Merge commit 'f812eeda17e38797df5cb733ce99cdfd829d84ca'

* commit 'f812eeda17e38797df5cb733ce99cdfd829d84ca':
  matroskaenc: Fix writing TRACKDEFAULTFLAG

Conflicts:
	libavformat/matroskaenc.c
	tests/fate/wavpack.mak
	tests/ref/lavf/mkv
	tests/ref/seek/lavf-mkv

Merged-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/matroskaenc.c

@@ -613,9 +613,11 @@ static int mkv_write_tracks(AVFormatContext *s)
             put_ebml_string(pb, MATROSKA_ID_TRACKLANGUAGE, tag->value);
         }
 
-        if (default_stream_exists) {
+        // The default value for TRACKFLAGDEFAULT is 1, so add element
+        // if we need to clear it.
+        if (default_stream_exists && !(st->disposition & AV_DISPOSITION_DEFAULT))
             put_ebml_uint(pb, MATROSKA_ID_TRACKFLAGDEFAULT, !!(st->disposition & AV_DISPOSITION_DEFAULT));
-        }
+
         if (st->disposition & AV_DISPOSITION_FORCED)
             put_ebml_uint(pb, MATROSKA_ID_TRACKFLAGFORCED, 1);