For completeness sake, in the gnome environment the following are autostarted:
$ ps aux | grep tracker
31415 tc /usr/local/lib/tracker-2.0/tracker-miner-fs
31416 tc /usr/local/lib/tracker-2.0/tracker-miner-apps
31418 tc /usr/local/lib/tracker-2.0/tracker-extract
31439 tc /usr/local/lib/tracker-2.0/tracker-store
..you then have to enable the file types to be indexed in Settings - Search - Preferences [Videos, Music, Documents, Downloads, Home, Pictures].
Then check things work:
$ tracker search -m
Files:
file:///home/tc/Music/aayw.mp3
file:///home/tc/Music/terminator.wav
file:///home/tc/Music/Test_-_test1.mid
file:///home/tc/Music/Video_Games.flac
..and then gnome music will find and play music tracks
I'll add tracker-miners to the gnome-music deps in case anybody wants to try to start tracker manually and mess with gsettings/dconf-editor to enable music file search.
Note ironically, the last time I checked, at least one of gnome-{documents, music, photos, videos} will only "see" files found in $HOME/{Documents, Music, Pictures, Videos} regardless of where tracker finds appropriate files