Archiving Teletext

Picture This...

Someone in the 1980s, let's say 1985, records their favorite program from CBS, NBC, or TBS onto their choice of videotape (Betamax or VHS). After the program, they might use that same tape to record other programs, but once it's full, onto the shelf it goes. What this person might not have realized is that besides recording a TV program, they recorded something else that they couldn't visibly see on their TV screen, something that has seemingly become forgotten in North America: teletext.

Someone in the 1980s, let's say 1985, records their favorite program from CBS, NBC, or TBS onto their choice of videotape (Betamax or VHS). After the program, they might use that same tape to record other programs, but once it's full, onto the shelf it goes. What this person might not have realized is that besides recording a TV program, they recorded something else that they couldn't visibly see on their TV screen, something that has seemingly become forgotten here in North America: teletext.

Wait... Really?

It's true! Many people will have transferred a videotape in their lives, whether it's a home movie or a TV broadcast. I (the creator of this site) have done my fair share of videotape transfers going back to 2011. Like most people who have transferred videotape, I assumed the only content on the tape was the programming content I was transferring. It wasn't until around 2025 when I realized just how much I was missing by transferring videotape the usual conventional way, which for me was transferring to a DVD recorder, then importing the files onto my computer.

How, Though?

In the days of analog TV, there was an unused portion of the video signal called the vertical blanking interval (VBI). TVs normally do not show the VBI, so many don't know it's there. The VBI can hold things such as CEA-608 closed captioning (sometimes called Line 21 captions since these captions were on Line 21 of the VBI), vertical interval timecode (VITC), test signals, and even data. I'm not going to go into the specifics of what the VBI is, so I'll link the Wikipedia article for that. There's also a great lecture video on YouTube uploaded in 2022 by the U.K.'s Centre for Computing History that discusses what teletext is and how it can be recovered from old videotapes.

In the days of analog TV, there was an unused portion of the video signal called the vertical blanking interval (VBI). TVs normally do not show the VBI, so many don't know it's there. The VBI can hold things such as C E A dash six oh eight closed captioning (sometimes called Line 21 captions since these captions were on Line 21 of the VBI), vertical interval timecode (VITC), test signals, and even data. I'm not going to go into the specifics of what the VBI is, so I'll link the Wikipedia article for that. There's also a great lecture video on YouTube uploaded in 2022 by the U.K.'s Centre for Computing History that discusses what teletext is and how it can be recovered from old videotapes.

When a program was recorded to videotape, not only was the program itself recorded, but the VBI was recorded as well. Whatever was present in the VBI at the time of the recording was preserved in the videotaped recording. This means that, if recording a program with Line 21 captions, those captions remained in the recording. Moreover, this means that if someone recorded a network with a teletext feed, such as TBS, the teletext was also preserved in the VBI.

Some high-profile teletext services include CBS's ExtraVision, NBC's NBC Teletext, and Keyfax/Electra, the previous two being included in TBS's VBI, with Electra replacing Keyfax in the mid 1980s. ExtraVision and NBC Teletext used a standard known as the North American Broadcast Teletext Standard (NABTS), while Keyfax/Electra use the pre-existing World System Teletext (WST) standard.

Some high-profile teletext services include CBS ExtraVision, NBC's NBC Teletext, and Keyfax/Electra, the previous two being included in TBS's VBI, with Electra replacing Keyfax in the >mid 1980s. ExtraVision and NBC Teletext used a standard known as the North American Broadcast Teletext Standard (N A B T S), while Keyfax/Electra use the pre-existing World System Teletext (WST) standard.

Wait, What Are Those?

Those are the different standards used here in North America; Europe only used the WST standard. A big difference between the two standards concerned the graphical capabilities. WST relied heavily on text, NABTS relied on both text and graphics. To that point, the graphical capabilities of NABTS services exceeded WST services.

Those are the different standards used here in North America; Europe only used the WST standard. A big difference between the two standards concerned the graphical capabilities. WST relied heavily on text, while the N A B T Srelied on both text and graphics. To that point, the graphical capabilities of N A B T S services exceeded WST services.

NABTSN A B T S

WST

To learn more about teletext in North America, including some differences between NABTS and WST, give J.B. Crawford's great newsletter, "Teletext in North America" a read.

To learn more about teletext in North America, including some differences between N A B T S and WST, give J.B Crawford's great newsletter, "Teletext in North America" a read.

