libavcodec/vc1dec.c:5708: error: Uninitialized Value
  The value read from n_slices1 was never initialized.

libavcodec/vc1dec.c:5708:38: 
5706.             if (i) {
5707.                 v->pic_header_flag = 0;
5708.                 if (v->field_mode && i == n_slices1 + 2)
                                           ^
5709.                     ff_vc1_parse_frame_header_adv(v, &s->gb);
5710.                 else if (get_bits1(&s->gb)) {
