static int mov_write_mfra_tag(AVIOContext *pb, MOVMuxContext *mov)
{
    int64_t pos = avio_tell(pb);
    int i;

    avio_wb32(pb, 0); /* size placeholder */
    ffio_wfourcc(pb, "mfra");
    /* An empty mfra atom is enough to indicate to the publishing point that
     * the stream has ended. */
    if (mov->flags & FF_MOV_FLAG_ISML)
        return update_size(pb, pos);

    for (i = 0; i < mov->nb_streams; i++) {
        MOVTrack *track = &mov->tracks[i];
        if (track->nb_frag_info)
            mov_write_tfra_tag(pb, track);
    }

    avio_wb32(pb, 16);
    ffio_wfourcc(pb, "mfro");
    avio_wb32(pb, 0); /* version + flags */
    avio_wb32(pb, avio_tell(pb) + 4 - pos);

    return update_size(pb, pos);
}

The product divides a value by zero.