Do Capture Cards Work?

Yes, some capture cards are capable of capturing the VBI and therefore the teletext data. An up-to-date list of capable devices, as well as instructions for capturing the raw data is available from the Analog Video Wiki's page on Capturing VBI signals.

Yes, some capture cards are capable of capturing the VBI and therefore the teletext data. An up-to-date list of capable devices, as well as instructions for capturing the raw data is available from the Analog Video Wiki's page on Capturing VBI signals.

How Do I Get Started?

The simplest method for capturing raw VBI data from the playback of videotape recordings is by using an appropriate capture card as described in the Analog Video Wiki's page on Capturing VBI signals. It is important with this capture method that the playback VCR be connected directly to the capture device and not passed through other equipment such as DVD recorders, as these other devices can alter or remove the VBI data you are attempting to capture.

A more advanced way to preserve the VBI when transferring videotape is using the FM RF capture method and the VHS-Decode software. This method insures preservation of the entire video signal, including all lines of the VBI where teletext data is found. Detailed information on this method of videotape capture is available on the VHS-Decode wiki.

Once you have archived some VBI data with teletext, the decoding is performed using a software tool called Decode-Orc. This software, though part of the suite of software tools related to LD-Decode and VHS-Decode, can be used to decode VBI data captured either with the simple, conventional method or the advanced FM RF capture method. Most importantly for North American teletext archiving, Decode-Orc is currently the only software decoder that supports both NABTS and WST standards. The teletext part of the software, while officially released, is still under development. As more members of the tape archiving community use the software and discover bugs and other issues, the software will improve over time.

Once you have archived some VBI data with teletext, the decoding is performed using a software tool called Decode-Orc. This software, though part of the suite of software tools related to LD-Decode and VHS-Decode, can be used to decode VBI data captured either with the simple, conventional method or the advanced FM RF capture method. Most importantly for North American teletext archiving, Decode-Orc is currently the only software decoder that supports both N A B T S and WST standards. The teletext part of the software, while officially released, is still under development. As more members of the tape archiving community use the software and discover bugs and other issues, the software will improve over time.

We also want to note something else. Capturing the VBI not only captures the teletext stream, but it also captures Line 21, used for closed captioning. Line 21 was also sometimes used for text-based services, services that are purely text-based. Examples of these services include ABC's Program Listing Update Service (PLUS) and Kentucky Educational Television's (KET) AgText. These services can be decoded using this fork of the CC-Decoder project, just be sure to specify the output as HTML.

Will All My Tapes Have Teletext?

First, to note, CBS, NBC, and TBS were the only national broadcasters to have teletext services, so recordings from those networks made within the ranges below will often have teletext. Note that this is not a definite list. As we discover more services and networks, this list will be updated accordingly.

DaTaVizion

Format: WST

Networks: KICU-TV (San Jose, CA) | Discovery Channel

Date Range: Appx. mid-1980s – Appx. 1989

Electra

Format: WST

Networks: TBS | Various local stations (see below this list)

Date Range (Local): June 23, 1983 – June 11, 1993

Date Range (National): January 1, 1985 – June 11, 1993

ExtraVision

Format: NABTS

Network: CBS

Date Range: April 4, 1983 – Appx. 1992

Keyfax

Format: WST

Network: WFLD-TV (Chicago, IL) | WTBS (SuperStation)

Date Range: Appx. 1982 – Appx. mid-1985

NBC Teletext

Format: NABTS

Network: NBC

Date Range: May 16, 1983 – Appx. late-1985

SSS Teletext

Format: WST

Network: TBS

Date Range: June 11, 1993 – Appx. 1997

Virtext

Format: WST

Network:WGN-TV (Chicago, IL)

Date Range: 1980s – Appx. late-1980s

• DataVision (Discovery Channel / KCIU-TV): approximately the mid 1980s to appropriately 1989
• Electra (TBS): January 1, 1985 to June 11, 1993. The local version started on June 23, 1983.
• ExtraVision (CBS): April 4, 1983 to approximately 1992
• Keyfax (TBS): approximately 1982 to approximately mid 1985
• NBC Teletext (NBC): May 16, 1983 to approximately late 1985
• SSS Teletext (TBS): June 11, 1993 to approximately 1997
• Virtext (TBS): 1980s to approximately the late 1990s

There were four stations that broadcast Electra over the air. These are listed below. Additionally, KTTV (Los Angeles, CA) had a WST service known as MetroText during the 1984 Summer Olympics and also broadcast Electra pages.

