libavcodec/vc1dec.c:3438: error: Uninitialized Value
  The value read from yadv[_] was never initialized.

libavcodec/vc1dec.c:3438:17: 
3436.                 uint8_t *iplane = s->current_picture.f.data[plane];
3437.                 int      iline  = s->current_picture.f.linesize[plane];
3438.                 int      ycoord = yoff[sprite] + yadv[sprite]*row;
                      ^
3439.                 int      yline  = ycoord>>16;
3440.                 ysub[sprite] = ycoord&0xFFFF;
