t take care of you, they can always direct you to someone who can.
If you are attempting to start a large-scale lobbying effort to get captions on a show, make sure you have facts and figures before you contact the station. Be prepared to tell them how many deaf and hard-of-hearing viewers there are in the area, which of their advertisers have captioning, and what their competitors are doing in that time slot. See if there are any applicable laws mandating captioning. You can even track down captioning firms and provide the station with their names and phone numbers (make sure to provide more than one, or it will look like the captioning firm is orchestrating your efforts). Petitions are highly effective as well.
The absolute best way to get a program captioned, however, is to find a sponsor and present it to the station as a fait accompli.
Also, see my article, What to do when a show isn´t captioned.
How many people have televisions with caption decoders?
As of July, 1993, when theTelevision Decoder Circuitry Act took effect, roughly 500,000 standalone decoders had been sold (almost all from NCI), and roughly 1,000,000 televisions with caption decoders (mostly from Zenith). Since that date, roughly 20,000,000 televisions per year are being sold with caption decoders in them. At the time of this writing (February, 1997), that would make an estimated 70,000,000 TV´s with decoders in North America.
According to the Caption Center, it is expected that every home in the United States will have a caption-capable television set by the year 2000.
Where do captions come from?
Captions can be placed on a video signal in one of two ways: Online (live) or Offline (post-production).
Online captioning is done as an event occurs. Examples of online captioning are television news shows, live seminars, and sports events. Online captions can be done from a script, or actually created in realtime (see the next question).
Offline captioning is done "after the fact," in a studio. Examples of offline captioning include television game shows, videotapes of movies, and corporate videotapes (e.g. training videos). The text of the captions is created on a computer, and synchronized to the video using timecodes. They are then transferred to the videotape before it is broadcast or distributed.
Why are there different logos to denote captioned programs?

You will often see a logo in the corner of the screen at the beginning of a captioned program, but not all shows use the same one for trademark reasons. The "CC" (with or without the rounded rectangle surrounding it) is a generic logo, which can be used by any company. Camera-ready artwork for this logo is available from the Caption Center.

This logo, which looks like a comic strip´s speech balloon (a rounded rectangle with a small "tail" protruding below) is a registered service mark of the National Captioning Institute (NCI), and is only used for productions that are captioned by NCI.

Other logos are used for captioning in other countries and other languages as well. There is, for example, a new logo being used for Spanish-language captioning in Puerto Rico.
Is there a newsgroup or email list about captions?
There is a mailing list dedicated specifically to discussion of closed captioning and audio description, managed by Joe Clark. There are several Usenet newsgroups on related subjects that will have a captioning comment from time-to-time, but none are dedicated to the subject.
Contact information for the Access List:
CONTRIBUTIONS: Mail once only to access@maelstrom.stjohns.edu
TO UNSUBSCRIBE: Send "signoff access" (no quotes) to listserv@maelstrom.stjohns.edu
MESSAGES as DIGEST: Send "set access digest" to listserv@maelstrom.stjohns.edu
ARCHIVES: Send "index access" to listserv@maelstrom.stjohns.edu
PROBLEMS: Calmly report to owner-access@maelstrom.stjohns.edu
TO SUBSCRIBE: Send "subscribe access" to listserv@maelstrom.stjohns.edu
ON THE WEB: http://www.interlog.com/~joeclark/axxlist.html
Is there anything on CompuServe about captions?
There are two forums on CompuServe that contain sections relating to captioning.
CRForum (The Court Reporters Forum) section 4 covers captioning mostly from the realtime stenocaptioning point of view, although there is other captioning related discussion there from time to time.
The Deaf Forum (go DEAF) section 16 is about captioning from a more general perspective, obviously focused on the consumer point of view. This is a brand-new forum as of April 1997.
How do I communicate with deaf consumers?
Today´s electronic world offers many alternatives to ordinary voice-only telephone calls. Faxes and electronic mail are two easy and obvious ones. Most deaf people use a device called a TTY (also known as a TDD), which is a simple keyboard that connects to a telephone, often through an acoustic coupler. These are becoming increasingly common in public places like airports. When two people communicate via TTY, each sees what the other is typing.
The TTY communication standards are not the same as today´s computer modems, so a TTY can talk only to another TTY, or a special modem capable of handling Baudot.
If you will be offering captioning, and you wish to communicate with your deaf audience, you should really have a TTY. If, for some reason, that isn´t possible, then you can work through the relay services offered in every U.S. state and Canadian province, and throughout the U.K. and Australia, where an operator facilitates the conversation by typing on a TTY to one party and speaking to the other.