• WKRC-TV (Cincinnati, OH), where Electra originated
• WTVN-TV (Columbus, OH), which was co-owned with WKRC by Taft Broadcasting
• KOVR (Stockton-Sacramento, CA)
• WIHT (Ann Arbor, MI), owned by SSS (Satellite Syndicated Systems). This was also the company that uplinked WTBS for cable.

Some public broadcasting stations broadcast WST teletext to provide agricultural information. Most notable was Infotext, provided by the University of Wisconsin-Extension and aired on Wisconsin Public Television and WMVS (Milwaukee, WI). A version of Infotext, along with a magazine called DaTaVizion which consisted of features, was broadcast with the Discovery Channel on cable by a San José, California, firm known as Data T.V. Inc. (Data T.V. also broadcast this service on KICU in San José circa 1987.) DakotaText aired on South Dakota Public Television stations from 1987 to 1995. There was also a teletext service trial in Utah, though it is not clear if it ever entered regular service or what standard was used.

Some public broadcasting stations broadcast WST teletext to provide agricultural information. Most notable was InfoText, provided by the University of Wisconsin-Extension and aired on Wisconsin Public Television and WMVS (Milwaukee, WI). A version of InfoText, along with a magazine called DataVision which consisted of features, was broadcast with the Discovery Channel on cable by a San José, California, firm known as Data TV Incorporated (Data TV also broadcast this service on KICU in San José circa 1987.) DakotaText aired on South Dakota Public Television stations from 1987 to 1995. There was also a teletext service trial in Utah, though it is not clear if it ever entered regular service or what standard was used.

International TeleText Communications of Sunnyvale, California, broadcast WST teletext information, principally news and stock quotes, beginning in the late 1980s from KICU San José (apparently replacing Data T.V.) and KHSC in the Los Angeles market. In 1993, ITC began to air teletext on all the Silver King Broadcasting stations (which aired the Home Shopping Network). These are listed below (they may not have done this for a long period of time before changing technologies).

International TeleText Communications of Sunnyvale, California, broadcast WST teletext information, principally news and stock quotes, beginning in the late 1980s from KICU San José (apparently replacing Data TV) and KHSC in the Los Angeles market. In 1993, ITC began to air teletext on all the Silver King Broadcasting stations (which aired the Home Shopping Network). These are listed below (they may not have done this for a long period of time before changing technologies).

• WBHS 50 (Tampa, FL)
• WEHS 60 (Chicago, IL)
• WHSE 68 & WHSI 67 (New York, NY and Long Island, NY)
• WHSH 66 (Boston, MA)
• WHSP 65 (Philadelphia, PA)
• WHSW 24 (Baltimore, MD - Washington, D.C.)
• WQHS 61 (Cleveland, OH)
• WYHS 69 (Miami, FL)
• KHSX 49 (Dallas, TX)
• KHSH 67 (Houston, TX)

Electra ceased on June 11, 1993. SSS/Tempo continued to broadcast teletext for its Tempo stock quote service and to support several firms that used teletext for data transmission of sports betting lines: All World Data Communications of The Woodlands, Texas, which used substitution ciphered pages; and SportScreen, produced by Entertainment Technologies Inc. of Las Vegas.

With TBS being a national service, it's safe to assume that almost any TBS recording from appx. 1982 to appx. 1993 will have teletext. (It may not if recorded in the Atlanta area, because Electra was distributed by the group that uplinked (W)TBS for cable companies nationwide. If you see channel 17 references in promotions, don't expect teletext!) However, CBS and NBC are different; before assuming that any recording of programming from those two networks will automatically have teletext, there are a couple of important things to note.

With TBS being a national service, it's safe to assume that almost any TBS recording from approximately 1982 to approximately 1993 will have teletext. (It may not if recorded in the Atlanta area, because Electra was distributed by the group that uplinked WTBS/TBS for cable companies nationwide. If you see channel 17 references in promotions, don't expect teletext!) However, CBS and NBC are different; before assuming that any recording of programming from those two networks will automatically have teletext, there are a couple of important things to note.

1.) Local vs. National Programming

The national broadcast networks (ABC, CBS, FOX, NBC) do not provide a 24/7 schedule of programming. To make up for time when no programming from the network is being aired, affiliates fill these time slots with locally produced content, nationally syndicated content, and local news coverage. Even during network programming, stations insert local commercials and promotions.

