libavfilter/avfiltergraph.c:208: error: Integer Overflow L2
  ([0, +oo] - 1):unsigned32 by call to `pick_format`.

libavfilter/avfiltergraph.c:208:13: Call
206. 
207.         for (j = 0; j < filter->input_count; j++)
208.             pick_format(filter->inputs[j]);
                 ^
209.         for (j = 0; j < filter->output_count; j++)
210.             pick_format(filter->outputs[j]);

libavfilter/avfiltergraph.c:188:1: Parameter `link->out_formats->refcount`
  186. }
  187. 
  188. static void pick_format(AVFilterLink *link)
       ^
  189. {
  190.     if (!link || !link->in_formats)

libavfilter/avfiltergraph.c:208:13: Call
206. 
207.         for (j = 0; j < filter->input_count; j++)
208.             pick_format(filter->inputs[j]);
                 ^
209.         for (j = 0; j < filter->output_count; j++)
210.             pick_format(filter->outputs[j]);

libavfilter/avfiltergraph.c:188:1: Parameter `link->out_formats->refcount`
  186. }
  187. 
  188. static void pick_format(AVFilterLink *link)
       ^
  189. {
  190.     if (!link || !link->in_formats)

libavfilter/avfiltergraph.c:197:5: Call
  195. 
  196.     avfilter_formats_unref(&link->in_formats);
  197.     avfilter_formats_unref(&link->out_formats);
           ^
  198. }
  199. 

libavfilter/formats.c:137:1: <LHS trace>
135. }
136. 
137. void avfilter_formats_unref(AVFilterFormats **ref)
     ^
138. {
139.     int idx;

libavfilter/formats.c:137:1: Parameter `(*ref)->refcount`
    135. }
    136. 
    137. void avfilter_formats_unref(AVFilterFormats **ref)
         ^
    138. {
    139.     int idx;

libavfilter/formats.c:144:11: Call
    142.         return;
    143. 
    144.     idx = find_ref_index(ref);
                   ^
    145. 
    146.     if(idx >= 0)

libavfilter/formats.c:128:1: Parameter `(*ref)->refcount`
      126. }
      127. 
      128. static int find_ref_index(AVFilterFormats **ref)
           ^
      129. {
      130.     int i;

libavfilter/formats.c:150:9: Binary operation: ([0, +oo] - 1):unsigned32 by call to `pick_format` 
    148.             sizeof(AVFilterFormats**) * ((*ref)->refcount-idx-1));
    149. 
    150.     if(!--(*ref)->refcount) {
                 ^
    151.         av_free((*ref)->formats);
    152.         av_free((*ref)->refs);
