Captions

Captions are text representing spoken words, such as dialogue or narration, and other meaningful sounds in the video.

Meeting the Web Accessibility Standard

When a pre-recorded video is captioned, this meets WCAG 2 Success Criterion 1.2.2 Captions (Prerecorded) (Level A).

When live video is captioned, this meets WCAG 2 Success Criterion 1.2.4 Captions (Live) (Level AA).

Note: The Web Accessibility Standard currently requires captioning for live video that delivers high-stakes information or services. Live video that does not present high-stakes information or services is exempt from the requirement to provide captions. For more, see exception 3.4 Live captions — Web Accessibility Standard.

How captions work

Captions are time-indexed and synchronised to appear on the video screen at the same time as the words are spoken.

If more than one person is speaking, the captions should identify who is speaking.

Examples of videos with captions

Closed or open captions?

Captions are either ‘closed’ (can be turned on and off) or ‘open’ (always on).

Generally, it’s best to provide closed captions so that people can choose whether or not to turn them on.

Sometimes, there’s a good reason for providing open captions — for example, a video at a trade show booth where audio is not permitted.

How captions make a video more accessible

Captions provide access to video content for people who:

have a hearing impairment
have an auditory processing disorder
have a learning or intellectual disability
are not fluent in the language spoken in the video and find that reading the captions while listening to the audio improves comprehension
are in a noisy environment where they cannot hear the video properly
are in a public environment, like a library, where they do not want to make any noise.

Captions are also helpful for developing literacy, both in children and adults.

Tips for captions

Timing and placement of captions

Ensure captions:

appear on the screen exactly in time with the audio dialogue
do not obscure important visual content on the screen.

Identifying multiple speakers

If there is more than one speaker, display in capital letters the name of the speaker before their dialogue.

Additional auditory information in captions

In addition to the spoken words in the video, captions should include all sounds or tones of voice that are meaningful in the video. These types of captions should be set in square brackets.

If more than 1 person is speaking, the captions should identify who is speaking.

Examples of meaningful sounds

[laughs], [sighs], [whistles]
[window slams], [sound of explosion], [doorbell rings]
[sarcastically] — used to indicate the tone of voice, if this is necessary to understand the meaning behind the words
[overlapping speech] — used if people are talking over each other
[inaudible] — used when speech is indiscernible or inaudible
[background chatter], [birds singing], [silence] — used when there is a significant break in audio and nothing is spoken for a while

More tips for captions

How to create closed captions

Pre-recorded videos

For a pre-recorded video to have closed captions, it needs to have a caption file.

A caption file is a text file that contains:

the text of the spoken words
descriptions of meaningful sounds — provided in lower case letters and set within square brackets
timecodes for when each line of text should be displayed so that they appear at the same time as the sound occurs in the video.

The most common caption file format is SubRip (.srt).

Use a free or paid-for service to generate a caption file.

Free service

If the video is hosted on YouTube.com, the caption file can be created for free.

Turn on automatic captioning.
Check the autogenerated captions.
Edit the captions to make sure that they accurately describe what is said and include the important sounds.

For more details, see Use automatic captioning — YouTube Help.

There are other free tools available, such as:

If you have your own video hosting service and custom video player, make sure they support captions.

Paid-for service

Caption files can also be created through a paid-for third party service.

These are some examples of services that provide video captioning:

3Play Media — (closed and open captioning)
Able — (closed captioning only)
CaptionSync — (closed and open captioning)
Cielo24 — (closed captioning only)
Rev — (closed and open captioning)
VEED.IO — (closed and open captioning).

Prices and features vary from service to service.

How to create open captions

To include open captions in a video, choose one of the following options.

Create and import a secondary file into the video editing software before burning the captions into the video — this secondary file is known as a sidecar file and it needs to be in the appropriate format for the video editing software.
Use professional video editing software to burn the text onto the video.
If you’re not familiar with the above processes, use a paid-for video captioning service.

Live captioning for live videos

Live captioning is done in real-time by a trained stenographer using a special keyboard.

More information on captions

For more general information on captions, see Captions/Subtitles — W3C.