ffmpeg.c:2543: error: Null Dereference
  pointer `mid` last assigned on line 2543 could be null and is dereferenced at line 2543, column 5.

ffmpeg.c:2535:1: start of procedure opt_metadata()
2533. }
2534. 
2535. static int opt_metadata(const char *opt, const char *arg)
      ^
2536. {
2537.     char *mid= strchr(arg, '=');

ffmpeg.c:2537:5: 
2535. static int opt_metadata(const char *opt, const char *arg)
2536. {
2537.     char *mid= strchr(arg, '=');
          ^
2538. 
2539.     if(!mid){

ffmpeg.c:2539:9: Taking true branch
2537.     char *mid= strchr(arg, '=');
2538. 
2539.     if(!mid){
              ^
2540.         fprintf(stderr, "Missing =\n");
2541.         av_exit(1);

ffmpeg.c:2540:9: 
2538. 
2539.     if(!mid){
2540.         fprintf(stderr, "Missing =\n");
              ^
2541.         av_exit(1);
2542.     }

ffmpeg.c:2541:9: Skipping av_exit(): empty list of specs
2539.     if(!mid){
2540.         fprintf(stderr, "Missing =\n");
2541.         av_exit(1);
              ^
2542.     }
2543.     *mid++= 0;

ffmpeg.c:2543:5: 
2541.         av_exit(1);
2542.     }
2543.     *mid++= 0;
          ^
2544. 
2545.     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}']