How did the TV know what closed captions to show when VHS tapes were played?
In: Technology
Closed captions are very simple digital data encoded in line 21 of the video. Line 21 is not displayed on normal tvs. However if you have an old VCR and TV you can adjust the vertical hold until the picture rolls and then you can see the caption data appearing as lines and dashes in the black area above the picture as it rolls.
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