如何使用墨西哥帽获取音频文件的频谱 [英] How to get spectrum of audo file using mexican hat

问题描述

我有一个扩展名为wav的声音文件。我得到了这个文件的幅度值。然后我使用y =（1-t * t）* exp（-1 * t * t / 2）生成墨西哥帽小波的值。现在我需要获取此音频文件的频谱。这该怎么做。这是我的代码



我尝试过：

I have a sound file with the extension wav. I got the amplitude values of this file. Then I generated values of Mexican hat wavelet using y = (1-t*t)*exp(-1*t*t/2). Now I need to get the spectrum of this audio file. How to do this. Here is my code

What I have tried:

#include <iostream>
#include "WavData.cpp"
#include <graphics.h>
#include<stdio.h>
#include<math.h>

#define PI 3.141592653589793238462643383279502884197169399375105820974
using namespace std;
using namespace yazz::audio;
//drawing function
void DrawSamples(const double* source, int dataLen, int start, int finish){
 for(int i = start; i < finish; i++){
        if(i == start) moveto((getmaxx()-30)*i/(finish - start)+10, getmaxy()/2 - source[i]);
        else
        lineto((getmaxx()-30)*i/(finish - start)+10, getmaxy()/2 - source[i]);
        }
     }
/**************mexican hat(ricker) function*************************************/
double Mhat(double time, double a, double b)
{
   double mhat;
   mhat = 200*(2/(sqrt(3)*pow(PI, 1./4)))*(1-pow((time-b)/a,2))*exp(-1*pow((time-b)/a,2)/2);
   return mhat;
           }
/**************************************************/

int main(){    
WavData* wavData = WavData::readFromFile("son.wav");//read aduio file
const double *normalizedData = wavData->getNormalizedData();//to get values of audio file
int dataLength = wavData->getNumberOfSamples();//to get length of audio file values

/******************************************/
initwindow(1300, 600, "Mexican hat", 0, 0, false, true);
setbkcolor(WHITE);
cleardevice();
setcolor(CYAN);
/******************ricker*************************/
//generate mexican hat
double m = -5, n = 5, dt = 0.15625, a = 1, b = 0;//dt = 0.15625
int length = (n - m)/0.15625;//0.15625

double* time = new double[length];
//fill time[]
for(int i = 0; i < length; i++)
{
        time[i] = m;
        m = m + dt;
        }

double* mhat = new double[length];
//here I get values of mexican hat wavelet
for(int j = 0; j < length; j++){
mhat[j] = Mhat(time[j], a, b);
}

//now what need I to do

 delete[] normalizedData;
 delete[] time;
 delete[] mhat;

getch();    
return 0;
}

推荐答案

获取信号频谱以使用傅里叶变换的常用技术，通常是FFT。 此页有一个示例程序[ ^ ]。



顺便说一下，你可能更喜欢包括math.h与宏_USE_MATH_DEFINES定义。该文件具有最常见的数学常数的定义，如pi，e等.pi的值在常量M_PI中定义。

The usual technique for obtaining the spectrum of a signal to use a Fourier transform, most often the FFT. There is one example program at this page[^].

By the way, you might prefer to include math.h with the macro _USE_MATH_DEFINES defined. That file has definitions of most common mathematical constants like pi, e, etc. The value of pi is defined in the constant M_PI.

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