I guess this is dead easy, but given a filename/http url is it possible for me to add this directly to the playlist? I.e. if I haven't got it out of the metadb and thus don't have its metadb handle.

Use playlist_oper::add_location.

I'm trying to do the same thing but foobar seems to ignore it.

Possibly every my call to playlist_oper is ignored, because playlist_oper::get()->play_item(x) doesn't work for me as well.

Do I need to do something else pior to call? Does it matter where I call it from? (search on forum suggests that, but I have no idea how to call things from within foobar thread and how that is different from my components thread)