--- dashdec.c	2020-05-08 08:40:32 +0900
+++ dashdec2.c	2020-06-03 15:37:51 +0900
@@ -2001,6 +2001,7 @@
         st->id = i;
         avcodec_parameters_copy(st->codecpar, ist->codecpar);
         avpriv_set_pts_info(st, ist->pts_wrap_bits, ist->time_base.num, ist->time_base.den);
+        av_dict_copy(&st->metadata, ist->metadata, 0);
     }
 
     return 0;