Teletext time travel

tbs.pm/8285

Transdiffusioner Jason Robertson has a complicated but fun project underway – recovering old teletext data from VHS cassettes.

Previously, it was possible – difficult but possible – to recover teletext from SVHS recordings, but they’re as rare as hen’s teeth as the format never really caught on. The data was captured by ordinary VHS but was never clear enough to get anything but a very few correct characters in amongst a massive amount of nonsense.

Technology is changing that. The continuing boom in processor power means it’s now possible to feed 15 minutes of smudged VHS teletext data into a computer and have it relentlessly compare the pages as they flick by at the top of the picture, choosing to hold characters that are the same on multiple viewing (as they’re likely to be right) and keep trying for clearer information for characters that frequently change (as they’re likely to be wrong).

All of this takes phenomenal amounts of processing power and therefore time. The longer you run the data comparison, the better the results – but we’re still talking days rather than hours in many cases. Moore’s law should see this fall in future, but until then Jason is ploughing on – and making the results available to us all online.

The pages are a snapshot of life in the 1980s – British Rail train times, Mrs Thatcher’s opinions, new pound coins and Gus Honeybun – and therefore fascinating for historians of modern life as well as the huge numbers of us who love – and miss – having teletext at our fingertips.

Unique Code & Data [Jason Robertson]