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Eliminate use of complex.h from iirfilter.c 

Originally committed as revision 19396 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Alex Converse 2009-07-10 20:45:13 +00:00
parent 291fd18a6e
commit e187d87d7d
1 changed files with 27 additions and 12 deletions
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39
libavcodec/iirfilter.c
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@ -25,7 +25,6 @@
*/
#include "iirfilter.h"
#include <complex.h>
#include <math.h>
/**
@ -56,7 +55,7 @@ struct FFIIRFilterCoeffs* ff_iir_filter_init_coeffs(enum IIRFilterType filt_type
int i, j, size;
FFIIRFilterCoeffs *c;
double wa;
double complex p[MAXORDER + 1];
double p[MAXORDER + 1][2];
if(filt_type != FF_FILTER_TYPE_BUTTERWORTH || filt_mode != FF_FILTER_MODE_LOWPASS)
return NULL;
@ -74,23 +73,39 @@ struct FFIIRFilterCoeffs* ff_iir_filter_init_coeffs(enum IIRFilterType filt_type
for(i = 1; i < (order >> 1) + 1; i++)
c->cx[i] = c->cx[i - 1] * (order - i + 1LL) / i;
p[0] = 1.0;
p[0][0] = 1.0;
p[0][1] = 0.0;
for(i = 1; i <= order; i++)
p[i] = 0.0;
p[i][0] = p[i][1] = 0.0;
for(i = 0; i < order; i++){
double complex zp;
double zp[2];
double th = (i + (order >> 1) + 0.5) * M_PI / order;
zp = cexp(I*th) * wa;
zp = (zp + 2.0) / (zp - 2.0);
double a_re, a_im, c_re, c_im;
zp[0] = cos(th) * wa;
zp[1] = sin(th) * wa;
a_re = zp[0] + 2.0;
c_re = zp[0] - 2.0;
a_im =
c_im = zp[1];
zp[0] = (a_re * c_re + a_im * c_im) / (c_re * c_re + c_im * c_im);
zp[1] = (a_im * c_re - a_re * c_im) / (c_re * c_re + c_im * c_im);
for(j = order; j >= 1; j--)
p[j] = zp*p[j] + p[j - 1];
p[0] *= zp;
{
a_re = p[j][0];
a_im = p[j][1];
p[j][0] = a_re*zp[0] - a_im*zp[1] + p[j-1][0];
p[j][1] = a_re*zp[1] + a_im*zp[0] + p[j-1][1];
}
a_re = p[0][0]*zp[0] - p[0][1]*zp[1];
p[0][1] = p[0][0]*zp[1] + p[0][1]*zp[0];
p[0][0] = a_re;
}
c->gain = creal(p[order]);
c->gain = p[order][0];
for(i = 0; i < order; i++){
c->gain += creal(p[i]);
c->cy[i] = creal(-p[i] / p[order]);
c->gain += p[i][0];
c->cy[i] = (-p[i][0] * p[order][0] + -p[i][1] * p[order][1]) /
(p[order][0] * p[order][0] + p[order][1] * p[order][1]);
}
c->gain /= 1 << order;