libavfilter/defaults.c:199: error: Integer Overflow L2
  ([0, +oo] - 1):unsigned32 by call to `avfilter_unref_buffer`.

libavfilter/defaults.c:199:13: Call
197.     if (out) {
198.         if (out->out_buf) {
199.             avfilter_unref_buffer(out->out_buf);
                 ^
200.             out->out_buf = NULL;
201.         }

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:77:11: Binary operation: ([0, +oo] - 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);

void avfilter_unref_buffer(AVFilterBufferRef *ref)
{
    if (!(--ref->buf->refcount))
        ref->buf->free(ref->buf);
    av_free(ref->video);
    av_free(ref->audio);
    av_free(ref);
}
['void avfilter_default_end_frame(AVFilterLink *link)\n{\n    AVFilterLink *out = NULL;\n    if (link->dst->output_count)\n        out = link->dst->outputs[0];\n    avfilter_unref_buffer(link->cur_buf);\n    link->cur_buf = NULL;\n    if (out) {\n        if (out->out_buf) {\n            avfilter_unref_buffer(out->out_buf);\n            out->out_buf = NULL;\n        }\n        avfilter_end_frame(out);\n    }\n}', 'void avfilter_unref_buffer(AVFilterBufferRef *ref)\n{\n    if (!(--ref->buf->refcount))\n        ref->buf->free(ref->buf);\n    av_free(ref->video);\n    av_free(ref->audio);\n    av_free(ref);\n}']