ffmpeg.c:2613: error: Null Dereference
  pointer `mid` last assigned on line 2613 could be null and is dereferenced at line 2613, column 5.

ffmpeg.c:2605:1: start of procedure opt_metadata()
2603. }
2604. 
2605. static int opt_metadata(const char *opt, const char *arg)
      ^
2606. {
2607.     char *mid= strchr(arg, '=');

ffmpeg.c:2607:5: 
2605. static int opt_metadata(const char *opt, const char *arg)
2606. {
2607.     char *mid= strchr(arg, '=');
          ^
2608. 
2609.     if(!mid){

ffmpeg.c:2609:9: Taking true branch
2607.     char *mid= strchr(arg, '=');
2608. 
2609.     if(!mid){
              ^
2610.         fprintf(stderr, "Missing =\n");
2611.         av_exit(1);

ffmpeg.c:2610:9: 
2608. 
2609.     if(!mid){
2610.         fprintf(stderr, "Missing =\n");
              ^
2611.         av_exit(1);
2612.     }

ffmpeg.c:2611:9: Skipping av_exit(): empty list of specs
2609.     if(!mid){
2610.         fprintf(stderr, "Missing =\n");
2611.         av_exit(1);
              ^
2612.     }
2613.     *mid++= 0;

ffmpeg.c:2613:5: 
2611.         av_exit(1);
2612.     }
2613.     *mid++= 0;
          ^
2614. 
2615.     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}']