avcodec/mpegvideo_enc: dont use direct mode for unaligned input

Fixes Ticket3456
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/mpegvideo_enc.c

@@ -1039,6 +1039,10 @@ static int load_input_picture(MpegEncContext *s, const AVFrame *pic_arg)
             direct = 0;
         if ((s->width & 15) || (s->height & 15))
             direct = 0;
+        if (((intptr_t)(pic_arg->data[0])) & (STRIDE_ALIGN-1))
+            direct = 0;
+        if (s->linesize & (STRIDE_ALIGN-1))
+            direct = 0;
 
         av_dlog(s->avctx, "%d %d %td %td\n", pic_arg->linesize[0],
                 pic_arg->linesize[1], s->linesize, s->uvlinesize);