s->chroma_qscale= s->chroma_qscale_table[s->qscale];
static int h263_decode_gob_header(MpegEncContext *s){    unsigned int val, gfid;    int left;        /* Check for GOB Start Code */    val = show_bits(&s->gb, 16);    if(val)        return -1;        /* We have a GBSC probably with GSTUFF */    skip_bits(&s->gb, 16); /* Drop the zeros */    left= s->gb.size_in_bits - get_bits_count(&s->gb);    //MN: we must check the bits left or we might end in a infinite loop (or segfault)    for(;left>13; left--){        if(get_bits1(&s->gb)) break; /* Seek the '1' bit */    }    if(left<=13)         return -1;#ifdef DEBUG    fprintf(stderr,"\nGOB Start Code at MB %d\n", (s->mb_y * s->mb_width) + s->mb_x);#endif    s->gob_number = get_bits(&s->gb, 5); /* GN */    gfid = get_bits(&s->gb, 2); /* GFID */    s->qscale = get_bits(&s->gb, 5); /* GQUANT */    if(s->qscale==0)         return -1;    s->mb_x= 0;    s->mb_y= s->gob_index* s->gob_number;    if(s->mb_y >= s->mb_height)         return -1;#ifdef DEBUG    fprintf(stderr, "\nGN: %u GFID: %u Quant: %u\n", s->gob_number, gfid, s->qscale);#endif    return 0;}