ffmpeg.c:2617: error: Null Dereference
  pointer `mid` last assigned on line 2617 could be null and is dereferenced at line 2617, column 5.

ffmpeg.c:2609:1: start of procedure opt_metadata()
2607. }
2608. 
2609. static int opt_metadata(const char *opt, const char *arg)
      ^
2610. {
2611.     char *mid= strchr(arg, '=');

ffmpeg.c:2611:5: 
2609. static int opt_metadata(const char *opt, const char *arg)
2610. {
2611.     char *mid= strchr(arg, '=');
          ^
2612. 
2613.     if(!mid){

ffmpeg.c:2613:9: Taking true branch
2611.     char *mid= strchr(arg, '=');
2612. 
2613.     if(!mid){
              ^
2614.         fprintf(stderr, "Missing =\n");
2615.         av_exit(1);

ffmpeg.c:2614:9: 
2612. 
2613.     if(!mid){
2614.         fprintf(stderr, "Missing =\n");
              ^
2615.         av_exit(1);
2616.     }

ffmpeg.c:2615:9: Skipping av_exit(): empty list of specs
2613.     if(!mid){
2614.         fprintf(stderr, "Missing =\n");
2615.         av_exit(1);
              ^
2616.     }
2617.     *mid++= 0;

ffmpeg.c:2617:5: 
2615.         av_exit(1);
2616.     }
2617.     *mid++= 0;
          ^
2618. 
2619.     metadata_count++;

static int opt_metadata(const char *opt, const char *arg)
{
    char *mid= strchr(arg, '=');
    if(!mid){
        fprintf(stderr, "Missing =\n");
        av_exit(1);
    }
    *mid++= 0;
    metadata_count++;
    metadata= av_realloc(metadata, sizeof(*metadata)*metadata_count);
    metadata[metadata_count-1].key  = av_strdup(arg);
    metadata[metadata_count-1].value= av_strdup(mid);
    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        av_exit(1);\n    }\n    *mid++= 0;\n    metadata_count++;\n    metadata= av_realloc(metadata, sizeof(*metadata)*metadata_count);\n    metadata[metadata_count-1].key  = av_strdup(arg);\n    metadata[metadata_count-1].value= av_strdup(mid);\n    return 0;\n}']