macOS High Sierra Media Key Enabler for iTunes and Spotify.
You can prioritize which app you would like to control or you can go with the default behaviour which controls the running app. The app runs in the menu bar in the form of a subtle and beautiful black dot. It only works with physical buttons, won't work with the TouchBar. Won't work with headphone remote buttons.
Version 1.5 :
- now you can explicitly prioritize iTunes or Spotify
- play button now starts up iTunes or Spotify if they are not running aaaand explicitly selected
Apple just released High Sierra and it brought good things and annoying things : they changed the behaviour of the media controller keys, they no longer control itunes, they control the video playback in safari. This pissed off a lot of people including me, so I just created a menu bar app to proxy media key events to iTunes/Spotify while Apple fixes this. It doesn't support touchbar yet, only physical buttons.