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/* shepard-risset.c
* generate indefinitely rising/descending tones sequence/amplitude
* to feed to tones program.
*
* Usage: shepard-risset mid-freq partials density shifts [db]
*
* mid-freq specifies the middle freq.
* partials is the number of seperate frequencies in the mixture
* density ratio between partials
* shifts is the number of freq shifts to create
* [db] optional attenuation in dB at the edges
*
* Problems...........
* with the dB values going positive and oscillating.
* Initial values are correct - it's the amendment for successive shifts
*
* also need to loop a total of partial blocks of shifts specs!
*/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define MAXSHIFTS 100
#define MAXPARTIALS 50
#define DEFDB -40.0
double midfreq,density,minf,maxf;
int partials,shifts;
help(e)
int e;
{
puts("\
Usage: shepard-risset mid-freq partials density shifts [-db]\n\
\n\
generate indefinitely rising/descending tones sequence/amplitude\n\
to feed to tones program.\n\
\n\
mid-freq specifies the middle freq.\n\
partials is the number of seperate frequencies in the mixture\n\
density ratio between partials\n\
shifts is the number of freq shifts to create\
");
printf("-db optional - number of db down at limits, default %.2fdb\n",DEFDB);
printf("\nmid-freq must be >= 100Hz, partials >=3 and < %d,\n shifts >=3 and < %d, and density>0\n",
MAXPARTIALS, MAXSHIFTS);
return(0);
}
main(argc,argv)
int argc;
char **argv;
{
int i,j,k,l,m,n,N;
double x,y,z,f,sr;
double db,dbi,Dbs[MAXPARTIALS*MAXSHIFTS];
int freqs[MAXPARTIALS*MAXSHIFTS];
argv++; argc--;
if (argc!=4 && argc!=5) exit(help(1));
midfreq=strtod(argv[0],NULL);
partials=atoi(argv[1]);
density=strtod(argv[2],NULL);
shifts=atoi(argv[3]);
db=DEFDB;
if (argc==5) db=strtod(argv[4],NULL);
printf("echo midfreq=%.3fHz number of partials is %d\n",midfreq,partials);
printf("echo density=%.3f number of frequency shifts=%d\n",density,shifts);
if (midfreq<100.0 || partials<3 || partials>MAXPARTIALS
|| shifts<3 || shifts>MAXSHIFTS || density<=0) {
printf("mid freq must be >= 100Hz, partials >=3 and < %d,\n shifts >=3 and < %d, and density > 0",
MAXPARTIALS, MAXSHIFTS);
exit(1);
}
maxf=midfreq*pow(density,((double)partials)/2.0);
minf=midfreq/pow(density,((double)partials)/2.0);
printf("echo Freq range is %.3fHz - %.3fHz a bandwidth of %.3fHz\n",
minf,maxf,maxf-minf);
N=shifts*partials;
sr=pow(density,1/(double)shifts); /* ratio for freq increase for each shift */
if (db>0) db=-db;
dbi=(2.0*-db)/(double)(N);
for (i=0,x=db,f=minf; i<N; i++, x+=dbi, f*=sr) {
Dbs[i]=(x<0)?x:-x;
freqs[i]=(int)rint(f);
}
for (i=0; i<N; i++) {
for ( l=i, j=0; j<partials; j++, l=(l+shifts)%N) {
printf("%s%d@%.2f",(j)?",":"",freqs[l],Dbs[l]);
}
puts("");
}
exit(0);
for (i=0, f=minf; i<shifts; i++, f*=sr) {
z=(dbi*i)/shifts;
for (j=0, x=f; j<partials; j++, x*=density) {
y=Dbs[j]+z;
printf("%s%d@%.2f",(j)?",":"",(int)rint(x),(y<0)?y:-y);
}
puts("");
}
}
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