对声卡音频数据采集，实时显示波形

基于VC6.0（MFC）的对声卡音频数据采集，实时显示波形。可以设置采样率、声道、采样位数等参数

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

    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 < n; 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 ---*/

 属性            大小     日期    时间   名称
----------- ---------  ---------- -----  ----

     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

............此处省略44个文件信息