Audio normalization (#9222)

Co-authored-by: Joe Rogers <1337joe@users.noreply.github.com>
Co-authored-by: Bond-009 <bond.009@outlook.com>

MediaBrowser.Controller/Entities/BaseItem.cs

@@ -128,6 +128,13 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         public string Album { get; set; }
 
+        /// <summary>
+        /// Gets or sets the LUFS value.
+        /// </summary>
+        /// <value>The LUFS Value.</value>
+        [JsonIgnore]
+        public float LUFS { get; set; }
+
         /// <summary>
         /// Gets or sets the channel identifier.
         /// </summary>