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Closed captioning
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Closed captioning is a term describing several systems developed to display text on a television or video screen to provide additional or interpretive information to viewers who wish to access it. Closed captions typically display a transcription of the audio portion of a program as it occurs (either verbatim or in edited form), sometimes including non-speech elements.
d "roll-up"-style open captions on some JumboTrons.]]
The term "closed" in closed captioning indicates that not all viewers see the captions — only those who choose to decode or activate them.
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Encyclopedia
Closed captioning is a term describing several systems developed to display text on a television or video screen to provide additional or interpretive information to viewers who wish to access it. Closed captions typically display a transcription of the audio portion of a program as it occurs (either verbatim or in edited form), sometimes including non-speech elements.
Terminology
used "roll-up"-style open captions on some JumboTrons.]]
The term "closed" in closed captioning indicates that not all viewers see the captions — only those who choose to decode or activate them. This distinguishes from "open captions" (sometimes called "burned-in" or "hardcoded" captions), which are visible to all viewers.
Most of the world does not distinguish captions from subtitles. In the United States and Canada, these terms do have different meanings, however: "subtitles" assume the viewer can hear but cannot understand the language or accent, or the speech is not entirely clear, so they only transcribe dialogue and some on-screen text. "Captions" aim to describe all significant audio content — spoken dialogue and non-speech information such as the identity of speakers and their manner of speaking — along with music or sound effects using words or symbols.
The United Kingdom, Ireland, and most other countries do not distinguish between subtitles and closed captions, and use "subtitles" as the general term — the equivalent of "captioning" is usually referred to as "Subtitles for the hard of hearing". Their presence is referenced on screen by notation which says "Subtitles" or previously "Subtitles 888" (the latter is in reference to the conventional teletext channel for captions).
Application
Most commonly, closed captions are used by deaf or hard of hearing individuals to assist comprehension. They can also be used as a tool by those learning to read, learning to speak a non-native language, or in an environment where the audio is difficult to hear or is intentionally muted. Captions can also be used by viewers who simply wish to read a transcript along with the program audio.
In the United States, the National Captioning Institute noted that 'English-as-a-second-language' (ESL) learners were the largest group buying decoders in the late 1980s and early 1990s before built-in decoders became a standard feature of US television sets. This suggested that the largest audience of closed captioning was people whose native language was not English. In the United Kingdom, of 7.5 million people using TV subtitles (closed captioning), 6 million have a hearing disability .
Closed captions are also used in public environments, such as bars, and restaurants, where patrons may not be able to hear over the background noise, or where multiple televisions are displaying different programs.
Television and video
For live programs, spoken words comprising the television program's soundtrack are transcribed by a human operator (a Speech-to-Text Reporter) using stenotype or stenomask type of machines, whose phonetic output is instantly translated into text by a computer and displayed on the screen. This technique was developed in the 1970s as an initiative of the BBC's Ceefax teletext service. In collaboration with the BBC, a university student took on the research project of writing the first phonetics-to-text conversion program for this purpose. Sometimes the captions of live broadcasts, like news bulletins, sports events, American Idol, and other live shows fall behind by a few seconds. This delay is because the machine does not know what the person is going to say next, so after the person on the show says the sentence, the captions appear. Automatic computer speech recognition now works well when trained to recognize a single voice, and so since 2003 the BBC does live subtitling by having someone re-speak what is being broadcast.
In some cases the transcript is available beforehand and captions are simply displayed during the program after being edited. For programs that have a mix of pre-prepared and live content, such as news bulletins, a combination of the above techniques is used.
For prerecorded programs, commercials, and home videos, audio is transcribed and captions are prepared, positioned, and timed in advance.
For all types of NTSC programming, captions are "encoded" into Line 21 of the vertical blanking interval – a part of the TV picture that sits just above the visible portion and is usually unseen. For ATSC (digital television) programming, three streams are encoded in the video: two are backward compatible Line 21 captions, and the third is a set of up to 63 additional caption streams encoded in EIA-708 format.
Captioning is transmitted and stored differently in PAL and SECAM countries, where teletext is used rather than Line 21, but the methods of preparation are similar. For home videotapes, a variation of the Line 21 system is used in PAL countries. Teletext captions can't be stored on a standard VHS tape (due to limited bandwidth), although they are available on S-VHS tapes and DVDs.
For older televisions, a set-top box or other decoder is usually required. In the US, since the passage of the Television Decoder Circuitry Act, manufacturers of most television receivers sold have been required to include closed captioning display capability. High-definition TV sets, receivers, and tuner cards are also covered, though the technical specifications are different. (High-definition display screens, as opposed to high-definition TVs, may lack captioning.) Canada has no similar law, but receives the same sets as the US in most cases.
