diff --git a/libse/BluRaySup/BluRaySupPicture.cs b/libse/BluRaySup/BluRaySupPicture.cs
index 53ad4c87c..f082cb6a3 100644
--- a/libse/BluRaySup/BluRaySupPicture.cs
+++ b/libse/BluRaySup/BluRaySupPicture.cs
@@ -263,7 +263,7 @@ namespace Nikse.SubtitleEdit.Core.BluRaySup
         /// <summary>
         /// Create the binary stream representation of one caption
         /// </summary>
-        /// <param name="pic">SubPicture object containing caption info</param>
+        /// <param name="pic">SubPicture object containing caption info - note that first Composition Number should be 0, then 2, 4, 8, etc.</param>
         /// <param name="bmp">Bitmap</param>
         /// <param name="fps">Frames per second</param>
         /// <param name="bottomMargin">Image bottom margin</param>
diff --git a/src/Forms/ExportPngXml.cs b/src/Forms/ExportPngXml.cs
index 78547fe88..636d35070 100644
--- a/src/Forms/ExportPngXml.cs
+++ b/src/Forms/ExportPngXml.cs
@@ -264,7 +264,8 @@ namespace Nikse.SubtitleEdit.Forms
                 EndTime = (long)param.P.EndTime.TotalMilliseconds,
                 Width = param.ScreenWidth,
                 Height = param.ScreenHeight,
-                IsForced = param.Forced
+                IsForced = param.Forced,
+                CompositionNumber = param.P.Number * 2
             };
             if (param.FullFrame)
             {