$ dbus-monitor --session "path=/org/mpris/MediaPlayer2,member=PropertiesChanged" --monitor
signal sender=org.freedesktop.DBus -> dest=:1.461 serial=2 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=NameAcquired
   string ":1.461"
signal sender=:1.128 -> dest=(null destination) serial=949 path=/org/mpris/MediaPlayer2; interface=org.freedesktop.DBus.Properties; member=PropertiesChanged
   string "org.mpris.MediaPlayer2.Player"
   array [
      dict entry(
         string "Volume"
         variant             double 0.50769
      )
   ]
   array [
   ]
signal sender=:1.128 -> dest=(null destination) serial=950 path=/org/mpris/MediaPlayer2; interface=org.freedesktop.DBus.Properties; member=PropertiesChanged
   string "org.mpris.MediaPlayer2.Player"
   array [
      dict entry(
         string "Volume"
         variant             double 0.50769
      )
   ]
   array [
   ]
signal sender=:1.128 -> dest=(null destination) serial=951 path=/org/mpris/MediaPlayer2; interface=org.freedesktop.DBus.Properties; member=PropertiesChanged
   string "org.mpris.MediaPlayer2.Player"
   array [
      dict entry(
         string "Volume"
         variant             double 0.50769
      )
   ]
   array [
   ]
signal sender=:1.128 -> dest=(null destination) serial=958 path=/org/mpris/MediaPlayer2; interface=org.freedesktop.DBus.Properties; member=PropertiesChanged
   string "org.mpris.MediaPlayer2.Player"
   array [
      dict entry(
         string "CanSeek"
         variant             boolean false
      )
      dict entry(
         string "Metadata"
         variant             array [
               dict entry(
                  string "mpris:trackid"
                  variant                      string "/org/mpris/MediaPlayer2/Track/993"
               )
               dict entry(
                  string "xesam:url"
                  variant                      string "file:///home/cweiske/Musik/Alben/Britney%20Spears/Oops!..%20I%20did%20it%20again/Britney%20Spears%20-%20Oops!..%20I%20did%20it%20again%20-%20Lucky.ogg"
               )
               dict entry(
                  string "xesam:title"
                  variant                      string "Lucky"
               )
               dict entry(
                  string "xesam:artist"
                  variant                      array [
                        string "Britney Spears"
                     ]
               )
               dict entry(
                  string "xesam:album"
                  variant                      string "Oops!..I Did It Again"
               )
               dict entry(
                  string "xesam:genre"
                  variant                      array [
                        string "Pop"
                     ]
               )
               dict entry(
                  string "xesam:audioBitrate"
                  variant                      int32 196608
               )
               dict entry(
                  string "xesam:contentCreated"
                  variant                      string "2000-01-01T00:00:00Z"
               )
               dict entry(
                  string "xesam:lastUsed"
                  variant                      string "2016-03-10T11:40:55Z"
               )
               dict entry(
                  string "mpris:length"
                  variant                      int64 206000000
               )
               dict entry(
                  string "xesam:trackNumber"
                  variant                      int32 0
               )
               dict entry(
                  string "xesam:useCount"
                  variant                      int32 3
               )
               dict entry(
                  string "xesam:userRating"
                  variant                      double 0
               )
               dict entry(
                  string "mpris:artUrl"
                  variant                      string "file:///home/cweiske/.cache/rhythmbox/album-art/00000029"
               )
            ]
      )
      dict entry(
         string "PlaybackStatus"
         variant             string "Playing"
      )
   ]
   array [
   ]