avformat/mov: don't mark an item referenced by a grid as dependent if it's the primary item

If it's the primary item, then it's expected to be ready for presentation even
outside of the grid it belongs to.

Signed-off-by: James Almer <jamrial@gmail.com>

libavformat/mov.c

@@ -9443,7 +9443,8 @@ static int mov_parse_tiles(AVFormatContext *s)
                 if (err < 0 && err != AVERROR(EEXIST))
                     return err;
 
-                st->disposition |= AV_DISPOSITION_DEPENDENT;
+                if (item->item_id != mov->primary_item_id)
+                    st->disposition |= AV_DISPOSITION_DEPENDENT;
                 break;
             }