It is our experience that most stations did not "bridge" the network VBI during local time and thus only broadcast teletext when carrying a network feed. Even during prime time, teletext data would drop off every time a station aired a local promo, commercial, or plug for its local news.

What this means is that the teletext services from CBS and NBC were not always being broadcast at all times by most affiliates while they were on air. Teletext data was relayed during all broadcast hours on CBS owned & operated (O&O) stations, stations that the broadcast networks, as the term suggests, owned and operated. NBC O&O stations did not provide this constant relay of teletext data as evidenced by the recordings we have so far examined. The five CBS O&Os of the 1980s were WCBS-TV New York, KNXT/KCBS-TV Los Angeles, WBBM-TV Chicago, WCAU-TV Philadelphia, and KMOX-TV St. Louis. These stations likely had consistent teletext information, as did the three affiliates that broadcast local Extravision: WBTV Charlotte, WIVB-TV Buffalo, and KSL-TV Salt Lake City. Note that CBS sold KMOX-TV in 1986, at which time it became KMOV, so we do not know if it continued to bridge the VBI. We list these stations on the homepage as we are looking for more samples from these stations.

What this means is that the teletext services from CBS and NBC were not always being broadcast at all times by most affiliates while they were on air. Teletext data was relayed during all broadcast hours on CBS owned & operated (O&O) stations, stations that the broadcast networks, as the term suggests, owned and operated. NBC O&O stations did not provide this constant relay of teletext data as evidenced by the recordings we have so far examined. The five CBS O&Os of the 1980s were WCBS-TV New York, KNXT/KCBS-TV Los Angeles, WBBM-TV Chicago, WCAU-TV Philadelphia, and KMOX-TV Saint Louis. These stations likely had consistent teletext information, as did the three affiliates that broadcast local Extravision: WBTV Charlotte, WIVB-TV Buffalo, and KSL-TV Salt Lake City. Note that CBS sold KMOX-TV in 1986, at which time it became KMOV, so we do not know if it continued to bridge the VBI. We list these stations on the homepage as we are looking for more samples from these stations.

2.) Local Affiliate Usage of the VBI

Not all local affiliates are alike. Differences in operating practices as well as the type of equipment used at each station can affect what signals ended up in each station's VBI. The images below illustrate how this can impact the teletext recovery process. These images are enlargements of the VBI taken from recordings of two different CBS affiliates of the 1980s: WHAS-TV, Louisville, KY and WBBM-TV, Chicago, IL.

To make spotting the difference clearer, outlines and labels have been added to each image to delineate different signals. In the WHAS-TV VBI, there are only five lines of teletext data when there should be eight for CBS ExtraVision. This is because WHAS-TV inserted three lines of VITS (vertical interval test signals) over top of three of the eight teletext lines. The VBI image from WBBM-TV shows that they were carrying the full eight lines of CBS ExtraVision teletext data.

The consequence of this is that the teletext data on the WHAS-TV recording does not represent the full data stream because it is missing three lines. This means that the complete ExtraVision magazine cannot be recovered from the WHAS-TV recording and that there are likely to be more corrupted or garbled pages in the recovery because the data is incomplete. In contrast, the CBS ExtraVision data in the WBBM-TV recording is complete and so the full magazine is recoverable.

Partial recoveries, while not ideal, are still better than no recovery at all. Unfortunately, some CBS and NBC affiliates either completely stripped or did not pass teletext data at all making recovery impossible from recordings of those stations. For an in-progress list of stations that stripped or altered the network teletext lines, visit this page.

How Can I Find Out?

The quickest and simplest way to determine whether a recording has teletext data in the VBI is to capture a short section of the recording's VBI using one of the capture devices listed on the Analog Video Wiki's page on Capturing VBI signals. The short VBI capture can then be examined using ffplay or Decode-Orc to see if teletext data is present. If you see at least several lines containing dense digital bits, you may have teletext! For text services, simply export all Line 21 data using CC-Decoder and, after the export completes, look for filenames that include "T1" or "T2". Another way is to simply conenct your VCR to a TV that still has composite inputs, then check the TEXT1-TEXT4 channels by navigating through your TV's settings; so far, we haven't encountered any data on TEXT3 and TEXT4.