| Closed captions on television provides written notes at the bottom of the screen with dialogue, lyrics and action descriptions.
Closed captioning involves the insertion, into the blank lines between frames, of information that may be decoded and displayed on the screen as written words corresponding to those being spoken and transmitted via the conventional audio subcarrier.
Closed captioning was developed for the hearing-impaired and is mandated in the United States by the Americans with Disabilities Act of 1990. In the United States and in several other countries closed captioning requires a special decoder, which may be external to, or built into, the television receiver. |