click here to skip directly to page content
Media Access Group  Versión en español
About Us Services and Products Research and Development Resources Get Involved

A wealth of information for producers, broadcasters, distributors, exhibitors, consumers, parents, and educators.


Information about captioning for video professionals

Volume 4 - Translating the Facts: Captioning Around the World

The Caption Center is fielding more questions than ever about captioning systems used around the world. As trading programming in the global marketplace becomes commonplace, television and video producers want to know whether captions produced for North American audiences will be able to follow their programs abroad. While there may not be a simple "yes" or "no" to that question, the issue doesn't have to be confusing. In this edition of TechFacts, The Caption Center passes along what we've learned about captioning systems used in other countries to (hopefully!) make your work easier.

While at least five incompatible technologies exist worldwide to broadcast captions (or subtitles as they are called in Europe and Australia, for simplicity, we will use the terms "captions" and "subtitles" interchangeably), two in particular dominate most of what is captioned-line-21 and World System Teletext (WST). Captions created using these technologies have a different appearance, use different amounts of bandwidth in the Vertical Blanking Interval (VBI), and require different consumer and professional hardware to create, encode and decode. Line-21 captioning, used in North America, is the most prevalent technology and is used on more than 200 hours of television programming each week.

Closed Captions- The NTSC System

Closed-caption data are carried within the normal broadcast signal. Specifically, they are recorded (or encoded) in line 21 of the VBI. Because line-21 closed captions are transmitted at a relatively slow rate (60 characters per second), they may be recorded and played back by the viewer at home using consumer-level VCRs. Additionally, the data pass through the entire broadcast transmission process and suffer very little degradation.

Line-21 captions appear on the television screen as white letters in a black box (although the use of color captions is allowed). The captions may appear in whole units of one, two, three or four rows (pop-on or paint-on captions, used for pre-produced programs), or may be a continually scrolling display of two, three or four rows of text (roll-up captions, created at the time of broadcast).

Pop-on and paint-on captions may be positioned nearly anywhere in the picture to indicate not only what is being said, but who is speaking. Roll-up captions usually appear in the lower third of the picture, although new FCC specifications allow them to be moved vertically to avoid covering important visual information, such as speaker ID's, which usually appear at the bottom of the screen.

The Television Decoder Circuitry Act (PL 101-431, which took effect on July 1, 1993), requires closed-caption decoding capability to be a built-in feature of all television sets 13" or larger manufactured for sale in the United States. Similar sets are shipped to Canada, where there are rules requiring broadcasters to carry captioned programs whenever available.

Teletext and Subtitling-A PAL System

In the European community, and in many other countries which use the PAL standard, viewers may see written information on their television screens through two different services: teletext and subtitling. While these services operate independently of one another, both rely on the use of the same decoder to be seen by viewers.

Teletext was developed in the early 1970s by engineers at the BBC as a means to make programming accessible to the deaf and hard-of-hearing communities. However, the newly developed technology made it possible to include many electronic "pages" of information in addition to subtitles, which in turn make the service useful to all viewers.

The teletext service consists of "pages" of information accessible by selecting special numbers from a television's remote-control unit. Various kinds of information-including news, sports, weather, finance, travel, TV/radio listings and games-are available at the touch of a button.

By 1984, as a result of continued development and use by countries other than the UK, the original teletext system evolved into what is known as World System Teletext (WST). Today, an enhanced version of WST is used by more than 30 countries worldwide, using decoders installed in television receivers which add little to the cost of the sets. The service is available in five "levels", each level offering increasingly sophisticated levels of enhancements and graphics. The higher levels require more complex decoding devices with progressively larger memories capable of storing great numbers of teletext pages; thus, receivers capable of decoding levels three, four and five may cost somewhat more than their less-sophisticated counterparts. In 1992, a total of 20 organizations representing 18 countries reported an audience of more than 30 million people with access to over 9,000 total pages of information.

