正在解释fftw的.wav数据

我正在尝试读取.wav文件，并找到信号的最高主频。我使用这个主题来读取文件，然后使用函数bytesToFloat将结果转换为float。

最后，在我将数组复制到fftw_complex中后，我运行fftw的计划，找到模数（sqrt(real*real + im*im)）并找到最高值，但结果与信号的频率不匹配，输出通常不是数字。

我使用的.wav文件是维基百科上的110赫兹（A2）频率。

我的问题是：

浮点转换是否正确？

为什么fft后输出矢量返回NaN？

如何读取.wav文件以便使用fftw？

感谢阅读，如有任何帮助，不胜感激。

完整代码：

#include <math.h>
#include <fftw3.h>
#include "Reader.h"
#include <iostream>
#include <string>
#include <fstream>
#include <cstdint>
using namespace std;
typedef struct  WAV_HEADER
{
    /* RIFF Chunk Descriptor */
    uint8_t         RIFF[4];        // RIFF Header Magic header
    uint32_t        ChunkSize;      // RIFF Chunk Size
    uint8_t         WAVE[4];        // WAVE Header
                                    /* "fmt" sub-chunk */
    uint8_t         fmt[4];         // FMT header
    uint32_t        Subchunk1Size;  // Size of the fmt chunk
    uint16_t        AudioFormat;    // Audio format 1=PCM,6=mulaw,7=alaw,     257=IBM Mu-Law, 258=IBM A-Law, 259=ADPCM
    uint16_t        NumOfChan;      // Number of channels 1=Mono 2=Sterio
    uint32_t        SamplesPerSec;  // Sampling Frequency in Hz
    uint32_t        bytesPerSec;    // bytes per second
    uint16_t        blockAlign;     // 2=16-bit mono, 4=16-bit stereo
    uint16_t        bitsPerSample;  // Number of bits per sample
                                    /* "data" sub-chunk */
    uint8_t         Subchunk2ID[4]; // "data"  string
    uint32_t        Subchunk2Size;  // Sampled data length
} wav_hdr;
int getFileSize(FILE* inFile);
float bytesToFloat(int8_t b0, int8_t b1, int8_t b2, int8_t b3);
void WavRead(string fileName, int& samples, float* floatBuffer);
using namespace std;
int main(void) {
    fftw_complex *in, *out;
    fftw_plan p;
    int numSamples=0;
    float* floatBuffer;
    float* dest;
    floatBuffer = (float*)malloc(sizeof(float));
    WavRead("110.wav", numSamples, floatBuffer);
    in = (fftw_complex*)fftw_malloc(numSamples*sizeof(fftw_complex));
    out = (fftw_complex*)fftw_malloc(numSamples*sizeof(fftw_complex));
    for (int i = 0; i < numSamples; i++)
    {
        in[i][0] = floatBuffer[i];
        in[i][1] = (float)0;
    }
    p = fftw_plan_dft_1d(numSamples, in, out, FFTW_FORWARD, FFTW_ESTIMATE);
    fftw_execute(p);
    dest = (float*)malloc(sizeof(float)*numSamples);
    for (int i = 0; i < numSamples; i++) {
        dest[i] = std::sqrt(out[i][0] * out[i][0] + out[i][1] * out[i][1]);
    }
    double max = 0;
    int index=0;
    for (int i = 0; i < numSamples; i++) {
        if (dest[i] > max) {
            max = dest[i];
            index = i;
        }
    }
    cout << endl << index << endl << max << endl;
    fftw_destroy_plan(p);
    fftw_cleanup();
    system("pause");
    return 0;
}
void WavRead(string fileName, int& samples, float* floatBuffer)
{
    wav_hdr wavHeader;
    int headerSize = sizeof(wav_hdr), filelength = 0;
    const char* filePath;
    filePath = fileName.c_str();
    FILE* wavFile = fopen(filePath, "r");
    if (wavFile == nullptr)
    {
        fprintf(stderr, "Unable to open wave file: %sn", filePath);
        system("pause");
    }
    //Read the header
    size_t bytesRead = fread(&wavHeader, 1, headerSize, wavFile);
    if (bytesRead > 0)
    {
        //Read the data
        uint16_t bytesPerSample = wavHeader.bitsPerSample / 8;      //Number     of bytes per sample
        uint64_t numSamples = wavHeader.ChunkSize / bytesPerSample; //How many samples are in the wav file?
        samples = numSamples;
        static const uint16_t BUFFER_SIZE = numSamples*sizeof(float);
        int8_t* buffer = new int8_t[BUFFER_SIZE];
        floatBuffer = (float*)malloc(sizeof(float)*numSamples);
        while ((bytesRead = fread(buffer, sizeof buffer[0], BUFFER_SIZE / (sizeof buffer[0]), wavFile)) > 0)
        {
        }
        for (int i = 0; i < numSamples * 4; i += 4)
        {
            floatBuffer[i / 4] = bytesToFloat(i, i + 1, i + 2, i + 3);
        }
        delete[] buffer;
        buffer = nullptr;
    }
    fclose(wavFile);
}
// find the file size
int getFileSize(FILE* inFile)
{
    int fileSize = 0;
    fseek(inFile, 0, SEEK_END);
    fileSize = ftell(inFile);
    fseek(inFile, 0, SEEK_SET);
    return fileSize;
}
float bytesToFloat(int8_t b0, int8_t b1, int8_t b2, int8_t b3)
{
    int8_t byte_array[] = { b3, b2, b1, b0 };
    float result;
    std::copy(reinterpret_cast<const char*>(&byte_array[0]),
        reinterpret_cast<const char*>(&byte_array[4]),
        reinterpret_cast<char*>(&result));
    return result;
}