How does the subtitle text function on TV's work?

Question

For example if I turn my mute button on with my television and leave it on for a while it will automatically start showing the conversation in text for deaf viewers. However is this a function of the TV or does like the specific show/station have to input/embed that into their shows?

Answer 1

Subtitle and the TV display are two different thing.

Every subtitle have some sort of hidden system message that consists of condition to appear, the position of subtitle in the screen, and at what time the subtitle appear.

So, the subtitle appear at specific time it was programmed and sync it with the performance on TV.

Subtitle, it's kinda like a second program running in your TV other than your shows.

Answer 2

The program producer has to have the closed captions added to the show.  Many times, this is done by a Court Reporter, especially for live shows like news.

The older EIA-608 closed captions (analog TV) were placed on line 21 of the picture, witch is above the picture off screen.

The newer EIA-708 closed captions (digital TV) are data sent along with the program.

I hope this helps. Please return and select a Best Answer from all of those submitted.