mkv: Flush the old cluster before writing a new one

This simplifies keeping track of cluster boundaries for e.g.
livestreaming of WebM.

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index ead0a82467..51edce0152 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -1315,6 +1315,7 @@ static int mkv_write_packet(AVFormatContext *s, AVPacket *pkt)
         mkv->cluster_pos = 0;
         if (mkv->dyn_bc)
             mkv_flush_dynbuf(s);
+        avio_flush(s->pb);
     }
 
     // check if we have an audio packet cached