void lsx_set_dft_filter(dft_filter_t *f, double *h, int n, int post_peak)
{
int i;
f->num_taps = n;
f->post_peak = post_peak;
f->dft_length = lsx_set_dft_length(f->num_taps);
f->coefs = lsx_calloc(f->dft_length, sizeof(*f->coefs));
for (i = 0; i < f->num_taps; ++i)
f->coefs[(i + f->dft_length - f->num_taps + 1) & (f->dft_length - 1)] = h[i] / f->dft_length * 2;
lsx_safe_rdft(f->dft_length, 1, f->coefs);
free(h);
}
static void init_dft_filter(rate_shared_t * p, unsigned which, int num_taps,
sox_sample_t const h[], double Fp, double Fc, double Fn, double att,
int multiplier, double phase, sox_bool allow_aliasing)
{
dft_filter_t * f = &p->half_band[which];
int dft_length, i;
if (f->num_taps)
return;
if (h) { // for half_fir_coefs_low
dft_length = lsx_set_dft_length(num_taps);
f->coefs = lsx_aligned_calloc(dft_length, sizeof(*f->coefs));
for (i = 0; i < num_taps; ++i)
f->coefs[(i + dft_length - num_taps + 1) & (dft_length - 1)]
= h[abs(num_taps / 2 - i)] / dft_length * 2 * multiplier;
f->post_peak = num_taps / 2;
}
else {
double * h2 = lsx_design_lpf(Fp, Fc, Fn, allow_aliasing, att, &num_taps, 0, -1.);
if (phase != 50)
lsx_fir_to_phase(&h2, &num_taps, &f->post_peak, phase);
else f->post_peak = num_taps / 2;
dft_length = lsx_set_dft_length(num_taps);
f->coefs = lsx_aligned_calloc(dft_length, sizeof(*f->coefs));
for (i = 0; i < num_taps; ++i)
f->coefs[(i + dft_length - num_taps + 1) & (dft_length - 1)]
= h2[i] / dft_length * 2 * multiplier;
lsx_free(h2);
}
assert(num_taps & 1);
f->num_taps = num_taps;
f->dft_length = dft_length;
f->tmp_buf = lsx_aligned_malloc(dft_length*sizeof(FFTComplex)/2);
ff_rdft_x(dft_length, 1, f->coefs, f->tmp_buf);
}