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In my experience with a few big broadcasters like Paramount (previously Viacom) and Discovery, for broadcast in Europe/UK the signal they generate often has a m

by kvm000 4y ago

In my experience with a few big broadcasters like Paramount (previously Viacom) and Discovery, for broadcast in Europe/UK the signal they generate often has a mix of Teletext and/or DVB inserted based on the channel since those signals are distributed to a LOT of partners like local satellite and cable companies who can decide which parts of the signal to map into their system. In that context, “teletext” just works the same as the North American 608 captions and has nothing to do with the older full-screen data stuff. There are no restrictions around authority for “teletext equipment” - for those channels they actually use systems fully based in AWS with the playout engine running on an EC2 instance so all software-only to generate the single MPEG transport stream with video/graphics + audio + captions + subtitles. It’s also common to send a DVB subtitle multiplex that has a number of languages (up to 20+) embedded in the same signal.

zinekeller 4y ago
To be fair, I'm talking about the old PAL-based teletext and not about DVB teletext. Also, computers are now everywhere so the 888 page can be inserted with minimal effort unlike back then that it requires coordination with different teams.
- kvm000 4y ago
  I was talking about the older PAL-based teletext as well - but you're right, I understand it was different in terms of equipment originally with the full-screen data feeds. Separate from DVB, the old PAL OP42/47 teletext payload gets inserted into the MPEG-TS using SMPTE 2038[1] then when decoded, it would go into regular ancillary data of the uncompressed stream per ITU-R BT.1120-7[2]. The broadcast industry really loves standards[3]. [1] https://ieeexplore.ieee.org/document/7290549 https://ieeexplore.ieee.org/document/7290549 [2] https://www.freetv.com.au/wp-content/uploads/2019/08/OP-42-Closed-Captioning-Issue-5-May-2018.pdf https://www.freetv.com.au/wp-content/uploads/2019/08/OP-42-C... [3] https://xkcd.com/927 https://xkcd.com/927
fredoralive 4y ago
I was under the impression the "teletext" style ones still used teletext encoding, not EIA-608? It's basically just a data steam containing a single page of teletext rather than a whole magazine? AFAIK Sky Digital uses this approach (at least for SD), with a more modern looking decoder, and it certainly has colour support at least[1]. [1] Although DVB can contain a full teletext stream that can be reinserted into the SD analogue VBI by the receiver. Sky boxes supported that so on some channels you could just go to ye olde page 888, although I haven't a clue if any channels still do that (I don't have an old SD Sky setup around to look).
- kvm000 4y ago
  That's correct - 608/708 is North America only, and UK/Europe could use OP42/47 teletext for simple captions (not whole magazine), and/or DVB (mostly language translation).

by kvm000 4y ago

zinekeller 4y ago

To be fair, I'm talking about the old PAL-based teletext and not about DVB teletext. Also, computers are now everywhere so the 888 page can be inserted with minimal effort unlike back then that it requires coordination with different teams.

kvm000 4y ago
I was talking about the older PAL-based teletext as well - but you're right, I understand it was different in terms of equipment originally with the full-screen data feeds. Separate from DVB, the old PAL OP42/47 teletext payload gets inserted into the MPEG-TS using SMPTE 2038[1] then when decoded, it would go into regular ancillary data of the uncompressed stream per ITU-R BT.1120-7[2]. The broadcast industry really loves standards[3]. [1] https://ieeexplore.ieee.org/document/7290549 https://ieeexplore.ieee.org/document/7290549 [2] https://www.freetv.com.au/wp-content/uploads/2019/08/OP-42-Closed-Captioning-Issue-5-May-2018.pdf https://www.freetv.com.au/wp-content/uploads/2019/08/OP-42-C... [3] https://xkcd.com/927 https://xkcd.com/927

fredoralive 4y ago

I was under the impression the "teletext" style ones still used teletext encoding, not EIA-608? It's basically just a data steam containing a single page of teletext rather than a whole magazine? AFAIK Sky Digital uses this approach (at least for SD), with a more modern looking decoder, and it certainly has colour support at least[1]. [1] Although DVB can contain a full teletext stream that can be reinserted into the SD analogue VBI by the receiver. Sky boxes supported that so on some channels you could just go to ye olde page 888, although I haven't a clue if any channels still do that (I don't have an old SD Sky setup around to look).

kvm000 4y ago
That's correct - 608/708 is North America only, and UK/Europe could use OP42/47 teletext for simple captions (not whole magazine), and/or DVB (mostly language translation).