slackbuilds/multimedia/playerctl/README

playerctl (MPRIS media player controller and lib for spotify, vlc, 
audacious, bmp, xmms2, and others)

Playerctl is a command-line utility and library for controlling media 
players that implement the MPRIS  D-Bus Interface Specification: 
http://specifications.freedesktop.org/mpris-spec/latest/

Playerctl makes it easy to bind player actions, such as play and pause, 
to media keys.