Podtrac measurement is certified by the IAB. Podtrac recommends that podcast publishers follow IAB recommendations for podcast Players. The IAB Podcast Measurement Guidelines version 2.1 contain the following recommendations for podcast Players:
- Do not implement auto-play. This will result in a bad user experience.
- Do not pre-load audio content unless there was a clear action taken by the user to request the content.
- Use ID3v2 tags so that the headers are located at the start of the podcast (not at the end). This allows Players to use the ID3 data ahead of streaming without downloading the full podcast file.
- Limit ID3 tag sizes to 300kb with 800x800 pixel maximum for artwork.
- For a full download, ask for the entire file at one time. For a progressive download, ask for the file in slices (byte range). This way a full download can be distinguished from a progressive download.
- Do not modify the enclosure URL when requesting media, don’t add extra parameters.
- Do not cache podcast episodes on your servers. Always download the latest episode from the enclosure URL for every app user wanting to listen.
- Use the GUID -- as opposed to episode URL, title, publication date, etc. -- to identify new episodes in the RSS feed that should be automatically downloaded to a user’s device. The GUID is designed to be persistent through changes to hosting environment, titles, etc.
- Employ an “automatic download unsubscribe” behavior (e.g. - stop auto downloads after 5 episodes of non-listens).
- Do not automatically download all episodes (e.g. back catalog episodes) by default. This creates unnecessary drain on the publishers’ servers and consumes users’ bandwidth.