libavfilter/defaults.c:105: error: Integer Overflow L2
  ([0, +oo] - 1):unsigned32 by call to `avfilter_unref_buffer`.

libavfilter/defaults.c:105:13: Call
103.     if(out) {
104.         if(out->out_buf) {
105.             avfilter_unref_buffer(out->out_buf);
                 ^
106.             out->out_buf = NULL;
107.         }

libavfilter/avfilter.c:57:1: <LHS trace>
55. }
56. 
57. void avfilter_unref_buffer(AVFilterBufferRef *ref)
    ^
58. {
59.     if(!(--ref->buf->refcount))

libavfilter/avfilter.c:57:1: Parameter `ref->buf->refcount`
  55. }
  56. 
  57. void avfilter_unref_buffer(AVFilterBufferRef *ref)
      ^
  58. {
  59.     if(!(--ref->buf->refcount))

libavfilter/avfilter.c:59:10: Binary operation: ([0, +oo] - 1):unsigned32 by call to `avfilter_unref_buffer` 
  57. void avfilter_unref_buffer(AVFilterBufferRef *ref)
  58. {
  59.     if(!(--ref->buf->refcount))
               ^
  60.         ref->buf->free(ref->buf);
  61.     av_free(ref);