There are three styles of Line 21 closed captioning:
- Roll-up or scroll-up or scrolling: The words appear from left to right, up to one line at a time; when a line is filled, the whole line scrolls up to make way for a new line, and the line on top is erased. The captions usually appear at the bottom of the screen, but can actually be placed anywhere to avoid covering graphics or action. This method is used for live events, where a sequential word-by-word captioning process is needed.
- Pop-on or pop-up or block: A caption appears anywhere on the screen as a whole, followed by another caption or no captions. This method is used for most pre-taped television and film programming.
- Paint-on: The caption, whether it be a single word or a line, appears on the screen letter-by-letter from left to right, but ends up as a stationary block like pop-on captions. Rarely used, it is most often seen in very first captions when little time is available to read the caption or in "overlay" captions added to an existing caption.
A single program may include scroll-up and pop-on captions (e.g., scroll-up for narration and pop-on for song lyrics). A musical note symbol (hash sign in UK, Ireland and Australia) is used to indicate song lyrics or background music. Generally, lyrics are preceded and followed by music notes (or hash signs), while song titles are bracketed like a sound effect. Standards vary from country to country and company to company.
For live programs, some soap operas, and other shows captioned using scroll-up, Line 21 caption text include the symbols '>>' to indicate a new speaker (the name of the new speaker sometimes appears as well), and '>>>' in news reports to identify a new story. In some cases, '>>' means one person is talking and '>>>' means two or more people are talking. Capitals are frequently used because many older home caption decoder fonts had no descenders for the lowercase letters g, j, p, q, and y, though virtually all modern TVs have caption character sets with descenders. Text can be italicized, among a few other style choices. Captions can be presented in different colors as well. Coloration is rarely used in North America, but can sometimes be seen on music videos on MTV or VH-1, and in the captioning's production credits. More often, coloration is used in the United Kingdom, Ireland, Australia and New Zealand for speaker differentiation.
There were many shortcomings in the original Line 21 specification from a typographic standpoint, since, for example, it lacked many of the characters required for captioning in languages other than English. Since that time, the core Line 21 character set has been expanded to include quite a few more characters, handling most requirements for languages common in North and South America such as French, Spanish, and Portuguese, though those extended characters are not required in all decoders and are thus unreliable in everyday use. The problem has been almost eliminated with the EIA-708 standard for digital television, which boasts a far more comprehensive character set.
Captions are often edited to make them easier to read and to reduce the amount of text displayed onscreen. This editing can be very minor, with only a few occasional unimportant missed lines, to severe, where virtually every line spoken by the actors is condensed. The measure used to guide this editing is words per minute, commonly varying from 180 to 300, depending on the type of program. Offensive words are also captioned, but if the program is censored for TV broadcast, the broadcaster might not have arranged for the captioning to be edited or censored also. The "TV Guardian", a television set top box, is available to parents who wish to censor offensive language of programs–the video signal is fed into the box and if it detects an offensive word in the captioning, the audio signal is bleeped or muted for that period of time.
Caption channels
The Line 21 data stream can consist of data from several data channels
multiplexed together. Field 1 has four data channels: two Captions (CC1, CC2)
and two Text (T1, T2). Field 2 has five additional data channels: two
Captions (CC3, CC4), two Text (T3, T4), and Extended Data Services (XDS). XDS
data structure is defined in EIA–608.
As CC1 and CC2 share bandwidth, if there is a lot of data in CC1, there will be little room for CC2 data. Similarly CC3 and CC4 share the second field of line 21. Since some early caption decoders supported only CC1 and CC2, captions in a second language were often placed in CC2. This led to bandwidth problems, however, and the current FCC recommendation is that bilingual programming should have the second caption language in CC3.
DVDs
NTSC DVDs may carry closed captions in the Line 21 format. They are sent to the TV by the player and can be displayed with a TV's built-in decoder or a set-top decoder as usual. Independent of Line 21, video DVDs may also carry captions as a bitmap overlay which can be turned on and off via the DVD player, just like subtitles. This type of captioning is usually carried in a subtitle track labeled either "English for the hearing impaired" or, more recently, "SDH" (Subtitled for the Deaf and Hard of hearing). On some DVDs, the Line 21 captions may contain the same text as the subtitles; on others, only the Line 21 captions include the additional non-speech information needed for deaf and hard of hearing viewers. European Region 2 DVDs do not carry Line 21 captions, and instead list the subtitle languages available - English is often listed twice, one as the representation of the dialogue alone, and a second subtitle set which carries additional 'sound' information for the deaf and hard of hearing audience. (Many deaf/HOH subtitle files on DVDs are reworkings of original teletext subtitle files.)
