[FFmpeg-cvslog] avcodec/zerocodec: Avoid undefined NULL - 0

[Andreas Rheinhardt]

ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinhardt at outlook.com> | Tue Sep 27 20:29:41 2022 +0200| [1e1ddbb70dd13c00c2e7378c17b3435325b856cf] | committer: Andreas Rheinhardt

avcodec/zerocodec: Avoid undefined NULL - 0

Fixes the zerocodec FATE-test.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=1e1ddbb70dd13c00c2e7378c17b3435325b856cf
---

 libavcodec/zerocodec.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/libavcodec/zerocodec.c b/libavcodec/zerocodec.c
index 93fc2834e4..42fb24ff6c 100644
--- a/libavcodec/zerocodec.c
+++ b/libavcodec/zerocodec.c
@@ -84,11 +84,12 @@ static int zerocodec_decode_frame(AVCodecContext *avctx, AVFrame *pic,
             return AVERROR_INVALIDDATA;
         }
 
-        if (!(avpkt->flags & AV_PKT_FLAG_KEY))
+        if (!(avpkt->flags & AV_PKT_FLAG_KEY)) {
             for (j = 0; j < avctx->width << 1; j++)
                 dst[j] += prev[j] & -!dst[j];
+            prev -= prev_pic->linesize[0];
+        }
 
-        prev -= prev_pic->linesize[0];
         dst  -= pic->linesize[0];
     }