So, I recently noticed -allright, I had noticed a long time ago but wasnt curious enough to ask - that some TV transmissions have what I can only distinguish as some data blocks on top of them. they are mostly visible when the horizontal sync is lost and the picture scrolls. So my question is... can anyone tell me what they are, if they are a standard and you know... give me an introduction to them? Thanks.
Videotext? 🙂
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Jo22 wrote on 2022-03-31, 09:33:Videotext? 🙂
I also thought that it could be CC but I am unsure.
PC Hoarder Patrol wrote on 2022-03-31, 10:56:
Hmmm... I dont know about that. I know that the VBlanking has been since forever in NTSC/PAL but there is something in there, some data... I want to know more. Not every program has it but interestingly enough, some DVD's DO have it as part of the analog signal.
Might be subtitles.
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Teletext
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weedeewee wrote on 2022-03-31, 20:04:Teletext
Ok. It turns out it is Closed Captioning. I didnt know that. I thought it was some other sort of signal like RDS in radios and things of that sort. Im guessing that is also an option too.
Donovan V. wrote on 2022-03-31, 16:45:PC Hoarder Patrol wrote on 2022-03-31, 10:56:Hmmm... I dont know about that. I know that the VBlanking has been since forever in NTSC/PAL but there is something in there, some data... I want to know more. Not every program has it but interestingly enough, some DVD's DO have it as part of the analog signal.
https://en.wikipedia.org/wiki/Teletext#Data_transmission
teletext was coded inside Vertical_blanking_interval, as were captions. There was even a group reconstructing old Teletext from TV programs recorded on VHS https://www.alphr.com/life-culture/1002880/th … -from-the-dead/
Donovan V. wrote on 2022-04-01, 04:36:weedeewee wrote on 2022-03-31, 20:04:Teletext
Ok. It turns out it is Closed Captioning. I didnt know that. I thought it was some other sort of signal like RDS in radios and things of that sort. Im guessing that is also an option too.
In ATSC there's the program guide data, but that should come through on analog.
Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.
Allright. Thank you all who gave me an Idea of what was in there. It turns out... SMPTE signals can be embbeded there. There is Closed Captioning and the ones I think I was confused by were the boxes for Macrovision. Of course, there is Teletext but i've never seen one in the wild because, I live in a region were NTSC reigns supreme and we never had it. (I never had Closed Captioning until recently, but I am in this case, speaking about my childhood and seeing those blocks on a broadcast, not knowing what they were)
I am now curious, if there is any application to embed Closed Captions on video that doesnt cost an arm, a leg and your firstborn... hmmm... Any pointers would be greatly appreciated.
BitWrangler wrote on 2022-04-01, 14:47:Donovan V. wrote on 2022-04-01, 04:36:weedeewee wrote on 2022-03-31, 20:04:Teletext
Ok. It turns out it is Closed Captioning. I didnt know that. I thought it was some other sort of signal like RDS in radios and things of that sort. Im guessing that is also an option too.
In ATSC there's the program guide data, but that should come through on analog.
That sounds interesting. Honestly I am not versed enough on ATSC (im not much of a tv guy nowadays) to properly understand it. As far as I am aware is an Mpeg stream over an analog carrier, much like analog video BUT the signal is a digital compressed rather than analog modulation right?
