From a8602dde5e0a9858b9cee7e3788bef8efc43d950 Mon Sep 17 00:00:00 2001
From: Pedro Arthur <bygrandao@gmail.com>
Date: Fri, 25 Sep 2015 12:17:43 -0300
Subject: [PATCH] swscale: fix ticket #4877

---
 libswscale/swscale.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/libswscale/swscale.c b/libswscale/swscale.c
index 346728d9bd..2ccf38f3bb 100644
--- a/libswscale/swscale.c
+++ b/libswscale/swscale.c
@@ -480,17 +480,18 @@ static int swscale(SwsContext *c, const uint8_t *src[],
     ff_init_slice_from_src(vout_slice, (uint8_t**)dst, dstStride, c->dstW,
             dstY, dstH, dstY >> c->chrDstVSubSample,
             FF_CEIL_RSHIFT(dstH, c->chrDstVSubSample));
+    if (srcSliceY == 0) {
+        hout_slice->plane[0].sliceY = lastInLumBuf + 1;
+        hout_slice->plane[1].sliceY = lastInChrBuf + 1;
+        hout_slice->plane[2].sliceY = lastInChrBuf + 1;
+        hout_slice->plane[3].sliceY = lastInLumBuf + 1;
 
-    hout_slice->plane[0].sliceY = lastInLumBuf + 1;
-    hout_slice->plane[1].sliceY = lastInChrBuf + 1;
-    hout_slice->plane[2].sliceY = lastInChrBuf + 1;
-    hout_slice->plane[3].sliceY = lastInLumBuf + 1;
-
-    hout_slice->plane[0].sliceH =
-    hout_slice->plane[1].sliceH =
-    hout_slice->plane[2].sliceH =
-    hout_slice->plane[3].sliceH = 0;
-    hout_slice->width = dstW;
+        hout_slice->plane[0].sliceH =
+        hout_slice->plane[1].sliceH =
+        hout_slice->plane[2].sliceH =
+        hout_slice->plane[3].sliceH = 0;
+        hout_slice->width = dstW;
+    }
 #endif
 
     for (; dstY < dstH; dstY++) {