libavcodec/mpegvideo.c:870: error: Uninitialized Value
  The value read from y_size was never initialized.

libavcodec/mpegvideo.c:870:13: 
868.                               yc_size * sizeof(int16_t), fail);
869.             s->dc_val[0] = s->dc_val_base + s->b8_stride + 1;
870.             s->dc_val[1] = s->dc_val_base + y_size + s->mb_stride + 1;
                 ^
871.             s->dc_val[2] = s->dc_val[1] + c_size;
872.             for (i = 0; i < yc_size; i++)
