libavformat: Add a flag for muxers that support write_packet(NULL) for flushing

Signed-off-by: Martin Storsjö <martin@martin.st>

1 files changed, 9 insertions, 1 deletions

diff --git a/libavformat/utils.c b/libavformat/utils.c
index 22ee13b51f..093389b386 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -3135,7 +3135,15 @@ static int compute_pkt_fields2(AVFormatContext *s, AVStream *st, AVPacket *pkt){
 
 int av_write_frame(AVFormatContext *s, AVPacket *pkt)
 {
-    int ret = compute_pkt_fields2(s, s->streams[pkt->stream_index], pkt);
+    int ret;
+
+    if (!pkt) {
+        if (s->oformat->flags & AVFMT_ALLOW_FLUSH)
+            return s->oformat->write_packet(s, pkt);
+        return 1;
+    }
+
+    ret = compute_pkt_fields2(s, s->streams[pkt->stream_index], pkt);
 
     if(ret<0 && !(s->oformat->flags & AVFMT_NOTIMESTAMPS))
         return ret;