from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The display of text on a television or video screen, usually a transcription of the audio portion of a program as it occurs (either verbatim or in edited form), used by the hearing-impaired and language learners. Closed captions are encoded invisibly, and displayed by a decoder.
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Sometimes described as an 1125-line standard instead of 1080, an HDTV signal includes 45 “hidden” lines, used for closed captioning and other useful data.