static int get_moov_size(AVFormatContext *s)
{
    int ret;
    AVIOContext *moov_buf;
    MOVMuxContext *mov = s->priv_data;

    if ((ret = ffio_open_null_buf(&moov_buf)) < 0)
        return ret;
    if ((ret = mov_write_moov_tag(moov_buf, mov, s)) < 0)
        return ret;
    return ffio_close_null_buf(moov_buf);
}
Unknown