[BBC-Micro] Teletext

Phil Blundell philb at gnu.org
Mon Jun 1 23:15:37 BST 2009


I think the chances of recovering usable teletext data from a
1984-vintage videotape are pretty small.  For one thing, teletext is
transmitted in the vertical blanking interval, which isn't an area of
the picture that VCRs make any particular effort to capture (and,
consequently, is where they do their head switching).  For another
thing, most older VCRs had fairly lousy video bandwidth and, although
the datarate of teletext wasn't exactly massive, I suspect it was
probably still too high for the bits to survive the transfer to and from
the tape without getting hopelessly smeared.

Modern VCRs are a little bit better but recording the VBI is still not a
high priority and I wouldn't be surprised if it fails.  DVD recorders,
as far as I know, only record the active picture area so you wouldn't
get any VBI data at all.

If you want to archive Teletext for posterity then your best option is
probably to use a PC with a capture card and just stream the VBI bits to
disk.  You could even have multiple capture cards and record all the
channels in parallel if you wanted.

p.

On Mon, 2009-06-01 at 22:42 +0100, Ian Wolstenholme wrote:
> Is there a way of recording the teletext signal onto videotape or
> DVD so it can be decoded with a Teletext adapter at a later date?
> 
> I'm hoping that I will be able to save as many pages from Teletext as
> possible before the signal is switched off.   There are only 5 months left
> round here, so it would be handy if I could make some recordings and 
> download the teletext pages at my leisure at a later stage.
> 
> On a related point, can teletext information be recovered from existing
> off-air recordings?  I've a few videotapes from the late 1980s and early
> 1990s (and onwards) and it would be nice to be able to download Teletext
> pages from this era, as all this information has probably been lost forever.
> 
> If I can find that old tape of the 1984 Olympics, it might have some
> Telesoftware on it...........
> 
> Best wishes,
> 
> 
> 
> Ian
> 
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