#include "libavutil/common.h"
#include "libavutil/mathematics.h"
#include "fft.h"
+#include "fft-internal.h"
/**
* @file
* MDCT/IMDCT transforms.
*/
-// Generate a Kaiser-Bessel Derived Window.
-#define BESSEL_I0_ITER 50 // default: 50 iterations of Bessel I0 approximation
-av_cold void ff_kbd_window_init(float *window, float alpha, int n)
-{
- int i, j;
- double sum = 0.0, bessel, tmp;
- double local_window[FF_KBD_WINDOW_MAX];
- double alpha2 = (alpha * M_PI / n) * (alpha * M_PI / n);
-
- assert(n <= FF_KBD_WINDOW_MAX);
-
- for (i = 0; i < n; i++) {
- tmp = i * (n - i) * alpha2;
- bessel = 1.0;
- for (j = BESSEL_I0_ITER; j > 0; j--)
- bessel = bessel * tmp / (j * j) + 1;
- sum += bessel;
- local_window[i] = sum;
- }
-
- sum++;
- for (i = 0; i < n; i++)
- window[i] = sqrt(local_window[i] / sum);
-}
-
-#include "mdct_tablegen.h"
+#if CONFIG_FFT_FLOAT
+# define RSCALE(x) (x)
+#else
+# define RSCALE(x) ((x) >> 1)
+#endif
/**
* init MDCT or IMDCT computation.
scale = sqrt(fabs(scale));
for(i=0;i<n4;i++) {
alpha = 2 * M_PI * (i + theta) / n;
- s->tcos[i*tstep] = -cos(alpha) * scale;
- s->tsin[i*tstep] = -sin(alpha) * scale;
+ s->tcos[i*tstep] = FIX15(-cos(alpha) * scale);
+ s->tsin[i*tstep] = FIX15(-sin(alpha) * scale);
}
return 0;
fail:
return -1;
}
-/* complex multiplication: p = a * b */
-#define CMUL(pre, pim, are, aim, bre, bim) \
-{\
- FFTSample _are = (are);\
- FFTSample _aim = (aim);\
- FFTSample _bre = (bre);\
- FFTSample _bim = (bim);\
- (pre) = _are * _bre - _aim * _bim;\
- (pim) = _are * _bim + _aim * _bre;\
-}
-
/**
* Compute the middle half of the inverse MDCT of size N = 2^nbits,
* thus excluding the parts that can be derived by symmetry
void ff_mdct_calc_c(FFTContext *s, FFTSample *out, const FFTSample *input)
{
int i, j, n, n8, n4, n2, n3;
- FFTSample re, im;
+ FFTDouble re, im;
const uint16_t *revtab = s->revtab;
const FFTSample *tcos = s->tcos;
const FFTSample *tsin = s->tsin;
/* pre rotation */
for(i=0;i<n8;i++) {
- re = -input[2*i+n3] - input[n3-1-2*i];
- im = -input[n4+2*i] + input[n4-1-2*i];
+ re = RSCALE(-input[2*i+n3] - input[n3-1-2*i]);
+ im = RSCALE(-input[n4+2*i] + input[n4-1-2*i]);
j = revtab[i];
CMUL(x[j].re, x[j].im, re, im, -tcos[i], tsin[i]);
- re = input[2*i] - input[n2-1-2*i];
- im = -(input[n2+2*i] + input[n-1-2*i]);
+ re = RSCALE( input[2*i] - input[n2-1-2*i]);
+ im = RSCALE(-input[n2+2*i] - input[ n-1-2*i]);
j = revtab[n8 + i];
CMUL(x[j].re, x[j].im, re, im, -tcos[n8 + i], tsin[n8 + i]);
}