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#include "pv.h"
#include "math.h"
/*
* make balanced pair of analysis (A) and synthesis (S) windows;
* window lengths are Nw, FFT length is N, synthesis interpolation
* factor is I, and osc is true (1) if oscillator bank resynthesis
* is specified
*/
void makewindows( float *H, float *A, float *S, int Nw, int N, int I, int osc )
{
int i ;
float sum ;
/*
* basic Hamming windows
*/
for ( i = 0 ; i < Nw ; i++ )
H[i] = A[i] = S[i] = 0.54 - 0.46*cos( PV_2PI*i/(Nw - 1) ) ;
/*
* when Nw > N, also apply interpolating (sinc) windows to
* ensure that window are 0 at increments of N (the FFT length)
* away from the center of the analysis window and of I away
* from the center of the synthesis window
*/
if ( Nw > N ) {
float x ;
/*
* take care to create symmetrical windows
*/
x = -(Nw - 1)/2. ;
for ( i = 0 ; i < Nw ; i++, x += 1. )
if ( x != 0. ) {
A[i] *= N*sin( PV_PI*x/N )/(PV_PI*x) ;
if ( I )
S[i] *= I*sin( PV_PI*x/I )/(PV_PI*x) ;
}
}
/*
* normalize windows for unity gain across unmodified
* analysis-synthesis procedure
*/
for ( sum = i = 0 ; i < Nw ; i++ )
sum += A[i] ;
for ( i = 0 ; i < Nw ; i++ ) {
float afac = 2./sum ;
float sfac = Nw > N ? 1./afac : afac ;
A[i] *= afac ;
S[i] *= sfac ;
}
if ( Nw <= N && I ) {
for ( sum = i = 0 ; i < Nw ; i += I )
sum += S[i]*S[i] ;
for ( sum = 1./sum, i = 0 ; i < Nw ; i++ )
S[i] *= sum ;
}
}
void makehamming( float *H, float *A, float *S, int Nw, int N, int I, int osc,int odd )
{
int i;
float sum ;
/*
* basic Hamming windows
*/
if (odd) {
for ( i = 0 ; i < Nw ; i++ )
H[i] = A[i] = S[i] = sqrt(0.54 - 0.46*cos( PV_2PI*i/(Nw - 1) ));
}
else {
for ( i = 0 ; i < Nw ; i++ )
H[i] = A[i] = S[i] = 0.54 - 0.46*cos( PV_2PI*i/(Nw - 1) );
}
/*
* when Nw > N, also apply interpolating (sinc) windows to
* ensure that window are 0 at increments of N (the FFT length)
* away from the center of the analysis window and of I away
* from the center of the synthesis window
*/
if ( Nw > N ) {
float x ;
/*
* take care to create symmetrical windows
*/
x = -(Nw - 1)/2. ;
for ( i = 0 ; i < Nw ; i++, x += 1. )
if ( x != 0. ) {
A[i] *= N*sin( PV_PI*x/N )/(PV_PI*x) ;
if ( I )
S[i] *= I*sin( PV_PI*x/I )/(PV_PI*x) ;
}
}
/*
* normalize windows for unity gain across unmodified
* analysis-synthesis procedure
*/
for ( sum = i = 0 ; i < Nw ; i++ )
sum += A[i] ;
for ( i = 0 ; i < Nw ; i++ ) {
float afac = 2./sum ;
float sfac = Nw > N ? 1./afac : afac ;
A[i] *= afac ;
S[i] *= sfac ;
}
if ( Nw <= N && I ) {
for ( sum = i = 0 ; i < Nw ; i += I )
sum += S[i]*S[i] ;
for ( sum = 1./sum, i = 0 ; i < Nw ; i++ )
S[i] *= sum ;
}
}
void makehanning( float *H, float *A, float *S, int Nw, int N, int I, int osc, int odd )
{
int i;
float sum ;
/*
* basic Hanning windows
*/
if (odd) {
for ( i = 0 ; i < Nw ; i++ )
H[i] = A[i] = S[i] = sqrt(0.5 * (1. + cos(PV_PI + PV_2PI * i / (Nw - 1))));
}
else {
for ( i = 0 ; i < Nw ; i++ )
H[i] = A[i] = S[i] = 0.5 * (1. + cos(PV_PI + PV_2PI * i / (Nw - 1)));
}
/*
* when Nw > N, also apply interpolating (sinc) windows to
* ensure that window are 0 at increments of N (the FFT length)
* away from the center of the analysis window and of I away
* from the center of the synthesis window
*/
if ( Nw > N ) {
float x ;
/*
* take care to create symmetrical windows
*/
x = -(Nw - 1)/2. ;
for ( i = 0 ; i < Nw ; i++, x += 1. )
if ( x != 0. ) {
A[i] *= N*sin( PV_PI*x/N )/(PV_PI*x) ;
if ( I )
S[i] *= I*sin( PV_PI*x/I )/(PV_PI*x) ;
}
}
/*
* normalize windows for unity gain across unmodified
* analysis-synthesis procedure
*/
for ( sum = i = 0 ; i < Nw ; i++ )
sum += A[i] ;
for ( i = 0 ; i < Nw ; i++ ) {
float afac = 2./sum ;
float sfac = Nw > N ? 1./afac : afac ;
A[i] *= afac ;
S[i] *= sfac ;
}
if ( Nw <= N && I ) {
for ( sum = i = 0 ; i < Nw ; i += I )
sum += S[i]*S[i] ;
for ( sum = 1./sum, i = 0 ; i < Nw ; i++ )
S[i] *= sum ;
}
}
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