I had originally written a Lyric API as a hobby project way back using Node. I published it on github as a combination of API server hosted on heroku along with a library hosted on NPM. It still gets 50 downloads a week and the hosted heroku API server is actually used by many people even though it offers little to no functionality. I was recently looking at wtf dashboard and even contributed a small patch to it.
xfce4 has default media key settings for Pragha music player. Although, if you use clementine music player you can use keyboard shortcuts to control it with DBus and MPRIS. Clementine is known as org.mpris.clementine and you can add the following entries to your Keyboard Settings > Application Shortcuts If you use spotify, it is registered as org.mpris.MediaPlayer2.spotify on qdbus. qdbus org.mpris.clementine /Player org.freedesktop.MediaPlayer.Next qdbus org.mpris.clementine /Player org.freedesktop.MediaPlayer.Pause qdbus org.mpris.clementine /Player org.