podcast:transcript

A link to transcripts and/or captions for a podcast episode

The official specification

This tag enables:

closed captions, or subtitles - timed text appearing on-screen alongside the audio
transcripts - a document containing the full text of a podcast episode

These are vital for accessibility: those who are deaf or hard of hearing, or for those temporarily unable to listen to the audio.

They can also be used for indexing podcasts for search engines, allowing users deep-search into a podcast’s content, rather than merely the description or title.

Transcripts or closed captions can also be used to better identify appropriate advertising alongside content, or to ensure brand safety for advertisers who wish to avoid appearing alongside certain subject matter.

Objections

“On-device captioning exists on many operating systems” or “Podcast apps can automatically transcribe audio on demand” : this is fine as a fall-back where captions don’t exist, but automated transcripts are not 100% accurate, and may open up podcasters or app developers to legal challenge. As one example: “Margaret Thatcher beat miners” is historically accurate, but “Margaret Thatcher beat minors” is not; and an allegation of child-beating against a former UK Prime Minister might be sub-optimal.

“We have the technology to auto-transcribe, so we’ll use that” : in order to properly respect creators’ work, your app or service should use a transcript if one is presented to you through the RSS feed, which may be corrected and better quality than an automatic version.

Support

Apple Podcasts

This is the first new podcast namespace feature to be explicitly supported by Apple. Indeed, we’re told that VTT files from publishers are the only way to enable support for multiple named speakers. You can opt-in, through Apple Podcasts Connect, to ingest new transcriptions from your podcast host via RSS. Support for the public will be seen in Spring 2024 with the launch of iOS 14.7. It is visible now on the developer beta of iOS 14.7.

Podnews has detailed information on how Apple Podcasts Transcriptions work.

Podcast hosting companies

This is simple to implement for podcast hosting companies. The file can exist on a third-party website, so this work can be provided by a subcontractor or service that a podcaster may wish to use. Transcripts may be a product differentiator for you, or you may be able to achieve additional revenue by providing this service in a premium tier.

It’s one of the most well-supported tags by large podcast hosts, including Buzzsprout, Captivate, Fireside and RSS.

Tip: like audio, ensure that CORS headers are set and open, so that everyone can use the files.

Podcast apps

For podcast apps, linking to transcripts is a simple webview with accompanying UX.

For captions in playback, libraries already exist to decode and play subtitle files, which are easily associated with media playback controls.

Both the [CC] icon and a subtitle icon are part of Android’s Material Icon set, while a caption icon is available in iOS and macOS’s SF Symbols set.

It’s supported by a number of larger podcast apps including Podcast Addict, one of the more popular podcast apps for Android, along with PodLP for KaiOS devices, and a wide variety of apps for iOS, Android and the web.

Podnews contains full details of support from Apple Podcasts. Apple’s support is opt-in, and uses the VTT (or an SRT fallback) file, which it then matches to the audio.

Examples in the wild

The Podcasting 2.0 show (RSS) includes closed captions, using an SRT file.

Listen on the web using PodFriend - click “play this episode” to see the closed captions automatically appearing as you listen.

Apple Podcasts support looks like this. This video shows Apple’s own automatic transcripts, but will look identical for publisher-supplies VTT files.