libavfilter/vf_pad.c:393: error: Uninitialized Value
  The value read from bar_y was never initialized.

libavfilter/vf_pad.c:393:15: 
391.                           pad->line, pad->line_step, pad->hsub, pad->vsub,
392.                           0, bar_y, pad->w, bar_h);
393.         ret = ff_draw_slice(link->dst->outputs[0], bar_y, bar_h, slice_dir);
                   ^
394.     }
395.     return ret;