HD DVD and Blu-ray disc media cannot carry Line 21 closed captioning due to the design of High-Definition Multimedia Interface (HDMI) specifications that were designed to replace older analog and digital standards, such as VGA, S-Video, and DVI. Both Blu-ray disc and HD DVD can use either DVD bitmap subtitles (with extended definition) or 'advanced subtitles' to carry SDH type subtitling, the latter being an XML based textual format which includes font, styling and positioning information as well as a unicode representation of the text. Advanced subtitling can also include additional media accessibility features such as "descriptive audio".
Movies
There are several competing technologies used to provide captioning for movies in theaters. Just as with television captioning, they fall into two broad categories: open and closed. The definition of "closed" captioning in this context is a bit different from television, as it refers to any technology that allows some of the viewers to use captions while others in the same theater at the same time do not see captions.
Open captioning in a theater can be accomplished through burned-in captions, projected bitmaps, or (rarely) a display located above or below the movie screen. Typically, this display is a large LED sign.
Probably the best-known closed captioning option for theaters is the Rear Window Captioning System from the National Center for Accessible Media. Upon entering the theater, viewers requiring captions are given a panel of flat translucent glass or plastic on a gooseneck stalk, which can be mounted in front of the viewer's seat. In the back of the theater is an LED display that shows the captions in mirror image. The panel reflects the captions for the viewer, but is nearly invisible to surrounding patrons. The panel can be positioned so that the viewer watches the movie through the panel and captions appear either on or near the movie image. A company called Cinematic Captioning Systems has a similar reflective system called Bounce Back.
Digital Theater Systems, the company behind the DTS surround sound standard have a digital captioning device called the DTS-CSS or Cinema Subtitling System. It is a combination of a laser projector which places the captioning (words, sounds) anywhere on the screen and a thin playback device with a CD that holds many languages.
Other closed captioning technologies for movies include hand-held displays similar to a PDA (personal digital assistant); eyeglasses fitted with a prism over one lens; and projected bitmap captions. The PDA and eyeglass systems use a wireless transmitter to send the captions to the display device.
Video games
Closed captioning of video games is becoming more common. One of the first video games to feature true closed captioning was Zork Grand Inquisitor in 1997. Many games since then have at least offered subtitles for spoken dialog during cut scenes, and many include significant in-game dialog and sound effects in the captions as well; for example, with subtitles turned on in the Metal Gear Solid series of stealth games, not only are subtitles available during cut scenes, but any dialog spoken during real-time gameplay will be captioned as well, allowing players who can't hear the dialog to know what enemy guards are saying and when the main character has been detected. Also, in the video game Half-Life 2, when closed captions are activated, dialog and nearly all sound effects either made by the player or from other sources (e.g. gunfire, explosions) will be captioned.
Video games don't offer Line 21 captioning, decoded and displayed by the television itself but rather a built-in subtitle display, more akin to that of a DVD. The game systems themselves have no role in the captioning either: each game must have its subtitle display programmed individually.
Reid Kimball, a game designer who is hard of hearing, is attempting to educate game developers about closed captioning for games. Reid started the ] group to close caption games and serve as a research and development team to aid the industry. Kimball designed the Dynamic Closed Captioning system, writes articles, and speaks at developer conferences. Games[CC]'s first closed captioning project called Doom3[CC] was nominated for an award as for IGDA's Choice Awards 2006 show.
Theater
While opera houses have used captioning for their productions since 1983, live theater captioning has only recently begun appearing. Display techniques vary, with subtitles, surtitles and individual displays being used.
Telephones
A captioned telephone (also called captioned relay or Cap-Tel) is a telephone that displays real-time captions of the current conversation. The captions are typically displayed on a screen embedded into the telephone base.
Media monitoring services
In the United States especially, most media monitoring services capture and index closed captioning text from news and public affairs programs, allowing them to search the text for client references.
The use of closed captioning for television news monitoring was pioneered in 1993 by Tulsa-based NewsTrak of Oklahoma (later known as Broadcast News of Mid-America, acquired by video news release pioneer Medialink Worldwide Incorporated in 1997). US patent 7,009,657 describes a "method and system for the automatic collection and conditioning of closed caption text originating from multiple geographic locations" as used by news monitoring services.
HDTV interoperability issues
Americas
The US ATSC HDTV system originally specified two different kinds of closed captioning datastream standards—the original (available by Line 21) and another more modern version encoded in MPEG-2, the EIA-708 standard.
The US FCC mandates that broadcasters deliver (and generate, if necessary) both datastream formats. The Canadian CRTC has not mandated that broadcasters either broadcast both datastream formats or exclusively in one format.
