January 18, 2017 By Ben Kalb

Understanding Captions (and Their Place)

Understanding closed captioning

Almost everyone has used captions at one time or another, whether they are hearing impaired or not. Think about it – how many times have you read captions in a restaurant or at the gym? Closed captions are used everywhere.

After doing my own personal survey, I have realized that most people don’t have a good understanding of the basic types of captions. Sure, everyone is familiar with them at some level, but many people don’t understand the different types and uses of captions, and why captions are set up the way they are.

So if you’ve ever wondered why captions are done a certain way, or if you just want to show off your superior captioning knowledge at your next company picnic, keep on reading.


To set the record straight, subtitles are not captions. However, I’ve included them here because it is important to understand what makes them different from captions.

Closed captions were developed for the deaf and hard-of-hearing audience to be able to read along with the TV program they are watching. The technology allows captions to be “encoded” into the video signal and transmitted over the air (or played from tape) to the viewer’s home. A “decoder” chip installed in the viewer’s TV set (or set-top box) allows the captions to be turned on or off. Usually, the text has white letters on a black background and can be placed in many different areas of the screen. Closed captioning technology has been around for many years and is now required on almost all broadcast TV programs.

Subtitles are a little different. They were developed to allow the viewer to read text translated from a foreign language. They could be presented in a wide array of font and color combinations and almost never have a black background. The text is not encoded into the video signal, so there is no way to turn them on or off using a TV set decoder. The introduction of DVD changed that slightly. Subtitles used in DVD or Blu-ray can be turned on or off from the DVD menu. In addition, DVD and Blu-ray usually offer the viewer the choice of watching subtitles in one of multiple languages.

Captioning is a different thing altogether, and there are two captioning methods widely in use today.

Roll-up Captioning

Just like this term implies, the captions roll up the screen line by line. Usually two or three lines of text are displayed on the screen at a time, either at the top or bottom of the screen. Because this is the most basic form of captions, a simple double chevron is often used to indicate speaker changes (>>) and only minimal sound effect descriptions are included.

This type of captioning is used for all live event broadcasts and some post-production broadcasts that have few speaker changes. Roll-up captions are a very popular style for broadcast because this style is more economical and requires less time to produce and format. The downside to roll-up captions is that they are often harder to follow. As the captions roll by, it may become difficult to comprehend details such as speaker changes and sound effects when they occur in quick succession.

Pop-on Captioning

This is the most descriptive form of captions. The text “pops” on and off the screen in sync with the audio. Each caption usually consists of two or three lines of text and is carefully placed on the screen to avoid covering graphics and faces while also identifying the speaker. Sound effect description is also included in the pop-on style.

Pop-on captions are the easiest to read and comprehend, but the process of creating them is much more detailed, time intensive, and more of a financial burden for small broadcasters.

No matter which method is used, captioning itself proves to be a useful tool, and one viewers will appreciate, whatever their reasons for using the captioning.

**Note: The statements made about closed captions refer to CEA-608 Line 21 captioning. CEA-708 captions that are created for ATSC digital streams have a wide range of additional features that we have not attempted to explore in this article.

Ben Kalb

Ben is a broadcast engineer and creator of StationDrop. With a longevity in the broadcast industry, over 20 years, Ben has experience with everything from 1” tape reels to completely file-based workflows. Recently, Ben has broken into the world of coffee. Ask him about his latest brew.

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