The Teletext Salvagers: How VHS is bringing teletext back from the dead

Brilliantly, Alistair Buxton has also created software that will turn a Raspberry Pi into a teletext broadcaster. Simply install the software with a few taps on the command line and plug the Pi into your TV using the old-fashioned RCA socket rather than HDMI. Then it’s just a case of hitting the teletext button on your TV remote to see a fully working teletext system, just as you remember it. This isn’t a simulation or a recreation using the Raspberry Pi’s graphics processor – this is teletext inserted into the TV signal in exactly the same way that it was back in the day.

This is fun for us laypeople, as Alistair has included vintage archive of teletext pages to browse with the software, but it also serves a smarter purpose for the archaeologists. Alistair has created a series of text pages with a very specific pattern, and used the Pi to record this to VHS.

Reading this data from a VHS back into his capturing system has enabled him to create a lookup table. This is essentially a teletext cheat sheet – he now has data on what many different combinations of teletext bytes might look like, rather than having to crunch and compare each byte manually with the original image algorithm, which makes the process of decoding much faster. At the moment, the new system is less accurate than the slow method, but brilliantly, it makes it possible to capture the teletext signal in “near real time”. This means no more waiting for a day to process a single set of pages.

Club 140

Browsing the data that Jason has captured and processed is a blast from the past. If you follow him on Twitter, you’ll see that he’s recently been bringing back from the dead pages of the much-loved Channel 4 video-game section, Digitiser – and has been able to share them with its writer, Paul “Mr Biffo” Rose, who has described Jason as a “legend” for his work.

At the moment, Jason and Alistair are pretty much the only real teletext archaeologists – although the wider teletext “scene” appears to encompass a few hundred people. Jason tells me he has ideas about making a proper archive, but this appears to be a way off yet.

At the moment, the best place to find what has been captured is on Jason’s blog.

Do you see?

Google’s Vint Cerf has warned that we risk a “forgotten century” as humans take their first footsteps into the digital world. He wasn’t talking about teletext, but something much bigger: the internet, of which he is credited as one of the founding fathers.

As fewer and fewer hard records are made of the vast amounts of information on the internet, there is a very real risk that historians of the future won’t have access to material that will help them understand how we lived and why we did the things that we did.

And the problems of archiving the web are much like the ones facing teletext, but on an even grander scale. Just as teletext is locked away on old VHS tapes, much of our formative digital data is stored on formats we no longer use, such as floppy discs. And even if we could access the data, there are real worries about “bit rot” – as file formats change, and old applications give way to new, will we always be able to interpret the 0s and 1s? Sure, JPEGs might be ubiquitous today, but with the march of technology it is surely inevitable that they will be replaced. The billions of photos we have as a record of our lives today could in future become even more inaccessible than the noisy analogue TV signal on an old VHS cassette.

Ultimately, perhaps the work of Jason, Alistair and the other teletext archaeologists is not only valuable in its own terms – as they’re capturing historical data that would otherwise be lost – but could also serve as a warning: we need to be better at looking after our historical data, and we need to change before it is too late.

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