Viewer FAQ

Frequently Asked Questions

The National Captioning Institute receives numerous inquiries from individuals regarding captioning and other media access issues. Here is information on the questions most often asked.

◦How does captioning work?
◦Why are there mistakes in the captioning?
◦Why are captions missing from programs? Why are they garbled?
◦Why does a program appear on one channel with captions and is repeated on another channel without captions?
◦Why are some home videos labeled as being captioned, but there are no captions on the movie?
◦Why do captions sometimes stop before the program is finished?
◦Why do captions sometimes disappear during commercial breaks?
◦Why don’t captions show up on my TV when I play a DVD?
◦Why can’t I see DVD captions on my computer?
◦Is closed captioning of television programming required?
◦How do I complain about closed captioning problems?
◦Is closed captioning available for digital television?
◦Will digital-to-analog converter boxes used to convert over-the-air digital TV broadcasts for viewing on analog TV sets also convert digital closed captions?
◦How do I access descriptions on my TV?

How does captioning work?

There are three main types of captioning: off-line for prerecorded programming; real-time for live programming; and live display.

Off-line captions are used for prerecorded programs and are prepared before the programs are shown on television. An off-line captioner views a tape of the program and types the dialogue and sound effects on a standard keyboard into a computer equipped with special captioning software. Captions are time-coded to correspond to the same time code on the videotape where the spoken dialogue occurs, so several lines of captions appear at once in synchronization with the dialogue. The captions are stored in a computer file and undergo a process called encoding, which merges the captions and a copy of the original master tape to produce a captioned submaster tape. The tape is returned to the program source (the network, cable network, producer) and is used when the program is aired. A captioned submaster tape is also used for producing home videos.

Real-time captioning is used for live programs such as news and sports. Highly skilled captioners watch (or just listen to) a live television program and phonetically stroke words on a stenograph machine (like court reporters use) at speeds of over 225 words per minute. The steno machine is nothing like a regular computer keyboard–it does not have a key for every letter. Syllables are entered by pressing several keys at once, like a chord on a piano. A computer connected to the steno machine, and containing a special dictionary, converts the phonetic shorthand into captions. The captions are sent back to the broadcaster over telephone lines and are automatically added to the television broadcast signal. They are displayed line by line, two to three seconds after the words are spoken. This style is called “roll-up” captioning.

Live display captioning is used when a program script is available beforehand for a live event broadcast. It is also used for taped programs, like daytime dramas, when there is not enough time to use the off-line captioning process. Before the broadcast, caption operators enter the information and store the words on a computer disk. During the broadcast, the file is called up from the disk, and the captions are sent to the broadcaster over telephone lines and added to the television broadcast signal by a caption operator one line at a time. With live display captioning, the words are displayed in the roll-up style as they are being spoken. Sometimes, it is necessary to shift to real-time captioning if last minute changes are made in the broadcast.

(Back to Top of Page)

Why are there mistakes in the captioning?

There are many companies providing captioning services, and captioning quality can vary among the different companies. Often, errors occur because of technical problems in transmitting and receiving the captions.

Misspellings on a prerecorded program are usually caused by human error. NCI has systems in place to review captions twice before they are released to the client.

Real-time captioning poses unique challenges. Because the captions are displayed instantly, there is no time to proofread them or correct an error. To avoid mistakes, captioners spend a considerable amount of time researching and entering into the computer any words that might come up on a particular program, such as players’ names in a baseball game or geographical references that might appear on the news. For instance, if a captioner does not have the word “mosquito” in his/her computer dictionary, the computer may not recognize the syllables as a word, and might just print them out as “moss key toe.” Captioners must also make the computer distinguish among words that sound the same, like “to,” “too” and “two”.

Mistakes can be caused by the captioner hitting wrong keys or by the computer incorrectly translating the phonetic code. Spoken words that are muffled or hard to understand can lead to captioning errors, too. And new captioners, although they have had years of stenographic training, still need actual broadcast experience to bring their skills to the highest level.

