static int decode_nal_sei_pic_timing(HEVCSEIContext *s, GetBitContext *gb, const HEVCParamSets *ps,
                                     void *logctx, int size)
{
    HEVCSEIPictureTiming *h = &s->picture_timing;
    HEVCSPS *sps;

    if (!ps->sps_list[s->active_seq_parameter_set_id])
        return(AVERROR(ENOMEM));
    sps = (HEVCSPS*)ps->sps_list[s->active_seq_parameter_set_id]->data;

    if (sps->vui.frame_field_info_present_flag) {
        int pic_struct = get_bits(gb, 4);
        h->picture_struct = AV_PICTURE_STRUCTURE_UNKNOWN;
        if (pic_struct == 2) {
            av_log(logctx, AV_LOG_DEBUG, "BOTTOM Field\n");
            h->picture_struct = AV_PICTURE_STRUCTURE_BOTTOM_FIELD;
        } else if (pic_struct == 1) {
            av_log(logctx, AV_LOG_DEBUG, "TOP Field\n");
            h->picture_struct = AV_PICTURE_STRUCTURE_TOP_FIELD;
        }
        get_bits(gb, 2);                   // source_scan_type
        get_bits(gb, 1);                   // duplicate_flag
        skip_bits1(gb);
        size--;
    }
    skip_bits_long(gb, 8 * size);

    return 0;
}