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:435:32: 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:48:1: Parameter `ref->type`
  46. #define link_spad(link)     link->src->output_pads[link->srcpad]
  47. 
  48. AVFilterBufferRef *avfilter_ref_buffer(AVFilterBufferRef *ref, int pmask)
      ^
  49. {
  50.     AVFilterBufferRef *ret = av_malloc(sizeof(AVFilterBufferRef));

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:250:1: Parameter `picref->type`
  248. /* XXX: should we do the duplicating of the picture ref here, instead of
  249.  * forcing the source filter to do it? */
  250. void avfilter_start_frame(AVFilterLink *link, AVFilterBufferRef *picref)
       ^
  251. {
  252.     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:298:1: Parameter `link->cur_buf->linesize[*]`
  296. }
  297. 
  298. void avfilter_draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
       ^
  299. {
  300.     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:61:1: <LHS trace>
59. }
60. 
61. void avfilter_unref_buffer(AVFilterBufferRef *ref)
    ^
62. {
63.     if(!(--ref->buf->refcount))

libavfilter/avfilter.c:61:1: Parameter `ref->buf->refcount`
  59. }
  60. 
  61. void avfilter_unref_buffer(AVFilterBufferRef *ref)
      ^
  62. {
  63.     if(!(--ref->buf->refcount))

libavfilter/avfilter.c:63:10: Binary operation: (0 - 1):unsigned32 by call to `avfilter_unref_buffer` 
  61. void avfilter_unref_buffer(AVFilterBufferRef *ref)
  62. {
  63.     if(!(--ref->buf->refcount))
               ^
  64.         ref->buf->free(ref->buf);
  65.     av_free(ref->video);
