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;
    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        ffmpeg_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}']