ffmpeg: Free last_frame instead of just unref

Fixes Ticket4611

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit d1050d9950610aa2b27878b67bb2b902dd717e7c)

Conflicts:

	ffmpeg.c

1 files changed, 4 insertions, 1 deletions

diff --git a/ffmpeg.c b/ffmpeg.c
index bd75d4063d..a37bcd814b 100644
--- a/ffmpeg.c
+++ b/ffmpeg.c
@@ -1155,7 +1155,10 @@ static void do_video_out(AVFormatContext *s,
     if (!ost->last_frame)
         ost->last_frame = av_frame_alloc();
     av_frame_unref(ost->last_frame);
-    av_frame_ref(ost->last_frame, next_picture);
+    if (next_picture)
+        av_frame_ref(ost->last_frame, next_picture);
+    else
+        av_frame_free(&ost->last_frame);
 }
 
 static double psnr(double d)