how do closed captions work on VHS tapes if I turn them on through my TV settings?
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Closed captioning on VHS is written into some “blank” areas of the video that are present, but not shown on the screen. There’s a long technical explanation, but its pretty uninteresting, and is just part of how the VHS format works that these blank areas exist and theres a lot of things available to be put in these “blank” spots, such as copy protection, and more. When you turn on closed captions, it knows to now show those areas as closed captioning, and thats all.
This guys channel has interesting videos. This is a link to one that explains closed captioning.
Old TV stations used to transfer each image line by line. So the signal would transmit the first line, then the second line and so on. For reasons that became obsolete later, they needed to make a pause between sending the last line of an image with the first line of the next.
This is called the Vertical Blanking Interval.
Your TV would automatically not display anything in this time.
People quickly figured out, that in that time, you could put whatever you wanted, and they could make a TV use it for things other than showing images.
So in the 90s the government made TV stations transmit closed caption data in line 21 of that VBI, and then they made TV makers have their TVs read that data.
VCR just recorded all those extra lines and played it back to the TV, who would read it like it was just another TV station signal.
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