From 98e42a249e7891d295228ff19892450ba1f09092 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Sat, 2 Aug 2014 04:16:02 +0200
Subject: [PATCH] avformat/format: Check for av_guess_format() failure

Fixes null pointer dereference
Fixes Ticket3812

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
---
 libavformat/format.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/libavformat/format.c b/libavformat/format.c
index 238a13acd4..1c25d6b933 100644
--- a/libavformat/format.c
+++ b/libavformat/format.c
@@ -145,7 +145,9 @@ enum AVCodecID av_guess_codec(AVOutputFormat *fmt, const char *short_name,
                               enum AVMediaType type)
 {
     if (av_match_name("segment", fmt->name) || av_match_name("ssegment", fmt->name)) {
-        fmt = av_guess_format(NULL, filename, NULL);
+        AVOutputFormat *fmt2 = av_guess_format(NULL, filename, NULL);
+        if (fmt2)
+            fmt = fmt2;
     }
 
     if (type == AVMEDIA_TYPE_VIDEO) {