static void init_dequantizer(Vp3DecodeContext *s, int qpi)
{
    int ac_scale_factor = s->coded_ac_scale_factor[s->qps[qpi]];
    int dc_scale_factor = s->coded_dc_scale_factor[s->qps[qpi]];
    int i, plane, inter, qri, bmi, bmj, qistart;

    for(inter=0; inter<2; inter++){
        for(plane=0; plane<3; plane++){
            int sum=0;
            for(qri=0; qri<s->qr_count[inter][plane]; qri++){
                sum+= s->qr_size[inter][plane][qri];
                if(s->qps[qpi] <= sum)
                    break;
            }
            qistart= sum - s->qr_size[inter][plane][qri];
            bmi= s->qr_base[inter][plane][qri  ];
            bmj= s->qr_base[inter][plane][qri+1];
            for(i=0; i<64; i++){
                int coeff= (  2*(sum    -s->qps[qpi])*s->base_matrix[bmi][i]
                            - 2*(qistart-s->qps[qpi])*s->base_matrix[bmj][i]
                            + s->qr_size[inter][plane][qri])
                           / (2*s->qr_size[inter][plane][qri]);

                int qmin= 8<<(inter + !i);
                int qscale= i ? ac_scale_factor : dc_scale_factor;

                s->qmat[qpi][inter][plane][s->dsp.idct_permutation[i]]= av_clip((qscale * coeff)/100 * 4, qmin, 4096);
            }
            // all DC coefficients use the same quant so as not to interfere with DC prediction
            s->qmat[qpi][inter][plane][0] = s->qmat[0][inter][plane][0];
        }
    }

    memset(s->qscale_table, (FFMAX(s->qmat[0][0][0][1], s->qmat[0][0][1][1])+8)/16, 512); //FIXME finetune
}