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Author Topic: Old teletext is stored on your old VHS tapes  (Read 298 times)

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Offline mr_lou

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Old teletext is stored on your old VHS tapes
« on: 08:26, 27 January 19 »
Did you know, that when you recorded a movie from TV back in the old days, you actually also recorded the teletext?
This is because teletext was broadcasted on an unused bandwidth in the TV signal - and your VHS recorded recorded the whole signal.
This means that there are actually "backups" of teletext here and there without anyone (well most of us) thought about it.  :)
VHS tapes aren't quite hires enough to give good results though. It requires some processing of the data after fetching it form the tape. But S-VHS tapes should be hires enough for you to actually click the teletext button on the remote when playing back the tape today, and then browse the teletext from the day the recording was made.

https://www.alphr.com/life-culture/1002880/the-teletext-salvagers-how-vhs-is-bringing-teletext-back-from-the-dead

Offline tjohnson

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Re: Old teletext is stored on your old VHS tapes
« Reply #1 on: 11:56, 27 January 19 »
That's pretty cool although I threw our all my VHS tapes when we moved house about 9 years ago , along with all my cassette tapes and alot of big box pc games and floppy disks.  I still have 2 players although they are no longer used.  Kind of regret throwing all this stuff out but sometimes one needs to clear clutter out.

Offline Bryce

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Re: Old teletext is stored on your old VHS tapes
« Reply #2 on: 12:10, 27 January 19 »
Yes, even the early DVD recorders recorded it too. The easiest way to extract the info is to play the video via UHF into an old TV with Teletext. However, there were early teletext processors that waited for the correct page to be transmitted, these would take quite a while to browse with a VHS tape, the later versions cached the entire Teletext content, so just playing the tape once would fill the RAM with all pages.

Bryce.

Offline GeoffB17

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Re: Old teletext is stored on your old VHS tapes
« Reply #3 on: 16:28, 27 January 19 »
This is rather fascinating.

I did quite a bit of VHS recording, spread over quite a few years.   Quite a few movies.   I still have ALL the tapes.

For quite a while I was using a VHS machine that included the Teletext facilities, although later I was using a TV that had Teletext as well.  Would this make any difference?   I'd guess not, I understand that the VHS records the specific TV signal, and if I was watching/recording a movie, then the tt is not being decoded but is still there?

I assume that if you're recording BBC, then you may have CEEFAX only, similar re BBC2, ITV or Ch 4.

I used to use tt quite a lot, pre-internet days.   I always found it very useful.   Often, exploring the tt was more interesting than the actual programmes being transmitted!

Would be rather interesting to get at what's on the tapes I have, but I've not got a tt TV now.

Geoff

Offline GeoffB17

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Re: Old teletext is stored on your old VHS tapes
« Reply #4 on: 18:05, 27 January 19 »
Reading up a bit about this on the web, and seems that 'mere' VHS is not good enough.   You need S-VHS.   Seems like you may get something from VHS, but not enough to allow the processing to do a useful job.

But who knows.   Could depend on the length of the prog.

All that days pages were being transmitted all the time, so if you recorded a movie (or one tape I have is nearly 4 hrs of a SuperBowl) then there could be many copies of each page, and a piece of software may be able to construct a good-enough image of most pages from multiple versions of the same page?   One of the articles I read explained something like that?

My recordings are mere VHS.   Even worse, I used LP quite a lot, I'd guess that's near useless in this context.

Which SuperBowl.  Dunno, but the Cincinnatti Bengals were playing, and they didn't get to that many!

Edit:  Just looked this up.  1988 season, so Super Bowl Jan 1989, CB vs SF 49ers.

Geoff
« Last Edit: 18:34, 27 January 19 by GeoffB17 »

Offline mr_lou

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Re: Old teletext is stored on your old VHS tapes
« Reply #5 on: 18:08, 27 January 19 »
Reading up a bit about this on the web, and seems that 'mere' VHS is not good enough.   You need S-VHS.   Seems like you may get something from VHS, but not enough to allow the processing to do a useful job.

Yes, but he also wrote that he then created a sharpener algorithm. That way he could extract data anyway, though it did take a full day to do.

The problem with normal VHS tapes is that they aren't quite "hi-res" enough, so the data becomes "blurry". But just as there are image filters that can sharpen your photo, the same way you can sharpen this signal. And that's what he did.