ffmpeg.c:1782: error: Integer Overflow L2
  ([0, +oo] - 1):unsigned32 by call to `avfilter_unref_pic`.

ffmpeg.c:1782:17: Call
1780.                               ist->out_video_filter && avfilter_poll_frame(ist->out_video_filter->inputs[0]);
1781.             if(ist->picref)
1782.                 avfilter_unref_pic(ist->picref);
                      ^
1783.         }
1784. #endif

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: Assignment
  56. void avfilter_unref_pic(AVFilterPicRef *ref)
  57. {
  58.     if(!(--ref->pic->refcount))
               ^
  59.         ref->pic->free(ref->pic);
  60.     av_free(ref);

ffmpeg.c:1782:17: Call
1780.                               ist->out_video_filter && avfilter_poll_frame(ist->out_video_filter->inputs[0]);
1781.             if(ist->picref)
1782.                 avfilter_unref_pic(ist->picref);
                      ^
1783.         }
1784. #endif

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, +oo] - 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);
