ffmpeg.c:2797: error: Null Dereference
  pointer `mid` last assigned on line 2797 could be null and is dereferenced at line 2797, column 5.

ffmpeg.c:2789:1: start of procedure opt_metadata()
2787. }
2788. 
2789. static int opt_metadata(const char *opt, const char *arg)
      ^
2790. {
2791.     char *mid= strchr(arg, '=');

ffmpeg.c:2791:5: 
2789. static int opt_metadata(const char *opt, const char *arg)
2790. {
2791.     char *mid= strchr(arg, '=');
          ^
2792. 
2793.     if(!mid){

ffmpeg.c:2793:9: Taking true branch
2791.     char *mid= strchr(arg, '=');
2792. 
2793.     if(!mid){
              ^
2794.         fprintf(stderr, "Missing =\n");
2795.         ffmpeg_exit(1);

ffmpeg.c:2794:9: 
2792. 
2793.     if(!mid){
2794.         fprintf(stderr, "Missing =\n");
              ^
2795.         ffmpeg_exit(1);
2796.     }

ffmpeg.c:2795:9: Skipping ffmpeg_exit(): empty list of specs
2793.     if(!mid){
2794.         fprintf(stderr, "Missing =\n");
2795.         ffmpeg_exit(1);
              ^
2796.     }
2797.     *mid++= 0;

ffmpeg.c:2797:5: 
2795.         ffmpeg_exit(1);
2796.     }
2797.     *mid++= 0;
          ^
2798. 
2799.     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}']