Two ways to show the same words
Captions can reach the screen in two broad ways. With closed captions, the text is kept separate from the picture, and the viewer decides whether to show it. With open captions, the text is part of the image itself, so everyone who watches sees it and nobody can turn it off.
The words may be identical. What differs is who is in control and what happens to the text on the way to the viewer.
Closed captions
Closed captions travel as a data layer or a separate file alongside the video. The player or device reads that layer and draws the text when the viewer has switched it on.
Advantages typically include:
- Choice. People who want captions can have them, and people who do not are not forced to see them.
- Customization. Many players let viewers change the size, color and background of the text, which can help people with low vision or reading differences.
- Multiple languages. One video can offer several text tracks and let the viewer pick.
- Editing. If an error is found, the text file can be corrected without re-encoding the video.
Drawbacks are mostly about dependence on the player and device:
- A player may not support captions at all, or may display them poorly.
- Some platforms and screens strip or ignore the data.
- Viewers have to know the option exists and find the control.
Open captions
Open captions are rendered into the video image before it is distributed. Whatever the video is played on, the text appears exactly as designed. Another common name for this approach is burned-in subtitles, which are discussed further in their own trade-offs article.
Advantages include:
- Reliability. The text shows on any screen that shows the video, including ones with no caption controls.
- Consistent design. The producer decides the look and position, which can be coordinated with the picture.
- Fit for silent screens. On public screens that play without sound, permanent text may be the only practical way to deliver speech.
Drawbacks include:
- No viewer control. People who find the text distracting cannot hide it, and people who need larger text cannot enlarge it.
- One language per version. A new language usually means another rendered copy of the video.
- Harder to fix. Correcting a mistake means producing the video again.
- Quality loss risk. Text rendered into video can look soft after compression, particularly at low resolution.
Why the options have multiplied
Early captioning in broadcast television used closed captions that viewers switched on with a decoder or a setting. As video moved online and onto many kinds of devices, producers found that support varied widely, and some chose to make captions part of the picture to be sure they appeared.
Habits changed too. Sound-off viewing is common, for instance in quiet or noisy places, and people expect text to be present. Feeds of social video that play clips silently by default made permanent text a common design choice. At the same time, players improved their support for separate text tracks, so both approaches now have a place.
Choosing between them
There is no universal answer. These questions can guide the decision:
- Where will the video be played? A controlled platform with good caption support favors closed captions. A mixed or unknown environment, or a screen with no controls, may favor open ones.
- Does the audience include people who need to adjust the text? If so, closed captions give them tools open captions cannot.
- How many languages are needed? More languages usually point toward separate tracks.
- How likely are corrections? Content that changes often is easier to maintain with separate files.
Some producers offer both: a clean version with closed captions and a version with permanent text for social posts or public displays. This takes extra effort but can fit different contexts.
Making open captions work well
If open captions are the choice, a few practices help.
- Keep the text clear of faces, important graphics and other on-screen text.
- Use a high-contrast style with a background or outline so words stay readable on changing scenes.
- Keep lines short and give them enough time on screen to read.
- Check the finished video on a phone as well as a large display.
The same quality principles apply regardless of format: accurate wording, good timing and a readable look. Open captions give up the viewer’s ability to fix a poor design, so extra care is needed before export.
Rules and expectations
Whether a particular organization must offer closed captions, open captions or either depends on local rules and on the type of content. Requirements vary by place and change over time, so the relevant authority or a qualified professional should be consulted for specifics.