libavcodec/vc1dec.c:5070: error: Uninitialized Value
  The value read from yadv[_] was never initialized.

libavcodec/vc1dec.c:5070:17: 
5068.                 uint8_t *iplane = s->current_picture.f.data[plane];
5069.                 int      iline  = s->current_picture.f.linesize[plane];
5070.                 int      ycoord = yoff[sprite] + yadv[sprite] * row;
                      ^
5071.                 int      yline  = ycoord >> 16;
5072.                 ysub[sprite] = ycoord & 0xFFFF;
