Hidden TV Messages

Q: I have a television set that displays the text of what people say. (Author's note: Almost all sets do.) How does it work? Is it automatic, generated by a computer with voice recognition capability? Is it typed by someone who hears the words? Or is it prepared based on a script? Often the text lags the spoken words by several seconds and contains hilarious mistakes.
Nancy, Albuquerque, New Mexico

A: A closed-caption TV set has a device that decodes and displays the messages. The captions are called "closed" because they are invisible unless you command the set to reveal them. Written in English, Spanish, French, or German, they aid kids learning to read, immigrants learning a language, or the hearing impaired.

It works like this: TV producers place captions in a video signal. The captions are hidden because they go between video frames, in the non-displayed part of the signal.

Captions can be funny and some are better than others. The reason for the disparity lies in the different ways producers generate captions: some easy to do without error and others difficult.

The easiest are done in a studio after the fact: post production. The captioner creates the text on a computer, synchronizes it to the video dialogue, and inserts it into the videotape. He reviews his work to eliminate slip-ups. Television game shows and movies use this procedure.

Live shows are more difficult. Your how-is-it-done guesses are on target for live captioning. The captioner works as the event occurs either from a script or by typing as he listens. News and sportscasts are examples of live events.

(Answered April 1999; updated Oct. 23, 2007)

The script captioner only displays in real time. Before the show, the captioner loads the script into a computer. As the show goes on, he presses the "next caption" button at the right moment in the dialogue or when he sees the next prompt. The captions appear a line at a time. If the speaker deviates from his script, the captions are wrong.

The typist captioner does everything in real time. He listens to the live broadcast and types shorthand at 250 words per minute or higher. Computer software translates and the captions appear a word at a time. Most stenocaptioners started as court reporters and are good. But nobody's perfect.

Further Surfing:

Gary and Kathy Robson: Closed caption FAQ
http://www.robson.org/kathy/cc.html

To see closed captions on your TV: Use your remote control for TVs made since 1990. Otherwise buy an external decoder (about $100).