diff --git a/libnymea/interfaces/extendedmediacontroller.json b/libnymea/interfaces/extendedmediacontroller.json
deleted file mode 100644
index 1473da78..00000000
--- a/libnymea/interfaces/extendedmediacontroller.json
+++ /dev/null
@@ -1,12 +0,0 @@
-{
-    "description": "A more advanced media controller interface, supporting fast forward and rewind",
-    "extends": "mediacontroller",
-    "actions": [
-        {
-            "name": "fastRewind"
-        },
-        {
-            "name": "fastForward"
-        }
-    ]
-}
diff --git a/libnymea/interfaces/extendedvolumecontroller.json b/libnymea/interfaces/extendedvolumecontroller.json
deleted file mode 100644
index 59294ba9..00000000
--- a/libnymea/interfaces/extendedvolumecontroller.json
+++ /dev/null
@@ -1,17 +0,0 @@
-{
-    "extends": "media",
-    "states": [
-        {
-            "name": "mute",
-            "type": "bool",
-            "writable": true
-        },
-        {
-            "name": "volume",
-            "type": "int",
-            "minValue": 0,
-            "maxValue": 100,
-            "writable": true
-        }
-    ]
-}
diff --git a/libnymea/interfaces/interfaces.qrc b/libnymea/interfaces/interfaces.qrc
index 4e6c2c0f..c0fe0fb8 100644
--- a/libnymea/interfaces/interfaces.qrc
+++ b/libnymea/interfaces/interfaces.qrc
@@ -18,13 +18,10 @@
         <file>notifications.json</file>
         <file>weather.json</file>
         <file>volumecontroller.json</file>
-        <file>extendedvolumecontroller.json</file>
         <file>media.json</file>
         <file>mediacontroller.json</file>
-        <file>extendedmediacontroller.json</file>
         <file>mediametadataprovider.json</file>
         <file>mediaplayer.json</file>
-        <file>shufflerepeat.json</file>
         <file>battery.json</file>
         <file>batterylevel.json</file>
         <file>button.json</file>
diff --git a/libnymea/interfaces/mediacontroller.json b/libnymea/interfaces/mediacontroller.json
index 45a2e404..d4d1d710 100644
--- a/libnymea/interfaces/mediacontroller.json
+++ b/libnymea/interfaces/mediacontroller.json
@@ -1,6 +1,40 @@
 {
-    "description": "The mediacontroller interface contains basic actions to control media streams. If a device supports fast forward and rewind, use extendedmediacontroller instead.",
+    "description": "The mediacontroller interface contains actions to control media streams.",
     "extends": "media",
+    "states": [
+        {
+            "name": "shuffle",
+            "type": "bool",
+            "writable": true,
+            "optional": true
+        },
+        {
+            "name": "repeat",
+            "type": "QString",
+            "allowedValues": ["None", "One", "All"],
+            "writable": true,
+            "optional": true
+        },
+        {
+            "name": "like",
+            "type": "bool",
+            "writable": true,
+            "optional": true
+        },
+        {
+            "name": "equalizerPreset",
+            "type": "QString",
+            "allowedValues": "any",
+            "writable": true,
+            "optional": true
+        },
+        {
+            "name": "nightMode",
+            "type": "bool",
+            "writable": true,
+            "optional": true
+        }
+    ],
     "actions": [
         {
             "name": "skipBack"
@@ -16,6 +50,14 @@
         },
         {
             "name": "skipNext"
+        },
+        {
+            "name": "fastForward",
+            "optional": true
+        },
+        {
+            "name": "fastRewind",
+            "optional": true
         }
     ]
 }
diff --git a/libnymea/interfaces/mediaplayer.json b/libnymea/interfaces/mediaplayer.json
index 3db46bf4..5dda2700 100644
--- a/libnymea/interfaces/mediaplayer.json
+++ b/libnymea/interfaces/mediaplayer.json
@@ -1,5 +1,5 @@
 {
-    "description": "Media player interface. Used by devices/services which can play back media.",
+    "description": "Media player interface. Used by devices/services which can play back media. Even if a device only supports e.g. audio, the playerType state must still be added to the metadata. It may default to a single value and never change in this case. Players supporting duration and play time should provide those values in seconds.",
     "extends": "media",
     "states": [
         {
@@ -11,6 +11,25 @@
             "name": "playerType",
             "type": "QString",
             "allowedValues": ["audio", "video"]
+        },
+        {
+            "name": "inputSource",
+            "type": "QString",
+            "allowedValues": "any",
+            "writable": true,
+            "optional": true
+        },
+        {
+            "name": "playDuration",
+            "type": "uint",
+            "unit": "Seconds",
+            "optional": true
+        },
+        {
+            "name": "playTime",
+            "type": "uint",
+            "unit": "Seconds",
+            "optional": true
         }
     ]
 }
diff --git a/libnymea/interfaces/shufflerepeat.json b/libnymea/interfaces/shufflerepeat.json
deleted file mode 100644
index c96fdc63..00000000
--- a/libnymea/interfaces/shufflerepeat.json
+++ /dev/null
@@ -1,16 +0,0 @@
-{
-    "description": "Devices/services supporting this interface can control reproduction flow. E.g. a media controller, but could also be used by light scenes or other workflows",
-    "states": [
-        {
-            "name": "shuffle",
-            "type": "bool",
-            "writable": true
-        },
-        {
-            "name": "repeat",
-            "type": "QString",
-            "allowedValues": ["None", "One", "All"],
-            "writable": true
-        }
-    ]
-}
diff --git a/libnymea/interfaces/volumecontroller.json b/libnymea/interfaces/volumecontroller.json
index c90fb524..7f853250 100644
--- a/libnymea/interfaces/volumecontroller.json
+++ b/libnymea/interfaces/volumecontroller.json
@@ -1,33 +1,28 @@
 {
+    "desciption": "A volume controller allows to control volume and mute. At the very least, increaseVolume and decreaseVolume are to be implemented for devices that don't have a way to fetch the current volume. For devices allowing to set an absolute volume value, the volume and mute states should be implemented as well.",
     "extends": "media",
+    "states": [
+        {
+            "name": "mute",
+            "type": "bool",
+            "writable": true,
+            "optional": true
+        },
+        {
+            "name": "volume",
+            "type": "int",
+            "minValue": "any",
+            "maxValue": "any",
+            "writable": true,
+            "optional": true
+        }
+    ],
     "actions": [
         {
-            "name": "increaseVolume",
-            "params": [
-                {
-                    "name": "step",
-                    "type": "int"
-                }
-            ]
+            "name": "increaseVolume"
         },
         {
-            "name": "decreaseVolume",
-            "params": [
-                {
-                    "name": "step",
-                    "type": "int"
-                }
-            ]
-        },
-        {
-            "name": "setMute",
-            "params": [
-                {
-                    "name": "mute",
-                    "type": "bool"
-                }
-
-            ]
+            "name": "decreaseVolume"
         }
     ]
 }