From 39df4d24751d89af749e79f5839b341ad7931751 Mon Sep 17 00:00:00 2001
From: Paul B Mahol <onemda@gmail.com>
Date: Mon, 28 Sep 2015 20:53:01 +0200
Subject: [PATCH] avcodec/pngdec: reset has_trns after every decode_frame_png()

Fixes #4887.

Signed-off-by: Paul B Mahol <onemda@gmail.com>
(cherry picked from commit 1d0487f77f07663c510207eb6e946675b71823cb)
---
 libavcodec/pngdec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
index ee11f1249a..1b47b18361 100644
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@@ -1254,7 +1254,7 @@ static int decode_frame_png(AVCodecContext *avctx,
         return AVERROR_INVALIDDATA;
     }
 
-    s->y = s->state = 0;
+    s->y = s->state = s->has_trns = 0;
 
     /* init the zlib */
     s->zstream.zalloc = ff_png_zalloc;