I'm trying to document how podcast clients handle namespace extensions to feeds, I've long had the belief that the formal specifications are poorly respected. So far I've started writing a set of tests that I carry out and see just how bad they are.
So far I've tested and publish the results of AntennaPod, Overcast and Apple Podcasts. Apple podcasts on iOS is currently has the best results, but even with all of Apple resources it's not perfect.
I'm planning on expanding the project into documentation for podcasters to use and identify how they should format the feeds, and understand how the clients are working (or not working).