Spur-of-the-moment editing is needed if a word is spoken that the captioner knows the computer will not translate correctly or if the dialogue is too fast to take down verbatim. Captions may even fall behind as they are created because there is a limit on how fast the television set can show them. Then it appears as if the captions are not keeping pace with the dialogue.

NCI’s standard of accuracy for live captioning is a minimum of 98%, though usually exceeds 99.3%. If a captioner writes approximately 7,000 words in an hour-long program, at an average of two syllables per word that amounts to 14,000 key strokes. Not many people can simultaneously listen and reproduce what they’ve just heard at a high rate of speed for an hour or more.

Some problems may occur during the transmission and reception of the television signal. Captions are a delicate part of the signal and any interference may cause them to become garbled or to disappear. There are many opportunities for the captions to encounter interference in the process of being broadcast, starting with the phone lines that transmit the captions from NCI to the broadcaster all the way to your own equipment at home, so there are often technical reasons for poor or missing captions. Even the quality of the equipment can affect whether the captions are displayed accurately. NCI has program monitors checking to be sure that the captions are correct when they are sent to the broadcaster.

(Back to Top of Page)

Why are captions missing from programs? Why are they garbled?

Captioning problems can occur for a variety of reasons and the problems can stem from different sources depending on the type of broadcast, such as network, syndication or cable. The captions are delicate, and they travel from the caption company to the broadcaster through the phone lines, go through the encoding equipment, then get bounced to the satellites, local stations and cable companies, and finally pass through the home receiver, so there are many opportunities for them to encounter interference that impairs their quality.

Since the caption data is inserted directly into the television transmission signal, anything blocking the signal path will cause the captions to become garbled or disappear altogether. A weak transmission of a television signal, poor reception of the television signal as it travels into the home, or cable problems in the home can also garble captions or cause white boxes to appear within captions. Words with pairs of letters missing, such as “I msd y” for “I missed you” does not result from poor quality captioning, but is an indicator of a reception or television station equipment problem. High quality equipment has a greater tolerance for error and is better able to decode the captions in spite of interference.

A related problem may occur when a cable company leaves off some of the “unused” lines of the TV signal. If they do this, then sometimes the caption decoder chip can’t find the line where the captions are, so the captions don’t appear.

(Back to Top of Page)

Why does a program appear on one channel with captions and is repeated on another channel without captions?

Once a program is captioned, then the captions should stay with that program for rebroadcast-unless the program has been edited. Any changes to a program will affect the captions. In some cases, a captioned program is aired on network television and later rebroadcast on cable. However, the cable version may appear without captions. In this case, the new program provider altered the program, perhaps to fit it within a specific time slot or to add commercial breaks. This adjustment changed the time-coded caption data, preventing the captions from appearing. To correct this problem for future broadcasts, the programmer must have the captions reformatted (or edited and re-timed).

It also is possible that the new program provider received uncaptioned master videotape and was not aware that a captioned version was available. This may be the case with some uncaptioned home videos of programs that were broadcast with captions. When NCI learns that a program or series that was previously captioned will be re-broadcast or released for home video distribution, we remind the distributor to reformat the captions so the repeat version of the program will be captioned.

(Back to Top of Page)

Why are some home videos labeled as being captioned, but there are no captions on the movie?

If there are no captions on a video, the master tape used to make the copies may not have had captions. The studios make thousands of copies at different facilities, and maybe one of the facilities did not use a captioned master tape. It’s also possible that the captions may have been accidentally stripped off due to a technical problem in reproducing the tape.

Equipment problems and poor quality equipment can produce errors in the captions as they are being displayed. The caption decoder chip in some equipment has very little room for error, so if the timing is off a little bit, the chip can’t find the captions. Perhaps there is a tension problem in which the tension on the tape in your VCR does not match the tension used when recording the tape, which affects the ability of the decoder to find and decode the captions. Sometimes a tape will seem to have very poor captions (garbled or missing or white boxes) when played on one VCR, but the captions are much improved when played on a different VCR. The quality of the tape also plays a role in caption quality, and poor quality tape will often cause errors that are not in the actual captions.

