ffmpeg.c:1781: error: Integer Overflow L2
  ([0, +oo] - 1):unsigned32 by call to `avfilter_unref_buffer`.

ffmpeg.c:1781:17: Call
1779.                               ist->out_video_filter && avfilter_poll_frame(ist->out_video_filter->inputs[0]);
1780.             if(ist->picref)
1781.                 avfilter_unref_buffer(ist->picref);
                      ^
1782.         }
1783. #endif

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: Assignment
  61. void avfilter_unref_buffer(AVFilterBufferRef *ref)
  62. {
  63.     if(!(--ref->buf->refcount))
               ^
  64.         ref->buf->free(ref->buf);
  65.     av_free(ref->video);

ffmpeg.c:1781:17: Call
1779.                               ist->out_video_filter && avfilter_poll_frame(ist->out_video_filter->inputs[0]);
1780.             if(ist->picref)
1781.                 avfilter_unref_buffer(ist->picref);
                      ^
1782.         }
1783. #endif

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, +oo] - 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);
