/*??
?*?July?5?1991??
?*?Copyright?1991?Lance?Norskog?And?Sundry?Contributors??
?*?This?source?code?is?freely?redistributable?and?may?be?used?for??
?*?any?purpose.??This?copyright?notice?must?be?maintained.???
?*?Lance?Norskog?And?Sundry?Contributors?are?not?responsible?for???
?*?the?consequences?of?using?this?software.??
?*/???
???
/*??
?*?Sound?Tools?Bandpass?effect?file.??
?*??
?*?Algorithm:??2nd?order?recursive?filter.??
?*?Formula?stolen?from?MUSIC56K?a?toolkit?of?56000?assembler?stuff.??
?*?Quote:??
?*???This?is?a?2nd?order?recursive?band?pass?filter?of?the?form.??????????????????
?*???y（n）=?a?*?x（n）?-?b?*?y（n-1）?-?c?*?y（n-2）?????
?*???where?:??????
?*????????x（n）?=?“IN“?????????????
?*????????“OUT“?=?y（n）????????????
?*????????c?=?EXP（-2*pi*cBW/S_RATE）???????????????
?*????????b?=?-4*c/（1+c）*COS（2*pi*cCF/S_RATE）?????
?*???if?cSCL=2?（i.e.?noise?input）?????????????????
?*????????a?=?SQT（（（1+c）*（1+c）-b*b）*（1-c）/（1+c））??????????????????
?*???else?????????
?*????????a?=?SQT（1-b*b/（4*c））*（1-c）??????????????
?*???endif????????
?*???note?:?????cCF?is?the?center?frequency?in?Hertz??????????????
?*????????cBW?is?the?band?width?in?Hertz??????????
?*????????cSCL?is?a?scale?factor?use?1?for?pitched?sounds????????
?*???use?2?for?noise.?????????????
?*??
?*??
?*?July?1?1999?-?Jan?Paul?Schmidt???
?*??
?*???This?looks?like?the?resonator?band?pass?in?SPKit.?It‘s?a??
?*???second?order?all-pole?（IIR）?band-pass?filter?described??
?*???at?the?pages?186?-?189?in??
?*?????Dodge?Charles?&?Jerse?Thomas?A.?1985:???
?*???????Computer?Music?--?Synthesis?Composition?and?Performance.??
?*???????New?York:?Schirmer?Books.????
?*???Reference?from?the?SPKit?manual.??
?*/???
???
#include????
#include????
#include?“st_i.h“???
???
/*?Private?data?for?Bandpass?effect?*/???
typedef?struct?bandstuff?{???
????float???center;???
????float???width;???
????double??A?B?C;???
????double??out1?out2;???
????short???noise;???
????/*?50?bytes?of?data?52?bytes?long?for?allocation?purposes.?*/???
}?*band_t;???
???
/*??
?*?Process?options??
?*/???
int?st_band_getopts（eff_t?effp?int?n?char?**argv）????
{???
????band_t?band?=?（band_t）?effp->priv;???
???
????band->noise?=?0;???
????if?（n?>?0?&&?!strcmp（argv[0]?“-n“））?{???
????????band->noise?=?1;???
????????n--;???
????????argv++;???
????}???
????if?（（n?center））???
????{???
????????st_fail（“Usage:?band?[?-n?]?center?[?width?]“）;???
????????return?（ST_EOF）;???
????}???
????band->width?=?band->center?/?2;???
????if?（（n?>=?2）?&&?!sscanf（argv[1]?“%f“?&band->width））???
????{???
????????st_fail（“Usage:?band?[?-n?]?center?[?width?]“）;???
????????return?（ST_EOF）;???
????}???
????return?（ST_SUCCESS）;???
}???
???
/*??
?*?Prepare?processing.??
?*/???
int?st_band_start（eff_t?effp）???
{???
????band_t?band?=?（band_t）?effp->priv;???
????if?（band->center?>?effp->ininfo.rate/2）???
??

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----

?????文件???????4603??2013-05-03?15:18??數字濾波器的C語言實現，包括高通、低通、帶通濾波器\band.c

?????文件???????2515??2013-05-03?15:18??數字濾波器的C語言實現，包括高通、低通、帶通濾波器\bandpass.c

?????文件???????2957??2013-05-03?15:17??數字濾波器的C語言實現，包括高通、低通、帶通濾波器\btrworth.c

?????文件???????1697??2013-05-03?15:17??數字濾波器的C語言實現，包括高通、低通、帶通濾波器\btrworth.h

?????文件???????9579??2013-05-03?15:16??數字濾波器的C語言實現，包括高通、低通、帶通濾波器\filter.c

?????文件???????3093??2013-05-03?15:15??數字濾波器的C語言實現，包括高通、低通、帶通濾波器\highp.c

?????文件???????2402??2013-05-03?15:14??數字濾波器的C語言實現，包括高通、低通、帶通濾波器\highpass.c

?????文件???????2806??2013-05-03?15:13??數字濾波器的C語言實現，包括高通、低通、帶通濾波器\lowp.c

?????文件???????2040??2013-05-03?15:14??數字濾波器的C語言實現，包括高通、低通、帶通濾波器\lowpass.c

?????目錄??????????0??2013-05-03?15:26??數字濾波器的C語言實現，包括高通、低通、帶通濾波器

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????????????????31692????????????????????10