ffmpeg.c:2786: error: Null Dereference
  pointer `mid` last assigned on line 2786 could be null and is dereferenced at line 2786, column 5.

ffmpeg.c:2778:1: start of procedure opt_metadata()
2776. }
2777. 
2778. static int opt_metadata(const char *opt, const char *arg)
      ^
2779. {
2780.     char *mid= strchr(arg, '=');

ffmpeg.c:2780:5: 
2778. static int opt_metadata(const char *opt, const char *arg)
2779. {
2780.     char *mid= strchr(arg, '=');
          ^
2781. 
2782.     if(!mid){

ffmpeg.c:2782:9: Taking true branch
2780.     char *mid= strchr(arg, '=');
2781. 
2782.     if(!mid){
              ^
2783.         fprintf(stderr, "Missing =\n");
2784.         ffmpeg_exit(1);

ffmpeg.c:2783:9: 
2781. 
2782.     if(!mid){
2783.         fprintf(stderr, "Missing =\n");
              ^
2784.         ffmpeg_exit(1);
2785.     }

ffmpeg.c:2784:9: Skipping ffmpeg_exit(): empty list of specs
2782.     if(!mid){
2783.         fprintf(stderr, "Missing =\n");
2784.         ffmpeg_exit(1);
              ^
2785.     }
2786.     *mid++= 0;

ffmpeg.c:2786:5: 
2784.         ffmpeg_exit(1);
2785.     }
2786.     *mid++= 0;
          ^
2787. 
2788.     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}']