ff_init_scantable(s->dsp.idct_permutation, &s->intra_h_scantable, ff_alternate_vertical_scan); ff_init_scantable(s->dsp.idct_permutation, &s->intra_v_scantable, ff_alternate_vertical_scan);
static void mpeg_decode_picture_coding_extension(MpegEncContext *s){    s->full_pel[0] = s->full_pel[1] = 0;    s->mpeg_f_code[0][0] = get_bits(&s->gb, 4);    s->mpeg_f_code[0][1] = get_bits(&s->gb, 4);    s->mpeg_f_code[1][0] = get_bits(&s->gb, 4);    s->mpeg_f_code[1][1] = get_bits(&s->gb, 4);    s->intra_dc_precision = get_bits(&s->gb, 2);    s->picture_structure = get_bits(&s->gb, 2);    s->top_field_first = get_bits1(&s->gb);    s->frame_pred_frame_dct = get_bits1(&s->gb);    s->concealment_motion_vectors = get_bits1(&s->gb);    s->q_scale_type = get_bits1(&s->gb);    s->intra_vlc_format = get_bits1(&s->gb);    s->alternate_scan = get_bits1(&s->gb);    s->repeat_first_field = get_bits1(&s->gb);    s->chroma_420_type = get_bits1(&s->gb);    s->progressive_frame = get_bits1(&s->gb);        if(s->picture_structure == PICT_FRAME)        s->first_field=0;    else{        s->first_field ^= 1;        memset(s->mbskip_table, 0, s->mb_stride*s->mb_height);    }        if(s->alternate_scan){        ff_init_scantable(s->dsp.idct_permutation, &s->inter_scantable  , ff_alternate_vertical_scan);        ff_init_scantable(s->dsp.idct_permutation, &s->intra_scantable  , ff_alternate_vertical_scan);        ff_init_scantable(s->dsp.idct_permutation, &s->intra_h_scantable, ff_alternate_vertical_scan);        ff_init_scantable(s->dsp.idct_permutation, &s->intra_v_scantable, ff_alternate_vertical_scan);    }else{        ff_init_scantable(s->dsp.idct_permutation, &s->inter_scantable  , ff_zigzag_direct);        ff_init_scantable(s->dsp.idct_permutation, &s->intra_scantable  , ff_zigzag_direct);        ff_init_scantable(s->dsp.idct_permutation, &s->intra_h_scantable, ff_alternate_horizontal_scan);        ff_init_scantable(s->dsp.idct_permutation, &s->intra_v_scantable, ff_alternate_vertical_scan);    }        /* composite display not parsed */    dprintf("intra_dc_precision=%d\n", s->intra_dc_precision);    dprintf("picture_structure=%d\n", s->picture_structure);    dprintf("top field first=%d\n", s->top_field_first);    dprintf("repeat first field=%d\n", s->repeat_first_field);    dprintf("conceal=%d\n", s->concealment_motion_vectors);    dprintf("intra_vlc_format=%d\n", s->intra_vlc_format);    dprintf("alternate_scan=%d\n", s->alternate_scan);    dprintf("frame_pred_frame_dct=%d\n", s->frame_pred_frame_dct);    dprintf("progressive_frame=%d\n", s->progressive_frame);}