public override object GetGroupByValue(MediaItem item)
 {
     if (_grouping != null)
     {
         return(_grouping.GetGroupByValue(item));
     }
     return(null);
 }
        public object GetGroupingValue(object item)
        {
            if (CurrentGrouping == null)
            {
                return(null);
            }
            var pmi = item as PlayableMediaItem;

            if (pmi != null)
            {
                item = pmi.MediaItem;
            }
            var mi = item as MediaItem;

            if (mi != null)
            {
                return(CurrentGrouping.GetGroupByValue(mi));
            }
            return(null);
        }