libavcodec/vc1dec.c:4294: error: Uninitialized Value
  The value read from interpmvp was never initialized.

libavcodec/vc1dec.c:4294:53: 
4292.                 get_mvdata_interlaced(v, &dmv_x[bmvtype == BMV_TYPE_BACKWARD], &dmv_y[bmvtype == BMV_TYPE_BACKWARD], &pred_flag[bmvtype == BMV_TYPE_BACKWARD]);
4293.             }
4294.             if (bmvtype == BMV_TYPE_INTERPOLATED && interpmvp) {
                                                          ^
4295.                 get_mvdata_interlaced(v, &dmv_x[1], &dmv_y[1], &pred_flag[1]);
4296.             }
