s->pict_type=I_TYPE;
static void common_init(MpegEncContext *s){int i;    s->y_dc_scale_table=    s->c_dc_scale_table= ff_mpeg1_dc_scale_table;    if(!s->encoding)        for(i=0;i<64;i++)       s->dsp.idct_permutation[i]=i;}