AVDictionaryEntry *
av_dict_get(AVDictionary *m, const char *key, const AVDictionaryEntry *prev, int flags)
{
    unsigned int i, j;

    if(!m)
        return NULL;

    if(prev) i= prev - m->elems + 1;
    else     i= 0;

    for(; i<m->count; i++){
        const char *s= m->elems[i].key;
        if(flags & AV_DICT_MATCH_CASE) for(j=0;         s[j]  ==         key[j]  && key[j]; j++);
        else                               for(j=0; toupper(s[j]) == toupper(key[j]) && key[j]; j++);
        if(key[j])
            continue;
        if(s[j] && !(flags & AV_DICT_IGNORE_SUFFIX))
            continue;
        return &m->elems[i];
    }
    return NULL;
}