ffmpeg.c:2799: error: Null Dereference
  pointer `mid` last assigned on line 2799 could be null and is dereferenced at line 2799, column 5.

ffmpeg.c:2791:1: start of procedure opt_metadata()
2789. }
2790. 
2791. static int opt_metadata(const char *opt, const char *arg)
      ^
2792. {
2793.     char *mid= strchr(arg, '=');

ffmpeg.c:2793:5: 
2791. static int opt_metadata(const char *opt, const char *arg)
2792. {
2793.     char *mid= strchr(arg, '=');
          ^
2794. 
2795.     if(!mid){

ffmpeg.c:2795:9: Taking true branch
2793.     char *mid= strchr(arg, '=');
2794. 
2795.     if(!mid){
              ^
2796.         fprintf(stderr, "Missing =\n");
2797.         ffmpeg_exit(1);

ffmpeg.c:2796:9: 
2794. 
2795.     if(!mid){
2796.         fprintf(stderr, "Missing =\n");
              ^
2797.         ffmpeg_exit(1);
2798.     }

ffmpeg.c:2797:9: Skipping ffmpeg_exit(): empty list of specs
2795.     if(!mid){
2796.         fprintf(stderr, "Missing =\n");
2797.         ffmpeg_exit(1);
              ^
2798.     }
2799.     *mid++= 0;

ffmpeg.c:2799:5: 
2797.         ffmpeg_exit(1);
2798.     }
2799.     *mid++= 0;
          ^
2800. 
2801.     av_metadata_set2(&metadata, arg, mid, 0);

static int opt_metadata(const char *opt, const char *arg)
{
    char *mid= strchr(arg, '=');
    if(!mid){
        fprintf(stderr, "Missing =\n");
        ffmpeg_exit(1);
    }
    *mid++= 0;
    av_metadata_set2(&metadata, arg, mid, 0);
    return 0;
}
['static int opt_metadata(const char *opt, const char *arg)\n{\n    char *mid= strchr(arg, \'=\');\n    if(!mid){\n        fprintf(stderr, "Missing =\\n");\n        ffmpeg_exit(1);\n    }\n    *mid++= 0;\n    av_metadata_set2(&metadata, arg, mid, 0);\n    return 0;\n}']