Hacker News new | ask | show | jobs
by Symbiote 871 days ago
"Teletext" in this context is a signalling protocol for transmitting text content over PAL TV, for decoding by an appropriate receiver.

The BBC's service was branded "Ceefax", ITV and Channel 4 branded theirs "Teletext".

The current 'red button' service is a completely different protocol running on DVB (Digital Video Broadcast, i.e. digital TV). Text packets are added to the MPEG-2 stream.

3 comments

FWIW you can still get Teletext over MPEG TS (DVB or IPTV), it's just already de-modulated, but even error correction bits are still there (and are useless).

In France most IPTV operators still use teletext for live subtitling because it eats much less bandwidth than dvbsub

The ITV/C4 service was originally Oracle; this was later replaced by “Teletext Ltd”.

https://en.m.wikipedia.org/wiki/ORACLE_(teletext)

Ah, my apologies then. My confusion was that I didn't think there was a difference between the current mechanism and the old one.