double ff_lpc_calc_ref_coefs_f(LPCContext *s, const float *samples, int len, int order, double *ref) { int i; double signal = 0.0f, avg_err = 0.0f; double autoc[MAX_LPC_ORDER+1] = {0}, error[MAX_LPC_ORDER+1] = {0}; const double a = 0.5f, b = 1.0f - a; /* Apply windowing */ for (i = 0; i < len; i++) { double weight = a - b*cos((2*M_PI*i)/(len - 1)); s->windowed_samples[i] = weight*samples[i]; } s->lpc_compute_autocorr(s->windowed_samples, len, order, autoc); signal = autoc[0]; compute_ref_coefs(autoc, order, ref, error); for (i = 0; i < order; i++) avg_err = (avg_err + error[i])/2.0f; return signal/avg_err; }
double ff_lpc_calc_ref_coefs_f(LPCContext *s, const float *samples, int len, int order, double *ref) { int i; double signal = 0.0f, avg_err = 0.0f; double autoc[MAX_LPC_ORDER+1] = {0}, error[MAX_LPC_ORDER+1] = {0}; const double a = 0.5f, b = 1.0f - a;   for (i = 0; i < len; i++) { double weight = a - b*cos((2*M_PI*i)/(len - 1)); s->windowed_samples[i] = weight*samples[i]; } s->lpc_compute_autocorr(s->windowed_samples, len, order, autoc); signal = autoc[0]; compute_ref_coefs(autoc, order, ref, error); for (i = 0; i < order; i++) avg_err = (avg_err + error[i])/2.0f; return signal/avg_err; }