There’s a hook for these persistent identifiers in XSPF — the identifier element. That’s not necessarily a playable version of the content, just a consistent way to identify the content across any number of locator URLs. The wikipedia “Purple Haze” page is a completely valid XSPF identifier, even though it doesn’t return a media file.

This is valuable when you need a level of abstraction beyond a direct locator for a file. For example, a content resolver might try to map the wikipedia page title to the id3 title tag of free range audio files.