Teletext data are digitally encoded in the VBI on lines 17 through 20, and are broadcast along with the normal video signal. Data are delivered at a rate of approximately 12 kilobytes per second. WST subtitles have a different appearance from line-21 captions, can be created in a variety of colors and may contain animated icons. However, because the data are broadcast on a number of lines at a fairly high data rate, teletext subtitles are not recordable on home VHS VCRs.

Line-21 type captions have recently been introduced for home video releases in the UK. Some British video stores now carry movies with line-21 captions re-encoded onto line 22 of the PAL VBI; these captions are visible only when the video is viewed through a special set-top decoder called the VideoCaption Reader(tm). This technology however, has not been introduced at the broadcast level. World System Teletext remains the method by which broadcasts are made accessible.

Because NTSC and PAL operate at different frames-per-second rates, captions created for one format are not immediately useable in another. If you are converting captioned video from NTSC to PAL for the home-video market (for use with the VideoCaption Reader(tm) decoding device in the UK), you must also convert the caption data to the new frame rate. If you are converting from NTSC to PAL for broadcast, you must convert your captions into World System Teletext format. Contact The Caption Center for information on these procedures.

Real Time

Real-time or live captions, created at the time of broadcast, are used extensively in the U.S. and Canada for news and sports programs. True real-time captioning takes advantage of a technology developed for court reporting, computer-aided real-time translation. A specially trained stenographer (called a stenocaptioner) listens to a program while it airs and types on an electronic stenotype keyboard. The data output of the keyboard is connected to a PC running translation software. The software converts the phonetic output from the stenotype keyboard into English and adds special captioning codes to the data stream before sending it to the encoding device.

For real-time captioning to be performed efficiently, the stenocaptioner must be careful to avoid "conflicts" in his or her stenographic writing. Common conflicts include homophones, words which sound the same but which are spelled differently such as "hear" and "here." Thus, to avoid transmitting potentially misleading or embarrassing captions, the stenocaptioner must learn to write each homophone in a distinct manner.

English real-time captioning, used in the United States, Canada, Britain and Australia is a well-developed technology. Real-time captioning software has also been developed for the French language and is used in Canada and France. However, French real-time captioning uses new software which is still evolving.

It is currently impossible to provide coherent, instantaneous translation from one language to another during real-time captioning (e.g. the stenocaptioner writes in English but the computer translates the data into French captions). As translation software becomes more sophisticated, simultaneous translation could eventually be incorporated into the real-time captioning process.

While stenographic writing is done in many languages other than English (including Italian, Spanish, Portuguese, Hebrew, Korean, Russian, Arabic and German) for courtroom and other uses, stenography is not currently used for real-time captioning in these languages. The problem of how these languages can be effectively written stenographically and then converted into captions has yet to be solved.

World Wide Formats

The following is a list of the video formats use around the world:

