What’s the Acceptable Format for Media Captions and Transcripts? 

August 9, 2022

Captions and transcripts are essential accessibility features. They’re also good for business: studies show that people of all abilities are more likely to watch videos — and remember brands — when they have access to text alternatives.

In one survey from Verizon Media, 80% of respondents said that they were more likely to watch a full video when captions are available. Transcripts improve search engine optimization (SEO), ensuring that your multimedia reaches the largest possible audience. When NPR’s This American Life added transcripts for its podcasts, 1.14 million unique visitors viewed at least one transcript.

Does WCAG require captions and transcripts?

The Web Content Accessibility Guidelines (WCAG) requires captions for all prerecorded multimedia. The guidelines also require transcripts for all pre-recorded audio-only and video-only content. 

When content includes both video and audio content, transcripts are only required at WCAG’s Level AAA (read more about WCAG conformance levels). However, it’s generally a good idea to provide transcripts for all media to provide your audience with more options for enjoying your content. 

By thinking about captions and transcripts when creating your videos, you can fulfill this requirement (and expand your reach). With that said, you’ll need to make sure that your text alternatives provide useful information. 

Related: Do I Need to Write Podcast Transcripts for Accessibility?

Acceptable Formats and Accessibility Requirements for Captions

Wherever possible, use closed captions. Closed captions consist of a separate file with text content, which allows users to enable or disable the captions according to their preferences. 

.SRT is an example of a closed caption format. For most content creators, .SRT is the most appropriate choice, as it is widely supported by Facebook, YouTube, Windows Media Player, and other media players and online video platforms. Others caption formats include: 

  • Web Video Text Tracks (WebVTT), a user-friendly format for HTML5 video players
  • Scenarist Closed Captions (SCC), commonly used for broadcasts and DVDs
  • Distribution Format Exchange Profile (DFXP), developed by the World Wide Web Consortium (W3C) and commonly used for Flash videos

Generally, the quality of your captions is more important than their format. The SubRip (.SRT) format is especially popular, but other formats are acceptable, provided that those formats meet the following requirements: 

  • The captions support the presentation of text through a screen reader (software that converts text to audio or braille). 
  • The captions are appropriately synced with the video presentation. 
  • The captions do not obscure important visual elements and maintain an appropriate color contrast ratio. 
  • The captions describe all important sounds, including meaningful music cues and sound effects.
  • When a video contains multiple speakers, the captions identify each speaker.

Can I use pre-rendered captions on my videos?

Prerendered (also known as “open" or “burned-in") captions are less than ideal, since they’re not accessible for screen readers and users cannot use translation tools, change the font size, or customize the text in other ways. However, pre-rendered captions may be used on certain platforms that do not support alternatives. 

Related: Avoid These 4 Mistakes When Writing Video Captions for Accessibility

Acceptable Formats and Accessibility Requirements for Transcripts

Transcripts provide a complete text alternative to multimedia, which can be especially useful for people with vision or hearing disabilities. Basic transcripts include descriptions of all speech and audio cues from the multimedia presentation. Descriptive transcripts may include additional details such as descriptions of visual content. 

Some quick tips to keep in mind: 

  • The best format for transcripts is HTML. You can also provide downloadable transcripts in.txt., .doc., or other widely supported formats, but remember that many users prefer HTML — and publishing HTML transcripts can benefit SEO. 
  • For longer transcripts, use headings to organize the content. Consider adding hyperlinks to make the transcript more useful. 
  • Do not include timestamps, unless the timestamps provide useful information. 
  • Writing transcripts can be a time-consuming process. Get into the habit of drafting your transcripts when planning your videos. 
  • Make sure users can find your transcripts. Place a prominent link on the same page as your video or audio content. 
  • Consider adding links to your transcripts when promoting content on social media.

Finally, make sure you review your captions and transcripts before publication. Errors can be frustrating for users — and embarrassing for your business. 

For more tips, read our Ultimate Guide to Web Accessibility or talk to our subject matter experts.

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