C语言对wav文件计算时域信号的均值、均方值、方差，计算信号的自协方差矩阵

计算时域信号的均值、均方值、方差：

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

int main()
{
    FILE *fp = fopen("test.wav", "rb");
    if (fp == NULL) {
        printf("Failed to open file.\n");
        return 1;
    }

    // 读取wav文件头
    char riff[4], wave[4], fmt[4], data[4];
    unsigned int chunk_size, subchunk1_size, sample_rate, byte_rate, subchunk2_size;
    unsigned short audio_format, num_channels, block_align, bits_per_sample;
    fread(riff, sizeof(char), 4, fp);
    fread(&chunk_size, sizeof(unsigned int), 1, fp);
    fread(wave, sizeof(char), 4, fp);
    fread(fmt, sizeof(char), 4, fp);
    fread(&subchunk1_size, sizeof(unsigned int), 1, fp);
    fread(&audio_format, sizeof(unsigned short), 1, fp);
    fread(&num_channels, sizeof(unsigned short), 1, fp);
    fread(&sample_rate, sizeof(unsigned int), 1, fp);
    fread(&byte_rate, sizeof(unsigned int), 1, fp);
    fread(&block_align, sizeof(unsigned short), 1, fp);
    fread(&bits_per_sample, sizeof(unsigned short), 1, fp);
    fread(data, sizeof(char), 4, fp);
    fread(&subchunk2_size, sizeof(unsigned int), 1, fp);

    // 计算每个样本点的位数
    int sample_size = bits_per_sample / 8;

    // 计算信号长度
    int signal_length = subchunk2_size / sample_size / num_channels;

    // 读取所有样本点
    short *samples = (short*)malloc(sizeof(short) * signal_length);
    for (int i = 0; i < signal_length; i++) {
        fread(&samples[i], sample_size, 1, fp);
    }

    // 计算均值
    double mean = 0;
    for (int i = 0; i < signal_length; i++) {
        mean += samples[i];
    }
    mean /= signal_length;
    printf("Mean: %.2f\n", mean);

    // 计算均方值
    double rms = 0;
    for (int i = 0; i < signal_length; i++) {
        rms += pow(samples[i], 2);
    }
    rms = sqrt(rms / signal_length);
    printf("RMS: %.2f\n", rms);

    // 计算方差
    double variance = 0;
    for (int i = 0; i < signal_length; i++) {
        variance += pow(samples[i] - mean, 2);
    }
    variance /= signal_length;
    printf("Variance: %.2f\n", variance);

    free(samples);
    fclose(fp);
    return 0;
}

计算信号的自协方差矩阵：

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

#define MATRIX_SIZE 10

void auto_correlation_matrix(double *signal, int signal_length, double *matrix)
{
    // 计算均值
    double mean = 0;
    for (int i = 0; i < signal_length; i++) {
        mean += signal[i];
    }
    mean /= signal_length;

    // 计算方差
    double variance = 0;
    for (int i = 0; i < signal_length; i++) {
        variance += pow(signal[i] - mean, 2);
    }
    variance /= signal_length;

    // 计算自协方差矩阵
    for (int i = 0; i < MATRIX_SIZE; i++) {
        for (int j = 0; j < MATRIX_SIZE; j++) {
            double sum = 0;
            for (int k = 0; k < signal_length - abs(i - j); k++) {
                sum += (signal[k + j] - mean) * (signal[k + i] - mean);
            }
            matrix[i * MATRIX_SIZE + j] = sum / (signal_length - abs(i - j)) / variance;
        }
    }
}

int main()
{
    FILE *fp = fopen("test.wav", "rb");
    if (fp == NULL) {
        printf("Failed to open file.\n");
        return 1;
    }

    // 读取wav文件头
    char riff[4], wave[4], fmt[4], data[4];
    unsigned int chunk_size, subchunk1_size, sample_rate, byte_rate, subchunk2_size;
    unsigned short audio_format, num_channels, block_align, bits_per_sample;
    fread(riff, sizeof(char), 4, fp);
    fread(&chunk_size, sizeof(unsigned int), 1, fp);
    fread(wave, sizeof(char), 4, fp);
    fread(fmt, sizeof(char), 4, fp);
    fread(&subchunk1_size, sizeof(unsigned int), 1, fp);
    fread(&audio_format, sizeof(unsigned short), 1, fp);
    fread(&num_channels, sizeof(unsigned short), 1, fp);
    fread(&sample_rate, sizeof(unsigned int), 1, fp);
    fread(&byte_rate, sizeof(unsigned int), 1, fp);
    fread(&block_align, sizeof(unsigned short), 1, fp);
    fread(&bits_per_sample, sizeof(unsigned short), 1, fp);
    fread(data, sizeof(char), 4, fp);
    fread(&subchunk2_size, sizeof(unsigned int), 1, fp);

    // 计算每个样本点的位数
    int sample_size = bits_per_sample / 8;

    // 计算信号长度
    int signal_length = subchunk2_size / sample_size / num_channels;

    // 读取所有样本点
    short *samples = (short*)malloc(sizeof(short) * signal_length);
    for (int i = 0; i < signal_length; i++) {
        fread(&samples[i], sample_size, 1, fp);
    }

    // 计算自协方差矩阵
    double matrix[MATRIX_SIZE * MATRIX_SIZE];
    auto_correlation_matrix(samples, signal_length, matrix);
    for (int i = 0; i < MATRIX_SIZE; i++) {
        for (int j = 0; j < MATRIX_SIZE; j++) {
            printf("%.2f ", matrix[i * MATRIX_SIZE + j]);
        }
        printf("\n");
    }

    free(samples);
    fclose(fp);
    return 0;
}