Afghanistan -- PAL
Albania -- PAL
Algeria -- PAL
Angola -- PAL
Antigua -- NTSC
Argentina -- PAL
Armenia -- SECAM
Aruba -- NTSC
Australia -- PAL
Austria -- PAL
Azerbaijan -- SECAM
Bahamas -- NTSC
Bahrain -- PAL
Bangladesh -- PAL
Barbados -- NTSC
Belarus -- SECAM
Belgium -- PAL
Belize -- NTSC
Benin -- SECAM
Bermuda -- NTSC
Bolivia -- NTSC
Bosnia -- PAL
Brazil -- PAL
Britain -- PAL
Brunei -- PAL
Bulgaria -- SECAM
Burundi -- SECAM
Cambodia -- SECAM
Cameroon -- PAL
Canada -- NTSC
Cape Verde -- PAL
Chad -- SECAM
Chile -- NTSC
China -- PAL
Colombia -- NTSC
Congo -- SECAM
Costa Rica -- NTSC
Croatia -- PAL
Cuba -- NTSC
Cyprus -- PAL
Czech Republic -- SECAM
Denmark -- PAL
Dominica -- NTSC
Dominican Rep. -- NTSC
Ecuador -- NTSC
Egypt -- SECAM
El Salvador -- NTSC
Equatorial Guinea -- SECAM
Estonia -- SECAM
Ethiopia -- PAL
Finland -- PAL
France -- SECAM
French Guiana -- SECAM
Georgia -- SECAM
Germany -- PAL/SECAM
Ghana -- PAL
Gibraltar -- PAL
Greece -- SECAM
Greenland -- PAL
Grenada -- NTSC
Guadeloupe -- SECAM
Guatemala -- NTSC
Guinea -- PAL
Haiti -- NTSC
Honduras -- NTSC
Hong Kong -- PAL
Hungary -- SECAM
Iceland -- PAL
India -- PAL
Indonesia -- PAL
Iran -- SECAM
Iraq -- SECAM
Ireland -- PAL
Israel -- PAL
Italy -- PAL
Ivory Coast -- SECAM
Jamaica -- NTSC
Japan -- NTSC
Jordan -- PAL
Kazakhstan -- SECAM
Kenya -- PAL
Kuwait -- PAL
Laos -- PAL
Latvia -- SECAM
Lebanon -- SECAM
Liberia -- PAL
Lithuania -- SECAM
Luxembourg -- PAL/SECAM
Madagascar -- SECAM
Malaysia -- PAL
Mali -- SECAM
Martinique -- SECAM
Monaco -- PAL/SECAM
Mongolia -- SECAM
Morocco -- SECAM
Mozambique -- PAL G
Namibia -- PAL
Nepal -- PAL
Netherlands -- PAL
New Guinea -- PAL
New Zealand -- PAL
Nicaragua -- NTSC
Niger -- SECAM
Nigeria -- PAL
North Korea -- PAL
Norway -- PAL
Pakistan -- PAL
Panama -- NTSC
Paraguay -- PAL
Peru -- NTSC
Philippines -- NTSC
Poland -- SECAM
Portugal -- PAL
Puerto Rico -- NTSC
Qatar -- PAL
Romania -- PAL
Russia -- SECAM
Saudi Arabia -- SECAM/PAL
Senegal -- SECAM
Serbia -- PAL
Sierra Leone -- PAL
Singapore -- PAL
Slovakia -- SECAM
Slovenia -- PAL
Somalia -- PAL
South Africa -- PAL
South Korea -- NTSC
Spain -- PAL
Sri Lanka -- PAL
St Kitts and Nevis -- NTSC
St. Lucia -- NTSC
Sudan -- PAL
Suriname -- NTSC
Sweden -- PAL
Switzerland -- PAL
Syria -- PAL/SECAM
Taiwan -- NTSC
Tajikistan -- SECAM
Tanzania -- PAL
Thailand -- PAL
Trinidad /wgbh/Tobago -- NTSC
Tunisia -- SECAM
Turkey -- PAL
Uganda -- PAL
Ukraine -- SECAM
Utd. Arab Emir. -- PAL
United States -- NTSC
Uruguay -- PAL
Uzbekistan -- SECAM
Venezuela -- NTSC
Vietnam -- SECAM
Virgin Islands -- NTSC
Yemen -- PAL/NTSC
Zaire -- SECAM
Zambia -- PAL
Zimbabwe -- PAL

To contact us for more information about captioning:

The Caption Center at WGBH
125 Western Avenue
Boston, MA 02134
(617) 300-3600 V/TTY
(617) 300-1020 fax

Los Angeles
300 E. Magnolia Blvd.
2nd Floor
Burbank, CA 91502
818 562-3344 voice
818 562-1919 TTY
818 562-3388 fax

New York
545 Fifth Ave.
Suite 609
New York, NY 10017
212 490-3677 voice
212 490-3688 fax

Caption Services Description Services NCAM