int ff_lpc_calc_coefs(LPCContext *s,
                      const int32_t *samples, int blocksize, int min_order,
                      int max_order, int precision,
                      int32_t coefs[][MAX_LPC_ORDER], int *shift,
                      enum FFLPCType lpc_type, int lpc_passes,
                      int omethod, int max_shift, int zero_shift)
{
    double autoc[MAX_LPC_ORDER+1];
    double ref[MAX_LPC_ORDER];
    double lpc[MAX_LPC_ORDER][MAX_LPC_ORDER];
    int i, j, pass;
    int opt_order;
    av_assert2(max_order >= MIN_LPC_ORDER && max_order <= MAX_LPC_ORDER &&
           lpc_type > FF_LPC_TYPE_FIXED);
    /* reinit LPC context if parameters have changed */
    if (blocksize != s->blocksize || max_order != s->max_order ||
        lpc_type  != s->lpc_type) {
        ff_lpc_end(s);
        ff_lpc_init(s, blocksize, max_order, lpc_type);
    }
    if (lpc_type == FF_LPC_TYPE_LEVINSON) {
        double *windowed_samples = s->windowed_samples + max_order;
        s->lpc_apply_welch_window(samples, blocksize, windowed_samples);
        s->lpc_compute_autocorr(windowed_samples, blocksize, max_order, autoc);
        compute_lpc_coefs(autoc, max_order, &lpc[0][0], MAX_LPC_ORDER, 0, 1);
        for(i=0; i<max_order; i++)
            ref[i] = fabs(lpc[i][i]);
    } else if (lpc_type == FF_LPC_TYPE_CHOLESKY) {
        LLSModel m[2];
        double var[MAX_LPC_ORDER+1], av_uninit(weight);
        for(pass=0; pass<lpc_passes; pass++){
            av_init_lls(&m[pass&1], max_order);
            weight=0;
            for(i=max_order; i<blocksize; i++){
                for(j=0; j<=max_order; j++)
                    var[j]= samples[i-j];
                if(pass){
                    double eval, inv, rinv;
                    eval= av_evaluate_lls(&m[(pass-1)&1], var+1, max_order-1);
                    eval= (512>>pass) + fabs(eval - var[0]);
                    inv = 1/eval;
                    rinv = sqrt(inv);
                    for(j=0; j<=max_order; j++)
                        var[j] *= rinv;
                    weight += inv;
                }else
                    weight++;
                av_update_lls(&m[pass&1], var, 1.0);
            }
            av_solve_lls(&m[pass&1], 0.001, 0);
        }
        for(i=0; i<max_order; i++){
            for(j=0; j<max_order; j++)
                lpc[i][j]=-m[(pass-1)&1].coeff[i][j];
            ref[i]= sqrt(m[(pass-1)&1].variance[i] / weight) * (blocksize - max_order) / 4000;
        }
        for(i=max_order-1; i>0; i--)
            ref[i] = ref[i-1] - ref[i];
    }
    opt_order = max_order;
    if(omethod == ORDER_METHOD_EST) {
        opt_order = estimate_best_order(ref, min_order, max_order);
        i = opt_order-1;
        quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i], max_shift, zero_shift);
    } else {
        for(i=min_order-1; i<max_order; i++) {
            quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i], max_shift, zero_shift);
        }
    }
    return opt_order;
}