static int mov_preroll_write_stbl_atoms(AVIOContext *pb, MOVTrack *track)
{
    struct sgpd_entry {
        int count;
        int16_t roll_distance;
        int group_description_index;
    };

    struct sgpd_entry *sgpd_entries = NULL;
    int entries = -1;
    int group = 0;
    int i, j;

    const int OPUS_SEEK_PREROLL_MS = 80;
    int roll_samples = av_rescale_q(OPUS_SEEK_PREROLL_MS,
                                    (AVRational){1, 1000},
                                    (AVRational){1, 48000});

    if (!track->entry)
        return 0;

    sgpd_entries = av_malloc_array(track->entry, sizeof(*sgpd_entries));
    if (!sgpd_entries)
        return AVERROR(ENOMEM);

    av_assert0(track->par->codec_id == AV_CODEC_ID_OPUS || track->par->codec_id == AV_CODEC_ID_AAC);

    if (track->par->codec_id == AV_CODEC_ID_OPUS) {
        for (i = 0; i < track->entry; i++) {
            int roll_samples_remaining = roll_samples;
            int distance = 0;
            for (j = i - 1; j >= 0; j--) {
                roll_samples_remaining -= get_cluster_duration(track, j);
                distance++;
                if (roll_samples_remaining <= 0)
                    break;
            }
            /* We don't have enough preceeding samples to compute a valid
               roll_distance here, so this sample can't be independently
               decoded. */
            if (roll_samples_remaining > 0)
                distance = 0;
            /* Verify distance is a minimum of 2 (60ms) packets and a maximum of
               32 (2.5ms) packets. */
            av_assert0(distance == 0 || (distance >= 2 && distance <= 32));
            if (i && distance == sgpd_entries[entries].roll_distance) {
                sgpd_entries[entries].count++;
            } else {
                entries++;
                sgpd_entries[entries].count = 1;
                sgpd_entries[entries].roll_distance = distance;
                sgpd_entries[entries].group_description_index = distance ? ++group : 0;
            }
        }
    } else {
        entries++;
        sgpd_entries[entries].count = track->sample_count;
        sgpd_entries[entries].roll_distance = 1;
        sgpd_entries[entries].group_description_index = ++group;
    }
    entries++;

    if (!group) {
        av_free(sgpd_entries);
        return 0;
    }

    /* Write sgpd tag */
    avio_wb32(pb, 24 + (group * 2)); /* size */
    ffio_wfourcc(pb, "sgpd");
    avio_wb32(pb, 1 << 24); /* fullbox */
    ffio_wfourcc(pb, "roll");
    avio_wb32(pb, 2); /* default_length */
    avio_wb32(pb, group); /* entry_count */
    for (i = 0; i < entries; i++) {
        if (sgpd_entries[i].group_description_index) {
            avio_wb16(pb, -sgpd_entries[i].roll_distance); /* roll_distance */
        }
    }

    /* Write sbgp tag */
    avio_wb32(pb, 20 + (entries * 8)); /* size */
    ffio_wfourcc(pb, "sbgp");
    avio_wb32(pb, 0); /* fullbox */
    ffio_wfourcc(pb, "roll");
    avio_wb32(pb, entries); /* entry_count */
    for (i = 0; i < entries; i++) {
        avio_wb32(pb, sgpd_entries[i].count); /* sample_count */
        avio_wb32(pb, sgpd_entries[i].group_description_index); /* group_description_index */
    }

    av_free(sgpd_entries);
    return 0;
}

The product divides a value by zero.