avconv.c:2669: error: Null Dereference
  pointer `mid` last assigned on line 2669 could be null and is dereferenced at line 2669, column 5.

avconv.c:2661:1: start of procedure opt_metadata()
2659. }
2660. 
2661. static int opt_metadata(const char *opt, const char *arg)
      ^
2662. {
2663.     char *mid= strchr(arg, '=');

avconv.c:2663:5: 
2661. static int opt_metadata(const char *opt, const char *arg)
2662. {
2663.     char *mid= strchr(arg, '=');
          ^
2664. 
2665.     if(!mid){

avconv.c:2665:9: Taking true branch
2663.     char *mid= strchr(arg, '=');
2664. 
2665.     if(!mid){
              ^
2666.         fprintf(stderr, "Missing =\n");
2667.         exit_program(1);

avconv.c:2666:9: 
2664. 
2665.     if(!mid){
2666.         fprintf(stderr, "Missing =\n");
              ^
2667.         exit_program(1);
2668.     }

avconv.c:2667:9: Skipping exit_program(): empty list of specs
2665.     if(!mid){
2666.         fprintf(stderr, "Missing =\n");
2667.         exit_program(1);
              ^
2668.     }
2669.     *mid++= 0;

avconv.c:2669:5: 
2667.         exit_program(1);
2668.     }
2669.     *mid++= 0;
          ^
2670. 
2671.     av_dict_set(&metadata, arg, mid, 0);