If a consumer receives a videotape with missing captions, the tape should be returned to the place where it was rented or purchased. The home video distributor also should be informed that the captions were missing.

(Back to Top of Page)

Why do captions sometimes stop before the program is finished?

Some live events, such as sports, do not have a clearly pre-determined ending time. They may be scheduled to end before 11:00 p.m., for instance, but they go into overtime and last beyond 11:00 p.m. If the person who is captioning that event is scheduled to caption another show at 11:00 p.m., such as the news on another channel, he or she must stop working on the sports event and switch to the news, thus ending the captioning of the sports event. NCI takes care in scheduling its captioners to prevent this from happening.

(Back to Top of Page)

Why do captions sometimes disappear during commercial breaks?

When a program is being captioned live and reaches a commercial break or the end of the program, the captioner must send a command to enable the encoder that is processing the captions to accept other data. If the captioner neglects to send this enabling command when finishing the captioning of a segment or program, the captions on the next commercial or program will not be able to access the encoder, and will not appear. The technical staff at the broadcast site must be alert for this situation. Also, the commercials themselves might not be captioned.

(Back to Top of Page)

Why don’t captions show up on my TV when I play a DVD?

The problem may be with the DVD player, the connector, or the DVD. Some DVD players don’t support closed captions.

The problem could also be caused by the cable or cables used to connect the DVD player to the TV. New high-end cables designed to provide the highest quality picture and sound cannot carry caption data from the source, such as a DVD player, to the caption decoder in the TV. These cables include HDMI (High Definition Mutimedia Interface) and component connectors labeled RGB or YpbPr. Connectors that deliver lower quality video need to be used to pass through captioning to the TV decoder. These connectors include the standard composite cable (usually includes a yellow RCA pin connector for video) and S-Video, though S-Video cables will not pass through captions with all brands of DVD players and TV sets. It is unlikely that a DVD player built into a digital TV will pass through captions because the unit most likely contains an internal HDMI connector between the DVD player and the TV display.

Another possibility is that the DVD producer chose to use English subtitles instead of captions. Subtitles do not need to go through the decoder to be displayed the way captions do. Subtitles are turned on and off using a button on the DVD player remote or by using the remote to select subtitles from an option menu.

(Back to Top of Page)

Why can’t I see DVD captions on my computer?

Most computers do not have the caption decoding circuitry needed to display closed captions.

(Back to Top of Page)

Is closed captioning of television programming required?

Congress passed The Telecommunications Act of 1996, a law requiring video program distributors (cable operators, broadcasters, and satellite distributors) to phase in closed captioning of their television programs. The law does not require captioning of VHS or DVD home video releases, video games, or videos on the Internet.

The Federal Communications Commission (FCC) prescribed rules and implementation schedules for the captioning of video programming for television broadcasts. They established an eight-year transition period starting on January 1, 1998 for the captioning of new video programming in English. As of the end of the transition period, January 1, 2006, 100% of all non-exempt new programs must be captioned.

For programming first exhibited before January 1, 1998 (“pre-rule programming”), the FCC established a ten-year transition period. The FCC ruled that at least 30% of a channel’s pre-rule programming be provided with captions beginning on January 1, 2003, and that at least 75% of such programming be captioned by the end of the transition period in 2008.

Because captioning is fairly new to Spanish language program providers, the FCC has provided a longer time period for compliance by these programmers. All new Spanish language programming that was first shown after January 1, 1998, must be captioned by 2010. For Spanish language programming first shown before January 1, 1998, 75% must be captioned by 2012.

Some exemptions are allowed under the FCC rules, such as non-English or nonvocal programming, some local programming, commercials, and public service announcements. Small stations and new stations are exempt.

The regulations require program distributors, such as cable and satellite companies, to pass through to the viewers all the captions that are on the programs they distribute; they may not interrupt or strip the captions.

Visit for additional information.

(Back to Top of Page)

How can I complain about closed captioning problems?

The Federal Communications Commission (FCC) has issued rules about closed captioning, and they have established a complaint process. Before you proceed, be sure your own equipment is in good working order.

