/Applications/Spotify.app/Contents/Resources/Spotify.sdef
# read-only
osascript -e 'tell application "Spotify" to player state' # stopped,playing,paused
osascript -e 'tell application "Spotify" to current track' # The current playing track.
osascript -e 'tell application "Spotify" to artwork of current track' # Image data in TIFF format.
osascript -e 'tell application "Spotify" to artist of current track' # The artist of the track.