This is a probably complicated but big feature request for me. I don't have a ready proposal, but just want to throw it out in the open.
ARs with recordings should be able to have a sequence of timespans for the recording!
This opens up for lots of good stuff. For a medley you could state where in the recording a particular song is played. For an performance you could state which part of the track that performance is heard on. You could state
A big part of what makes Musicbrainz exciting to me is actually not anything that is seen today, but how I imagine it will be when we have even more data and when that data is used and presented in even more ways. In particular I'd want music players that use Musicbrainz a lot more, and this is exactly the type of thing I'd want them to use. A music player should be able to show the current song title in a medley. And it would be really good if it shows "trumpet solo by Chet Baker" while he is playing!
Jazz credits often say which order solos come
in, but currently if there are two different trumpet solos in one song
and two different credits with trumpet solo there is no way to state in Musicbrainz which is which (except with an annotation, of course).
-- "Times aren't exact anyway"
Sure. Tracks for the same recording can differ several seconds in length. But still, these times would be approximately right, which is quite enough.
-- "People wouldn't bother adding this anyway"
It would be extra work, so would only be added for stuff people care extra about. But hey, that which people care extra about to enter they also care extra about to have!
-- "Why 'sequence of timespans' instead of just 'a timespan'
It just seems more right. I'd much prefer one relation that John Doe has spoken vocal credit for 0:11--0:19 and 1:16--1:52 than to have that in two relations. Having two relations would break the DRY principle, and would for instance be less practical if John Doe should be corrected to another John Doe.