/*================================================================================

????fftdom.cpp??-??Copyright?（C）?1997?by?Don?Cross?
???????????????????http://www.intersrv.com/~dcross/fft.html

????This?C++?source?file?contains?a?function?for?finding?the?dominant?
????frequency?in?an?output?buffer?calculated?by?the?FFT?algorithm.

================================================================================*/
#include?“stdafx.h“

#include?

//?This?function?returns?the?dominant?frequency?in?Hz.

double?FindDominantFrequency?（
????int?numSamples???????????//?total?number?of?frequency?samples?in?buffer
????int?windowSize???????????//?width?of?search?window?（experiment?with?this;?try?4）
????double?*real?????????????//?real?coefficient?buffer
????double?*imag?????????????//?imaginary?coefficient?buffer
????double?*ampl?????????????//?work?buffer?for?holding?r*r+i*i?values
????double?samplingRate?）?????//?sampling?rate?expressed?in?samples/second?[Hz]
{
????const?int?n?=?numSamples/2;???//?number?of?positive?frequencies.

????//?Pre-calculate?amplitude?values?in?the?buffer?provided?by?the?caller.
????//?This?makes?the?code?a?lot?more?efficient.

????for?（?int?i=0;?i????{
????????ampl[i]?=?real[i]*real[i]?+?imag[i]*imag[i];
????}

????//?Zero?out?amplitudes?for?frequencies?below?20?Hz.
????int?low?=?int?（?numSamples?*?20.0?/?samplingRate?）;
????assert?（?low>=0?&&?low????for?（?i=low;?i>=0;?i--?）
????{
????????ampl[i]?=?0.0;
????}

????//?In?the?following?loop?i1?is?the?left?side?of?the?window
????//?and?i2?is?the?right?side.

????double?maxWeight?=?-1.0;
????double?centerFreq?=?-1.0;

????for?（?int?i2?=?windowSize;?i2?????{
????????const?int?i1?=?i2?-?windowSize;

????????double?moment?=?0.0;
????????double?weight?=?0.0;

????????for?（?int?i=i1;?i<=i2;?i++?）
????????{
????????????weight?+=?ampl[i];
????????????moment?+=?double（i）?*?ampl[i];
????????}

????????if?（?weight?>?maxWeight?）
????????{
????????????maxWeight?=?weight;
????????????centerFreq?=?moment?/?weight;
????????}
????}

????return?samplingRate?*?centerFreq?/?double（numSamples）;
}

/*---?end?of?file?fftdom.cpp?---*/

?屬性????????????大小?????日期????時(shí)間???名稱(chēng)
-----------?---------??----------?-----??----

?????文件????????415??1996-06-04?19:18??RECORD\DDCMATH.H

?????文件??????11062??2009-09-27?10:24??RECORD\Debug\BuildLog.htm

?????文件??????????0??2009-09-30?11:23??RECORD\Debug\data.txt

?????文件???????4233??2009-09-27?13:11??RECORD\Debug\Fftdom.obj

?????文件??????????0??2009-09-27?13:11??RECORD\Debug\Fftdom.sbr

?????文件???????5037??2009-09-27?13:10??RECORD\Debug\Fftmisc.obj

?????文件??????????0??2009-09-27?13:10??RECORD\Debug\Fftmisc.sbr

?????文件???????6609??2009-09-27?13:10??RECORD\Debug\Fourierd.obj

?????文件??????????0??2009-09-27?13:10??RECORD\Debug\Fourierd.sbr

?????文件???????6571??2009-09-27?13:10??RECORD\Debug\Fourierf.obj

?????文件??????????0??2009-09-27?13:10??RECORD\Debug\Fourierf.sbr

?????文件?????????67??2009-09-27?10:23??RECORD\Debug\mt.dep

?????文件?????450092??2009-09-27?16:02??RECORD\Debug\Noname.wav

?????文件?????450048??2009-09-27?16:02??RECORD\Debug\Noname.wav.dat

?????文件????4015104??2009-09-27?13:11??RECORD\Debug\Record.bsc

?????文件????1306709??2009-09-27?13:11??RECORD\Debug\Record.exe

?????文件????????146??2009-09-25?12:43??RECORD\Debug\Record.exe.embed.manifest

?????文件????????212??2009-09-25?12:43??RECORD\Debug\Record.exe.embed.manifest.res

?????文件????????145??2009-09-27?10:23??RECORD\Debug\Record.exe.intermediate.manifest

?????文件????5916584??2009-09-27?13:11??RECORD\Debug\Record.ilk

?????文件??????16512??2009-09-27?13:10??RECORD\Debug\Record.obj

?????文件??????18196??2009-09-25?14:17??RECORD\Debug\Record.res

?????文件??????????0??2009-09-27?13:10??RECORD\Debug\Record.sbr

?????文件??????48658??2009-09-27?13:09??RECORD\Debug\RecordDlg.obj

?????文件??????????0??2009-09-27?13:10??RECORD\Debug\RecordDlg.sbr

?????文件?????101871??2009-09-27?13:09??RECORD\Debug\Scope.obj

?????文件??????????0??2009-09-27?13:10??RECORD\Debug\Scope.sbr

?????文件?????106019??2009-09-27?13:09??RECORD\Debug\StdAfx.obj

?????文件????1358043??2009-09-27?13:09??RECORD\Debug\STDAFX.sbr

?????文件?????238592??2009-09-27?13:11??RECORD\Debug\vc60.idb

............此處省略44個(gè)文件信息