Make volume-change a void rather than a boolean

src/audio_output/intf.c

@@ -153,7 +153,7 @@ int doVolumeChanges( unsigned action, vlc_object_t * p_object, int i_nb_steps,
     }
 
     /* trigger callbacks */
-    var_SetBool( p_object->p_libvlc, "volume-change", true );
+    var_TriggerCallback( p_object->p_libvlc, "volume-change");
     if ( p_aout ) var_SetBool( p_aout, "intf-change", true );
 
     if ( p_aout )

src/libvlc.c

@@ -858,7 +858,7 @@ int libvlc_InternalInit( libvlc_int_t *p_libvlc, int i_argc,
      */
     /* Create volume callback system. (this variable must be created before
        all interfaces as they can use it) */
-    var_Create( p_libvlc, "volume-change", VLC_VAR_BOOL );
+    var_Create( p_libvlc, "volume-change", VLC_VAR_VOID );
     var_Create( p_libvlc, "volume-muted", VLC_VAR_BOOL );
 
     psz_modules = var_CreateGetNonEmptyString( p_libvlc, "extraintf" );