使用fopen_s怎么求wav的时域信号功率谱使用fft算法

以下是使用fopen_s和FFT算法计算WAV文件的时域信号功率谱的示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#define PI 3.14159265358979323846

// WAV文件头结构体
typedef struct {
    char chunkID[4];
    unsigned int chunkSize;
    char format[4];
    char subchunk1ID[4];
    unsigned int subchunk1Size;
    unsigned short audioFormat;
    unsigned short numChannels;
    unsigned int sampleRate;
    unsigned int byteRate;
    unsigned short blockAlign;
    unsigned short bitsPerSample;
    char subchunk2ID[4];
    unsigned int subchunk2Size;
} WAVHeader;

// 计算FFT
void fft(double *x, double *y, int n)
{
    int i, j, k;
    double c, s, t1, t2;
    double *p, *q;

    for (i = 0; i < n; i++) {
        j = 0;
        k = i;
        while (k > 0) {
            j = (j << 1) | (k & 1);
            k >>= 1;
        }
        if (j < i) {
            t1 = x[i];
            t2 = y[i];
            x[i] = x[j];
            y[i] = y[j];
            x[j] = t1;
            y[j] = t2;
        }
    }

    for (k = 1; k < n; k <<= 1) {
        c = cos(PI / k);
        s = sin(PI / k);
        p = x + k;
        q = y + k;
        for (j = 0; j < n; j += k << 1) {
            t1 = 1.0;
            t2 = 0.0;
            for (i = 0; i < k; i++) {
                t3 = t1 * p[i] - t2 * q[i];
                t2 = t1 * q[i] + t2 * p[i];
                p[i] = x[j + i] - t3;
                q[i] = y[j + i] - t2;
                x[j + i] += t3;
                y[j + i] += t2;
                t1 = c * t1 - s * t2;
                t2 = s * t1 + c * t2;
            }
        }
    }
}

int main()
{
    FILE *fp;
    WAVHeader header;
    double *data, *power;
    int i, N;

    // 打开WAV文件
    if (fopen_s(&fp, "test.wav", "rb") != 0) {
        printf("Failed to open WAV file!\n");
        return 1;
    }

    // 读取WAV文件头
    fread(&header, sizeof(WAVHeader), 1, fp);

    // 计算信号长度
    N = header.subchunk2Size / (header.bitsPerSample / 8);

    // 分配内存
    data = (double*)malloc(N * sizeof(double));
    power = (double*)malloc(N / 2 * sizeof(double));

    // 读取信号数据
    for (i = 0; i < N; i++) {
        if (header.bitsPerSample == 8) {
            data[i] = (double)(char)fgetc(fp) / 128.0;
        } else if (header.bitsPerSample == 16) {
            data[i] = (double)(short)fgetc(fp) / 32768.0;
            data[i] += (double)(short)fgetc(fp) / 32768.0;
        }
    }

    // 关闭WAV文件
    fclose(fp);

    // 计算FFT
    fft(data, power, N);

    // 计算功率谱
    for (i = 0; i < N / 2; i++) {
        power[i] = power[i] * power[i] / (N * N);
    }

    // 输出功率谱
    for (i = 0; i < N / 2; i++) {
        printf("%d %lf\n", i, power[i]);
    }

    // 释放内存
    free(data);
    free(power);

    return 0;
}

该代码可以读取名为"test.wav"的WAV文件，计算其时域信号的功率谱，并输出到控制台。其中，fft函数是用于计算FFT的，data数组存储读取的信号数据，power数组存储计算得到的功率谱数据。需要注意的是，在读取信号数据时，需要根据WAV文件的位深度进行处理，示例代码中处理了8位和16位的情况。另外，计算完FFT后，需要将每个频率分量的幅值平方再除以信号长度和FFT长度的积，才是该频率分量的功率。最后，需要释放分配的内存。