void ff_id3v2_free_extra_meta(ID3v2ExtraMeta **extra_meta)
{
    ID3v2ExtraMeta *current = *extra_meta, *next;
    const ID3v2EMFunc *extra_func;

    while (current) {
        if ((extra_func = get_extra_meta_func(current->tag, 1)))
            extra_func->free(current->data);
        next = current->next;
        av_freep(&current);
        current = next;
    }
}