Ever Wonder What’s Behind Closed Captioning?

Feb 3, 2015

Credit Daniel Olnes / Flickr

When working out at the gym or sitting at a noisy bar, you’ve probably watched the scrolling text on the nearby TV screen to find out what’s being said. Closed captions have been available for TV since the early days of Julia Child.

While the service caters to people with impaired hearing, it can be useful for anyone in any number of situations. Online, captions are mandated for some videos and you can even add captions when posting your own Facebook videos.

But how does closed captioning work? Who or what brings the words to our screens? VITAC, a Pittsburgh-based company, is responsible for at least half of the captions on the air nationwide and a growing amount of our on-demand streaming. VITAC Chief Operations Officer Chuck Karlovits gives us a look inside the world of closed captioning.

Karlovits explains that captioning relies on two things: on the one hand, a clear audio source, and on the other hand, the work of either steno captioners or voice recognition technology.

The majority of captioning on TV and online is done by steno captioners, Karlovits says. These steno captioners do not use traditional keyboards but rather special entry devices that allow the captioners to register various syllabic sounds. While VITAC has a facility at Canonsburg, most steno captioners work from home, Karlovits explains.

Voice recognition software is also used, but its accuracy rate is generally much lower -- about 70% -- than when transcribed by a professional steno captioner.

Watch this episode of Pittsburgh Dad with captions produced by voice recognition software. Enable the captions by clicking the small screen-shaped "CC" icon at the bottom right of the video:

Compare the above video to this one, whose captions were provided by VITAC:

Another option is prerecorded captioning, in which video material is provided to the captioners in advance, who are able to play and replay material for excellent accuracy.

Captioning comes with lots of different challenges, Karlovits says. For instance, VITAC provided the captions for the Super Bowl on Sunday, and for live events of this kind, effective captioning requires research in advance and other preparation in order to better caption events as they unfold in real time.

Unusual speech and strong accents also require special consideration, Karlovits explains.