matroskaenc: don't write an empty Cues element.

1 files changed, 6 insertions, 3 deletions

diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index e28ac42a75..c0427f9854 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -1140,10 +1140,13 @@ static int mkv_write_trailer(AVFormatContext *s)
     }
 
     if (pb->seekable) {
-        cuespos = mkv_write_cues(pb, mkv->cues, s->nb_streams);
+        if (mkv->cues->num_entries) {
+            cuespos = mkv_write_cues(pb, mkv->cues, s->nb_streams);
+
+            ret = mkv_add_seekhead_entry(mkv->main_seekhead, MATROSKA_ID_CUES, cuespos);
+            if (ret < 0) return ret;
+        }
 
-        ret = mkv_add_seekhead_entry(mkv->main_seekhead, MATROSKA_ID_CUES    , cuespos);
-        if (ret < 0) return ret;
         mkv_write_seekhead(pb, mkv->main_seekhead);
 
         // update the duration