2009-12-15 · in Tech Notes · 348 words

C4 Teletext page 100.04 ITV Teletext page 106.08 C4 Teletext page 301.07 ITV Teletext page 117.36

Teletext Ltd., who took over in 1993 from Oracle as the commercial teletext provider on ITV and Channel 4 in the UK, announced in mid-2009 that they were planning to stop providing their "news and information" services as of December 15th — for which Ofcom later revoked their broadcast license. I thought it'd be interesting to grab a complete copy of ITV and C4 teletext before this happened.

This turned out to be pretty straightforward: the ZVBI library comes with sample programs to capture the VBI stream from a TV card, and to decode it into page text or images later. I set up a spare PC with a cx88 TV card, tuned it to the analogue channel I was after on the Dover transmitter with v4lctl, and ran:

./capture -v -l -p -d /dev/vbi1 -o ~/ch4-20091214.dump

On the evening of the 14th, I left capture running for about an hour on both ITV and C4, and did a shorter grab of BBC1. I repeated this on the morning of the 15th and the evening of the 15th; the services actually disappeared at some point in the middle of the day on the 15th.

Each page on a UK teletext service can have a carousel of subpages which the broadcast service cycles slowly through, so I wanted to ensure that I'd got all of these — and there were some unusually long carousels that night, as most of the sections were running farewell articles of some kind with readers' letters and favourite sets of graphics. The Turner the Worm comic on ITV had 50 subpages, each being shown for 30 seconds.

To decode each stream dump into images, I ran:

./export -v -o pages/page png <~/ch4-20091214.dump

ITV Teletext page 158.05 ITV Teletext page 105.02 C4 Teletext page 341.01 C4 Teletext page 490

Browsing through the output, it's striking just how much content there was on Teletext — before the shutdown there were about 4000 subpages on each service. However, most of this is commercial (e.g. travel and betting services); after the shutdown, around 3200 subpages remained.

Anyway, should I need to recreate Teletext circa 2009 at some point in the future, I'm now able to do so.