s->modified_quant=1; s->loop_filter=1;
static int rv20_decode_picture_header(MpegEncContext *s){    int seq, mb_pos, i;    i= get_bits(&s->gb, 2);    switch(i){    case 0: s->pict_type= I_TYPE; break;    case 1: s->pict_type= I_TYPE; break; //hmm ...    case 2: s->pict_type= P_TYPE; break;    case 3: s->pict_type= B_TYPE; break;    default:         av_log(s->avctx, AV_LOG_ERROR, "unknown frame type\n");        return -1;    }        if (get_bits(&s->gb, 1)){        av_log(s->avctx, AV_LOG_ERROR, "unknown bit set\n");        return -1;    }    s->qscale = get_bits(&s->gb, 5);    if(s->qscale==0){        av_log(s->avctx, AV_LOG_ERROR, "error, qscale:0\n");        return -1;    }    if(s->avctx->sub_id == 0x20200002)        seq= get_bits(&s->gb, 16);    else        seq= get_bits(&s->gb, 8);    for(i=0; i<6; i++){        if(s->mb_width*s->mb_height < ff_mba_max[i]) break;    }    mb_pos= get_bits(&s->gb, ff_mba_length[i]);    s->mb_x= mb_pos % s->mb_width;    s->mb_y= mb_pos / s->mb_width;    s->no_rounding= get_bits1(&s->gb);        s->f_code = 1;    s->unrestricted_mv = 1;    s->h263_aic= s->pict_type == I_TYPE;//    s->alt_inter_vlc=1;//    s->obmc=1;//    s->umvplus=1;//    s->modified_quant=1;        if(s->avctx->debug & FF_DEBUG_PICT_INFO){            av_log(s->avctx, AV_LOG_INFO, "num:%5d x:%2d y:%2d type:%d qscale:%2d rnd:%d\n",                    seq, s->mb_x, s->mb_y, s->pict_type, s->qscale, s->no_rounding);    }    if (s->pict_type == B_TYPE){        av_log(s->avctx, AV_LOG_ERROR, "b frame not supported\n");        return -1;    }    return s->mb_width*s->mb_height - mb_pos;}