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How does closed captioning work?

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Wiki User
2015-09-24 22:04:24

Closed captioning is a digital signal included with the main TV

signal that a closed captioning decoder decodes, turning that into

letters and displaying it on your screen. Many TV's have closed

captioning decoders built in.

If you're ever watching TV and at the top you see some little

white lines, some short, some longer, that's actually the closed

captioning signal you're seeing on your screen. Most TV's don't

display it because of what they call, `overscan` but on some older

TV's when the TV ages, it'll become apparent.

If I remember correctly, closed captioning is included on line

18 of the video signal.

Closed captioning is a text version of a television show that can

be read on screen.

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