ffmpeg.c:2769: error: Null Dereference
  pointer `mid` last assigned on line 2769 could be null and is dereferenced at line 2769, column 5.

ffmpeg.c:2761:1: start of procedure opt_metadata()
2759. }
2760. 
2761. static int opt_metadata(const char *opt, const char *arg)
      ^
2762. {
2763.     char *mid= strchr(arg, '=');

ffmpeg.c:2763:5: 
2761. static int opt_metadata(const char *opt, const char *arg)
2762. {
2763.     char *mid= strchr(arg, '=');
          ^
2764. 
2765.     if(!mid){

ffmpeg.c:2765:9: Taking true branch
2763.     char *mid= strchr(arg, '=');
2764. 
2765.     if(!mid){
              ^
2766.         fprintf(stderr, "Missing =\n");
2767.         ffmpeg_exit(1);

ffmpeg.c:2766:9: 
2764. 
2765.     if(!mid){
2766.         fprintf(stderr, "Missing =\n");
              ^
2767.         ffmpeg_exit(1);
2768.     }

ffmpeg.c:2767:9: Skipping ffmpeg_exit(): empty list of specs
2765.     if(!mid){
2766.         fprintf(stderr, "Missing =\n");
2767.         ffmpeg_exit(1);
              ^
2768.     }
2769.     *mid++= 0;

ffmpeg.c:2769:5: 
2767.         ffmpeg_exit(1);
2768.     }
2769.     *mid++= 0;
          ^
2770. 
2771.     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}']