swscale: fix crash with swscale-test when using slices

libswscale/swscale_unscaled.c

@@ -575,7 +575,7 @@ static int Rgb16ToPlanarRgb16Wrapper(SwsContext *c, const uint8_t *src[],
     case AV_PIX_FMT_RGB48BE:
     case AV_PIX_FMT_RGBA64LE:
     case AV_PIX_FMT_RGBA64BE:
-        packed16togbra16(src[0] + srcSliceY * srcStride[0], srcStride[0],
+        packed16togbra16(src[0], srcStride[0],
                          dst2013, stride2013, srcSliceH, alpha, swap,
                          16 - bpc, c->srcW);
         break;
@@ -583,7 +583,7 @@ static int Rgb16ToPlanarRgb16Wrapper(SwsContext *c, const uint8_t *src[],
     case AV_PIX_FMT_BGR48BE:
     case AV_PIX_FMT_BGRA64LE:
     case AV_PIX_FMT_BGRA64BE:
-        packed16togbra16(src[0] + srcSliceY * srcStride[0], srcStride[0],
+        packed16togbra16(src[0], srcStride[0],
                          dst1023, stride1023, srcSliceH, alpha, swap,
                          16 - bpc, c->srcW);
         break;