swscale/swscale_unscaled: don't use the optimized bgr24toYV12 unscaled conversion when width%2

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Limin Wang <lance.lmwang@gmail.com>

libswscale/swscale_unscaled.c

@@ -1978,6 +1978,7 @@ void ff_get_unscaled_swscale(SwsContext *c)
     const enum AVPixelFormat dstFormat = c->dstFormat;
     const int flags = c->flags;
     const int dstH = c->dstH;
+    const int dstW = c->dstW;
     int needsDither;
 
     needsDither = isAnyRGB(dstFormat) &&
@@ -2033,7 +2034,7 @@ void ff_get_unscaled_swscale(SwsContext *c)
     /* bgr24toYV12 */
     if (srcFormat == AV_PIX_FMT_BGR24 &&
         (dstFormat == AV_PIX_FMT_YUV420P || dstFormat == AV_PIX_FMT_YUVA420P) &&
-        !(flags & SWS_ACCURATE_RND))
+        !(flags & SWS_ACCURATE_RND) && !(dstW&1))
         c->swscale = bgr24ToYv12Wrapper;
 
     /* RGB/BGR -> RGB/BGR (no dither needed forms) */