NOTE: This article will be focused on best practices for writing captions (either closed captions or open captions) rather than subtitles. To learn more about the difference between captions and subtitles, check out this article! Closed vs. Open Captions vs. Subtitles
The need for captions is outlined under Success Criterion 1.2.2 of the Web Content Accessibility Guidelines (WCAG): “Captions are provided for all pre-recorded audio content in synchronized media, except when the media is a media alternative for text and is clearly labeled as such.”
WCAG does not, however, specify exact guidelines for how to format captions. As such, when captioning a video, there are no definitive “rules,” but there are some best practices to keep in mind!
Length and Timing of Captions:
Captions should be kept to about 42 characters per line and with a maximum of 2 lines per subtitle cell. If a subtitle cell has two lines, the entire cell should not exceed 84 characters.
42 characters is not a hard and fast limit, but it's a good rule of thumb to keep in mind, as shown in these examples:
This caption is 38 characters long:
This caption is 58 characters long:
See how much easier it is to read the entire first caption just by looking at the center of the screen without having to scan across the entire line with your eyes? That's the goal!
Each caption should be displayed for between 1-8 seconds, depending on the length of text. This breaks down to a presentation rate of 15-20 characters displayed per second or 120-130 words per minute.
Line Breaks:
When splitting a subtitle up into two lines, try to keep the idea intact and the lines of equal length. Additionally, both line and caption breaks should follow the natural rhythm of speech without breaking up complete clauses and names, separating articles from words.
Identifying Speakers:
When identifying speakers in an interview, use all CAPS followed by a colon. The first time someone speaks, use their full name. Subsequent times, use their first name only unless there are two speakers with the same first name.
Example:
JOHN DOE: We love captions!
JANE SMITH: And so do millions of other people!
JOHN: Hooray for accessibility!
When identifying speakers in other types of video content, use whatever name the character is best known by and stay consistent throughout.
Use parentheses to indicate when someone is speaking off-screen.
Example: (JOHN): Wait for me!
Describing Meaningful Sounds:
Captions, as opposed to subtitles, assume that the viewer is unable to hear the audio. As a result, it’s important to include non-verbal sounds so that the viewer can understand the entire context of what’s happening. These are often written in brackets to differentiate them from dialogue.
Examples:
[Laughter]
[Gasp]
[Phone rings]
[Jazz music]
If there is music playing without lyrics, try your best to describe the overall feeling of the music. Is it hopeful and upbeat? Suspenseful? The underscoring is used to provoke certain emotions in the viewer. Just because someone can’t hear, doesn’t mean they should miss out on that element!
If music is playing with lyrics, include a music note (♪) on either end of the caption line to denote that the text is being sung.
Example: ♪ Twinkle twinkle little star ♪
♪ how I wonder what you are ♪
Captioning Interviews:
When captioning an interview or unscripted conversation, the goal is to maintain accuracy and relay the overall meaning and intention. It’s okay to exclude things like “um,” “ah,” and other sounds not important to the overall context if it helps make the captions clearer to read.
If at any point the speech is unclear, it should be marked as [inaudible].
Overarching Elements of Quality Captioning:
All of the above best practices fit under the overarching categories described in the DCMP Captioning Key’s elements of quality captions.
While there are no true “rules” for captioning, captions should, above all, always be:
Accurate
Errorless captions are the goal for each production.
Consistent
Uniformity in style and presentation of all captioning features is crucial for viewer understanding.
Clear
A complete textual representation of the audio, including speaker identification and non-speech information, provides clarity.
Readable
Captions are displayed with enough time to be read completely, are in synchronization with the audio, and are not obscured by (nor do they obscure) the visual content.
Equal
Equal access requires that the meaning and intention of the material is completely preserved.
As a reminder, the goal of captions is to ensure that all viewers can have the same experience while watching a video, whether or not they can hear the audio. These guidelines can be adjusted as needed to best suit each specific video’s purpose. Happy captioning!
For more information on how to add captions to a video, automatic subtitling, and more, follow this link: Add Subtitles to Video