libavfilter/vf_pad.c:441: error: Integer Overflow L1
  (0 - 1):unsigned32 by call to `avfilter_unref_buffer`.

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

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

libavfilter/avfilter.c:286:1: Parameter `picref->type`
  284. /* XXX: should we do the duplicating of the picture ref here, instead of
  285.  * forcing the source filter to do it? */
  286. void avfilter_start_frame(AVFilterLink *link, AVFilterBufferRef *picref)
       ^
  287. {
  288.     void (*start_frame)(AVFilterLink *, AVFilterBufferRef *);

libavfilter/vf_pad.c:436:5: Call
434. 
435.     avfilter_start_frame(link, avfilter_ref_buffer(picref, ~0));
436.     draw_rectangle(picref,
         ^
437.                    color->line, color->line_step, color->hsub, color->vsub,
438.                    0, 0, color->w, color->h);

libavfilter/vf_pad.c:86:1: Parameter `outpic->linesize[*]`
  84. }
  85. 
  86. static void draw_rectangle(AVFilterBufferRef *outpic, uint8_t *line[4], int line_step[4],
      ^
  87.                            int hsub, int vsub, int x, int y, int w, int h)
  88. {

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

libavfilter/avfilter.c:334:1: Parameter `link->cur_buf->linesize[*]`
  332. }
  333. 
  334. void avfilter_draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
       ^
  335. {
  336.     uint8_t *src[4], *dst[4];

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

libavfilter/avfilter.c:75:1: <LHS trace>
73. }
74. 
75. void avfilter_unref_buffer(AVFilterBufferRef *ref)
    ^
76. {
77.     if(!(--ref->buf->refcount))

libavfilter/avfilter.c:75:1: Parameter `ref->buf->refcount`
  73. }
  74. 
  75. void avfilter_unref_buffer(AVFilterBufferRef *ref)
      ^
  76. {
  77.     if(!(--ref->buf->refcount))

libavfilter/avfilter.c:77:10: Binary operation: (0 - 1):unsigned32 by call to `avfilter_unref_buffer` 
  75. void avfilter_unref_buffer(AVFilterBufferRef *ref)
  76. {
  77.     if(!(--ref->buf->refcount))
               ^
  78.         ref->buf->free(ref->buf);
  79.     av_free(ref->video);
