- return est;
-}
-
-/**
- * Calculate LPC coefficients for multiple orders
- */
-static int lpc_calc_coefs(const int32_t *samples, int blocksize, int max_order,
- int precision, int32_t coefs[][MAX_LPC_ORDER],
- int *shift, int use_lpc, int omethod)
-{
- 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;
-
- assert(max_order >= MIN_LPC_ORDER && max_order <= MAX_LPC_ORDER);
-
- if(use_lpc == 1){
- compute_autocorr(samples, blocksize, max_order+1, autoc);
-
- compute_lpc_coefs(autoc, max_order, lpc, ref);
- }else{
- LLSModel m[2];
- double var[MAX_LPC_ORDER+1], eval, weight;
-
- for(pass=0; pass<use_lpc-1; 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){
- eval= av_evaluate_lls(&m[(pass-1)&1], var+1, max_order-1);
- eval= (512>>pass) + fabs(eval - var[0]);
- for(j=0; j<=max_order; j++)
- var[j]/= sqrt(eval);
- weight += 1/eval;
- }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, max_order);
- i = opt_order-1;
- quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i]);
- } else {
- for(i=0; i<max_order; i++) {
- quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i]);
- }
- }
-
- return opt_order;