libavfilter/vf_pad.c:440: error: Integer Overflow L1
  (0 - 1):unsigned32 by call to `avfilter_unref_pic`.

libavfilter/vf_pad.c:432:5: Assignment
430.     picref->pixel_aspect = (AVRational) {1, 1};
431.     picref->pts          = av_rescale_q(color->pts++, color->time_base, AV_TIME_BASE_Q);
432.     picref->pos          = 0;
         ^
433. 
434.     avfilter_start_frame(link, avfilter_ref_pic(picref, ~0));

libavfilter/vf_pad.c:435:5: Call
433. 
434.     avfilter_start_frame(link, avfilter_ref_pic(picref, ~0));
435.     draw_rectangle(picref,
         ^
436.                    color->line, color->line_step, color->hsub, color->vsub,
437.                    0, 0, color->w, color->h);

libavfilter/vf_pad.c:85:1: Parameter `outpic->linesize[*]`
  83. }
  84. 
  85. static void draw_rectangle(AVFilterPicRef *outpic, uint8_t *line[4], int line_step[4],
      ^
  86.                            int hsub, int vsub, int x, int y, int w, int h)
  87. {

libavfilter/vf_pad.c:438:5: Call
436.                    color->line, color->line_step, color->hsub, color->vsub,
437.                    0, 0, color->w, color->h);
438.     avfilter_draw_slice(link, 0, color->h, 1);
         ^
439.     avfilter_end_frame(link);
440.     avfilter_unref_pic(picref);

libavfilter/avfilter.c:292:1: Parameter `link->cur_pic->linesize[*]`
  290. }
  291. 
  292. void avfilter_draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
       ^
  293. {
  294.     uint8_t *src[4], *dst[4];

libavfilter/vf_pad.c:440:5: Call
438.     avfilter_draw_slice(link, 0, color->h, 1);
439.     avfilter_end_frame(link);
440.     avfilter_unref_pic(picref);
         ^
441. 
442.     return 0;

libavfilter/avfilter.c:56:1: <LHS trace>
54. }
55. 
56. void avfilter_unref_pic(AVFilterPicRef *ref)
    ^
57. {
58.     if(!(--ref->pic->refcount))

libavfilter/avfilter.c:56:1: Parameter `ref->pic->refcount`
  54. }
  55. 
  56. void avfilter_unref_pic(AVFilterPicRef *ref)
      ^
  57. {
  58.     if(!(--ref->pic->refcount))

libavfilter/avfilter.c:58:10: Binary operation: (0 - 1):unsigned32 by call to `avfilter_unref_pic` 
  56. void avfilter_unref_pic(AVFilterPicRef *ref)
  57. {
  58.     if(!(--ref->pic->refcount))
               ^
  59.         ref->pic->free(ref->pic);
  60.     av_free(ref);
