avformat/assenc: make sure we crawl extradata only if it's non-null

diff --git a/libavformat/assenc.c b/libavformat/assenc.c
index 8593b6ca4d9a070913c01bc01ac60a11992ca173..d495ce3a9223adab47f0cf44482d6bd5eee449a3 100644 (file)
--- a/libavformat/assenc.c
+++ b/libavformat/assenc.c
@@ -53,9 +53,9 @@ static int write_header(AVFormatContext *s)
         avio_write(s->pb, avctx->extradata, avctx->extradata_size);
         if (avctx->extradata[avctx->extradata_size - 1] != '\n')
             avio_write(s->pb, "\r\n", 2);
+        if (!strstr(avctx->extradata, "\n[Events]"))
+            avio_printf(s->pb, "[Events]\r\nFormat: Layer, Start, End, Style, Actor, MarginL, MarginR, MarginV, Effect, Text\r\n");
     }
-    if (!strstr(avctx->extradata, "\n[Events]"))
-        avio_printf(s->pb, "[Events]\r\nFormat: Layer, Start, End, Style, Actor, MarginL, MarginR, MarginV, Effect, Text\r\n");
     avio_flush(s->pb);
 
     return 0;