static int decode_pic_timing(HEVCContext *s)
{
    GetBitContext *gb = &s->HEVClc->gb;
    HEVCSPS *sps = (HEVCSPS*)s->sps_list[s->active_seq_parameter_set_id]->data;

    if (!sps)
        return(AVERROR(ENOMEM));

    if (sps->vui.frame_field_info_present_flag) {
        int pic_struct = get_bits(gb, 4);
        s->picture_struct = AV_PICTURE_STRUCTURE_UNKNOWN;
        if (pic_struct == 2) {
            av_log(s->avctx, AV_LOG_DEBUG, "BOTTOM Field\n");
            s->picture_struct = AV_PICTURE_STRUCTURE_BOTTOM_FIELD;
        } else if (pic_struct == 1) {
            av_log(s->avctx, AV_LOG_DEBUG, "TOP Field\n");
            s->picture_struct = AV_PICTURE_STRUCTURE_TOP_FIELD;
        }
        get_bits(gb, 2);                   // source_scan_type
        get_bits(gb, 1);                   // duplicate_flag
    }
    return 1;
}