fixes #1290 - upgrade audio formats

MediaBrowser.Model/Net/MimeTypes.cs

@@ -238,7 +238,11 @@ namespace MediaBrowser.Model.Net
             if (StringHelper.EqualsIgnoreCase(ext, ".oga"))
             {
                 return "audio/ogg";
-            }
+			}
+			if (StringHelper.EqualsIgnoreCase(ext, ".opus"))
+			{
+				return "audio/opus";
+			}
 
             // Playlists
             if (StringHelper.EqualsIgnoreCase(ext, ".m3u8"))