Incompatibility issues with HDTV
Many viewers find that when they switch to an HDTV they are unable to view closed caption (CC)
information, even though the broadcaster is sending it and the TV is able to display it.
Originally, CC information was included in the picture ("line 21"), but there is no equivalent capability in
the HDTV 720p/1080i interconnects between the display and a "source".
A "source", in this case, can be a DVD player or an HD tuner (a cable box is an HD tuner).
When CC information is encoded in the MPEG-2 data stream, only the device that decodes the MPEG-2 data
(a source) has access to the closed caption information; there is no standard for transmitting
the CC information to an HD display separately.
Thus, if there is CC information, the source device needs to overlay the CC information on the picture prior to transmitting to the display over the interconnect.
Many source devices do not have the ability to overlay CC information, or controlling the CC overlay is extremely complicated.
For example, the Motorola DCT-5100 cable Set Top Box has the ability to decode CC information located on the mpg stream and overlay it on the picture, but turning CC on and off requires turning off the unit and going into a special setup menu (it is not on the standard configuration menu and it cannot be controlled using the remote).
Historically, DVD players and cable box tuners did not need to do this overlaying, they simply passed this information on to the TV,
and they are not mandated to perform this overlaying.
Many modern HDTVs can be directly connected to cables, but then they often cannot receive scrambled channels that the user is paying for.
Thus, the lack of a standard way of sending CC information between components, along with the lack of a
mandate to add this information to a picture, results in CC being unavailable to many hard-of-hearing and deaf users.
Europe
The European teletext systems are the source for closed captioning signals, thus when teletext is embedded into DVB-T or DVB-S the closed captioning signal is included. However, for DVB-T and DVB-S, it is not necessary for a teletext page signal to also be present (ITV1, for example, does not carry analogue teletext signals on Sky Digital, but does carry the embedded version, accessible from the "Services" menu of the receiver).
DTV standard captioning improvements
The EIA-708 specification provides for dramatically improved captioning
- An enhanced character set with more accented letters and non-Latin letters, and more special symbols
- Viewer-adjustable text size, allowing individuals to adjust their TVs to display small, normal, or large captions
- More text and background colors, including see-through backgrounds to optionally replace the big black block
- More text styles, including edged or drop-shadowed text rather than the letters on a solid background
- More text fonts, including monospaced and proportional spaced, serif and sans-serif, and some playful cursive fonts
- Higher bandwidth, to allow more data per minute of video
History
The first use of closed captioning on American television was on March 16, 1980. Sears had developed and sold the Telecaption adapter, a decoding unit that could be connected to a standard television set. According to the National Captioning Institute, the first programs seen with captioning that Sunday evening were the ABC Sunday Night Movie, Disney's Wonderful World on NBC, and Masterpiece Theatre on PBS. The captioned Disney feature, showing at 7:00 pm EST, was the film Son of Flubber, while the ABC movie at 9:00 EST was Semi-Tough.
On January 23rd, 1990, the Television Decoder Circuitry Act of 1990 was passed by US Congress. This Act gave the Federal Communications Commission (FCC) power to enact rules on the implementation of Closed Captioning. This Act required all analog television receivers with screens of at least 13 inches or greater, either sold or manufactured, to have the ability to display closed captioning in July 1, 1993. The FCC later placed the same requirements on digital television receivers due on July 1, 2002. All the TV programming distributors in the United States must provide closed caption for Spanish language video programming by January 1, 2010.
Close captioning in Australia
As a result of lobbying by Alexandra Hynes and Adam Salzer the government of Australia provided seed funding in 1981 for the establishment of the Australian Caption Centre (ACC) and the purchase of equipment. Captioning by the ACC commenced in 1982 and a further grant from the Australian government enabled the ACC to achieve and maintain financial self-sufficiency. The ACC, now known as Media Access Australia, sold its commercial captioning division to Red Bee Media in December 2005. Red Bee Media continues to provide captioning services to Australia today.
Logo
The current and most familiar logo for closed captioning is comprised of two Cs (for "closed captioned") inside a television screen. It was created by Jack Foley while he was a senior graphic designer at WGBH. Another logo, trademarked by the National Captioning Institute, was a speech balloon in the shape of a TV.
Bibliography
- The Closed Captioning Handbook, by Gary D. Robson (ISBN 0-240-80561-5)
- Alternative Realtime Careers: A Guide to Closed Captioning and CART for Court Reporters, by Gary D. Robson (ISBN 1-881859-51-7)
- Realtime Captioning... The VITAC Way, by Amy Bowlen and Kathy DiLorenzo (no ISBN)
See also
External links
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