Some podcast publishers choose to provide additional chapter information when they publish their podcast episodes, breaking down a single episode into multiple segments - each of which may have a title, link, image, etc.
Right now, there are four mechanisms that podcasters can use to do this:
- Embed chapter information directly inside the MP3 audio file using standard ID3 tags, with tools such as Forecast.
- Embed chapter information directly inside the AAC/M4A audio file using MPEG-4 Chapter Lists.
- Include chapter information inside the RSS feed at the episode level using the Podlove Simple Chapters spec, first published in 2012.
- Create a separate json file with the chapter information, and reference it from the RSS feed at the episode level using the newer Podcast Namespace Chapters spec.
Apple recently published Using chapters on Apple Podcasts to highlight this little-known feature of podcasting.
Since we already analyze every single new podcast episode published to produce our podcast host, tracker, and CDN rankings, we are in a good position to see how often podcast chapters are used in the wild, and which mechanisms are most prevalent.
Podcast Chapters frequency, by mechanism
as a percentage of all new episodes published in the given month
|Month||Any Chapters||ID3 Chapters||Namespace Chapters||Podlove Chapters||M4A Chapters|
About 1 in every 82 new podcast episodes provide chapter information.
In the last month, ID3 tags are the most popular mechanism.
- about 4.5x as prevalent as the Podcast Namespace chapters
- about 16x as prevalent as Podlove chapters
- and about 38x as prevalent as AAC/M4A chapters
Analysis by John Spurlock
Thanks to the Podcast Index for crawling every podcast, and giving us a signal of when to check for new episodes.
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