Merge commit '9ad1e0c12caa440de860bd8f2122beb11d73815c'

* commit '9ad1e0c12caa440de860bd8f2122beb11d73815c':
  mux: Make sure that the data is actually written

Merged-by: Hendrik Leppkes <h.leppkes@gmail.com>

libavformat/mux.c

@@ -660,8 +660,13 @@ static int write_packet(AVFormatContext *s, AVPacket *pkt)
         ret = s->oformat->write_packet(s, pkt);
     }
 
-    if (s->flush_packets && s->pb && ret >= 0 && s->flags & AVFMT_FLAG_FLUSH_PACKETS)
-        avio_flush(s->pb);
+    if (s->pb && ret >= 0) {
+        if (s->flush_packets && s->flags & AVFMT_FLAG_FLUSH_PACKETS)
+            avio_flush(s->pb);
+        if (s->pb->error < 0)
+            ret = s->pb->error;
+    }
+
 
     if (did_split)
         av_packet_merge_side_data(pkt);