add dlna service methods

MediaBrowser.Model/Entities/MediaStream.cs

@@ -123,6 +123,12 @@ namespace MediaBrowser.Model.Entities
         /// <value>The filename.</value>
         public string Path { get; set; }
 
+        /// <summary>
+        /// Gets or sets the pixel format.
+        /// </summary>
+        /// <value>The pixel format.</value>
+        public string PixelFormat { get; set; }
+        
         /// <summary>
         /// Gets or sets the level.
         /// </summary>