libavcodec/vc1dec.c:688: error: Uninitialized Value
  The value read from mvy[_] was never initialized.

libavcodec/vc1dec.c:688:9: 
686.         for(i= t1+1; i<4; i++)if(!intra[i]) {t2 = i; break;}
687.         tx = (mvx[t1] + mvx[t2]) / 2;
688.         ty = (mvy[t1] + mvy[t2]) / 2;
             ^
689.     } else {
690.         s->current_picture.f.motion_val[1][s->block_index[0]][0] = 0;
