static int tb_unreliable(AVCodecContext *c)
{
    if (c->time_base.den >= 101L * c->time_base.num ||
        c->time_base.den <    5L * c->time_base.num ||
        // c->codec_tag == AV_RL32("DIVX") ||
        // c->codec_tag == AV_RL32("XVID") ||
        c->codec_id == AV_CODEC_ID_MPEG2VIDEO ||
        c->codec_id == AV_CODEC_ID_H264)
        return 1;
    return 0;
}