使用fopen_s怎么求wav的时域信号功率谱
时间: 2024-05-11 16:15:26 浏览: 5
首先,需要打开WAV文件并读取其数据。可以使用以下代码:
```c
FILE* fp;
errno_t err = fopen_s(&fp, "audio.wav", "rb"); // 打开WAV文件
if (err != 0) {
printf("无法打开文件\n");
return 0;
}
// 读取数据
char chunkID[4];
uint32_t chunkSize;
char format[4];
char subchunk1ID[4];
uint32_t subchunk1Size;
uint16_t audioFormat;
uint16_t numChannels;
uint32_t sampleRate;
uint32_t byteRate;
uint16_t blockAlign;
uint16_t bitsPerSample;
char subchunk2ID[4];
uint32_t subchunk2Size;
fread(chunkID, 1, 4, fp);
fread(&chunkSize, 4, 1, fp);
fread(format, 1, 4, fp);
fread(subchunk1ID, 1, 4, fp);
fread(&subchunk1Size, 4, 1, fp);
fread(&audioFormat, 2, 1, fp);
fread(&numChannels, 2, 1, fp);
fread(&sampleRate, 4, 1, fp);
fread(&byteRate, 4, 1, fp);
fread(&blockAlign, 2, 1, fp);
fread(&bitsPerSample, 2, 1, fp);
fread(subchunk2ID, 1, 4, fp);
fread(&subchunk2Size, 4, 1, fp);
// 读取音频数据
int16_t* data = (int16_t*)malloc(subchunk2Size);
fread(data, 2, subchunk2Size/2, fp);
fclose(fp);
```
然后,可以使用FFT算法计算信号的功率谱。可以使用某个现成的FFT库,或者自己实现FFT算法。以下是使用FFTW库计算功率谱的代码:
```c
#include <fftw3.h>
// 计算幅值谱
void computeMagnitudeSpectrum(fftw_complex* spectrum, int n, double* magnitude) {
for (int i = 0; i < n; i++) {
magnitude[i] = sqrt(spectrum[i][0] * spectrum[i][0] + spectrum[i][1] * spectrum[i][1]);
}
}
// 计算功率谱
void computePowerSpectrum(int16_t* data, int n, double sampleRate, double* powerSpectrum) {
// 分配内存
fftw_complex* in = (fftw_complex*)fftw_malloc(sizeof(fftw_complex) * n);
fftw_complex* out = (fftw_complex*)fftw_malloc(sizeof(fftw_complex) * n);
fftw_plan plan = fftw_plan_dft_1d(n, in, out, FFTW_FORWARD, FFTW_ESTIMATE);
// 复制输入数据到复数数组中
for (int i = 0; i < n; i++) {
in[i][0] = data[i];
in[i][1] = 0;
}
// 执行FFT
fftw_execute(plan);
// 计算幅值谱
double* magnitude = (double*)malloc(sizeof(double) * n);
computeMagnitudeSpectrum(out, n, magnitude);
// 计算功率谱
for (int i = 0; i < n / 2 + 1; i++) {
powerSpectrum[i] = magnitude[i] * magnitude[i] / (n * sampleRate);
}
// 释放内存
fftw_destroy_plan(plan);
fftw_free(in);
fftw_free(out);
free(magnitude);
}
```
最后,可以使用以下代码调用上述函数并输出功率谱:
```c
double sampleRate = (double)sampleRate;
int n = subchunk2Size / 2;
double* powerSpectrum = (double*)malloc(sizeof(double) * (n / 2 + 1));
computePowerSpectrum(data, n, sampleRate, powerSpectrum);
for (int i = 0; i < n / 2 + 1; i++) {
printf("%f\n", powerSpectrum[i]);
}
free(powerSpectrum);
```