You should first complain in writing to your programming distributor (i.e., your cable or satellite TV service, or the TV station if you do not pay for cable, satellite, or another subscription video service). If you are paying for cable or satellite television service, your provider is responsible for resolving any captioning problems even if the problems might be in the program feed they are receiving. Check your provider’s Website about who to contact regarding captioning problems or look up the contact using this Website. Complaints that are polite and specific with complete details are the most effective.

Keep a record of your complaint. If the problem is not resolved, then you can file a complaint with the FCC. There are a number of rules for filing complaints, so you should read and follow them to be sure your complaint will be considered. Your complaint has to be very specific (date, time, stations affected, etc.). Click on this link to see the FCC’s closed captioning guide, which includes information about filing closed captioning complaints. NOTE: The National Association of the Deaf (NAD) suggests that you submit your complaint to the FCC at the same time as you notify your service provider so that the FCC gets a better understanding of the types of problems people are having with captioning.

(Back to Top of Page)

Is closed captioning available for digital television?

The television industry is in the process of converting from traditional analog TV to digital TV (DTV), which also includes high definition television (HDTV). A televison consists of a display and a tuner for receiving TV signals. For DTV or HDTV, a digital tuner is either built into the TV display or included in a separate set top box (STB), usually provided by a cable or satellite TV company. All TVs with a screen size of 13 inches or larger and a built-in tuner along with all STBs must include the ability to decode and display caption data embedded in digital TV signals. If you are using a digital STB to select the channel you are watching, then you must use the remote control or on-screen menu for that device to control the display of captions for any program that is available with captions.

For more information about DTV click on the following links.

FCC – Digital TV –

Consumer Electronics Association – Using Closed Captions in the Digital TV Age

(Back to Top of Page)

Will digital-to-analog converter boxes used to convert over-the-air digital TV broadcasts for viewing on analog TV sets also convert digital closed captioning?

Yes. FCC rules require that digital-to-analog converter boxes be able to convert over-the-air digital closed captioning so that analog TV sets can decode and display them. Most coverter boxes also have the capability to decode and display the captions themselves, meaning that the viewer could use the settings on the converter box or a button on the converter box remote to turn on the captions. For more information, go to or

(Back to Top of Page)

How do I access descriptions on my TV?

Descriptions of a program’s visual elements added to the standard sound track of some programs provide access to television and other video programming for people who are blind or have low vision.

To access descriptions, you need either a TV or VCR equipped with stereo and the Secondary Audio Programming (SAP) capability — all of which became standard after 1992 — or a stand-alone SAP receiver. If you’re using a TV or VCR, simply activate the SAP feature through the TV’s remote control or on-screen menu. Sometimes it’s labeled “MTS,” (Multi-channel Television Sound), which provides a choice of SAP, mono or stereo. If you have a digital TV or digital set-top box, the on-screen MTS audio options might show as English Stereo and Spanish Mono, which could be either Spanish audio or the English described audio depending on which option is available for a particular program. If you have difficulty locating this audio option feature, consult the equipment manual or contact the manufacturer. If you’re using a stand-alone SAP receiver, which functions very much like a radio, simply tune it to the channel that broadcasts the description soundtrack (may be used in addition to a TV or for audio only). Pre-tuned and adjustable SAP receivers may be purchased from FM Atlas at 218-879-7676.

If you are using a digital set top box (STB) from a cable or satellite TV provider with a digital TV, use the STB’s remote or on-screen menu to select the described audio source.

If you are using a digital-to-analog coverter box to watch digital broadcasts on an analog TV, you should be able to use either the remote that comes with the coverter box or the TV to access the SAP option. See the following FCC Advisories for more information. or

Descriptions are only available on a limited number of programs. Check local listings and network or local station Web sites. Keep in mind that all of this is still new to commercial broadcasters and cable networks, so even if you activate the SAP feature, you may encounter difficulties: 1) your local television station must be equipped to pass along the SAP signal; and 2) if you have cable or satellite access to programming, those companies must also pass along the SAP signal.

(Back to Top of Page)