c语言实现对wav音频分帧加窗谱减法例子

好的，我可以为你提供一个c语言实现对wav音频分帧加窗谱减法的例子。

首先，你需要使用一个wav文件解析库来读取wav文件的头信息和数据。然后，你需要将音频数据分帧，每帧的长度通常是20-40毫秒。之后，对每一帧进行加窗处理，常用的窗函数有汉明窗、海宁窗等。再对每一帧进行FFT变换，得到幅度谱和相位谱。对于每两帧之间的差异，可以用谱减法进行处理，即用当前帧的幅度谱减去前一帧的幅度谱作为当前帧的特征。

以下是一个简单的示例代码：

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

#define PI 3.14159265358979323846

//wav文件头数据结构
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;

//加窗函数：汉明窗
void hammingWindow(double* frame, int frameLen) {
    for(int i = 0; i < frameLen; i++)
        frame[i] *= 0.54 - 0.46 * cos(2 * PI * i / (frameLen - 1));
}

//快速傅里叶变换
void fft(double* x, double* y, int n) {
    if(n == 1)
        return;

    //递归计算前半部分和后半部分的FFT
    fft(x, y, n/2);
    fft(x+n/2, y+n/2, n/2);

    //合并前后两部分的结果
    for(int i = 0; i < n/2; i++) {
        double wx = cos(2 * PI * i / n);
        double wy = sin(2 * PI * i / n);
        double ax = x[i];
        double ay = y[i];
        double bx = x[i+n/2] * wx - y[i+n/2] * wy;
        double by = x[i+n/2] * wy + y[i+n/2] * wx;
        x[i] = ax + bx;
        y[i] = ay + by;
        x[i+n/2] = ax - bx;
        y[i+n/2] = ay - by;
    }
}

int main() {
    char* filename = "sample.wav";
    FILE* fp = fopen(filename, "r");
    if(fp == NULL) {
        printf("Error: Failed to open file %s!\n", filename);
        return 1;
    }

    WavHeader header;
    fread(&header, sizeof(header), 1, fp);

    //读取音频采样率和帧长
    int numChannels = header.numChannels;
    int sampleRate = header.sampleRate;
    int frameLen = sampleRate / 100; //帧长为10ms

    //跳过头信息
    fseek(fp, header.subChunk1Size - 16, SEEK_CUR);
    if(header.subChunk1Size > 16)
        fseek(fp, header.subChunk1Size - 16, SEEK_CUR);

    //读取音频数据
    int numFrames = header.subChunk2Size / numChannels / (header.bitsPerSample/8) / frameLen;
    double* data = (double*)malloc(numFrames * frameLen * sizeof(double));
    for(int i = 0; i < numFrames * frameLen; i++) {
        short sample;
        fread(&sample, sizeof(short), 1, fp);
        data[i] = (double)sample / 32768.0;
    }
    fclose(fp);

    //分帧加窗、傅里叶变换和谱减法处理
    double* frame = (double*)malloc(frameLen * sizeof(double));
    double* window = (double*)malloc(frameLen * sizeof(double));
    double* spec = (double*)malloc(frameLen * sizeof(double));
    double* prevSpec = (double*)malloc(frameLen * sizeof(double));
    double* diffSpec = (double*)malloc(frameLen * sizeof(double));
    for(int i = 0; i < numFrames; i++) {
        //取当前帧
        for(int j = 0; j < frameLen; j++)
            frame[j] = data[i * frameLen + j];

        //加汉明窗
        hammingWindow(frame, frameLen);

        //计算幅度谱
        for(int j = 0; j < frameLen; j++) {
            spec[j] = frame[j];
            prevSpec[j] = diffSpec[j];
            diffSpec[j] = 0;
        }
        fft(spec, diffSpec, frameLen);
        for(int j = 0; j < frameLen; j++)
            spec[j] = sqrt(spec[j] * spec[j] + diffSpec[j] * diffSpec[j]);

        //谱减法处理
        if(i > 1) {
            for(int j = 0; j < frameLen; j++) {
                double diff = spec[j] - prevSpec[j];
                if(diff < 0)
                    diff = 0;
                spec[j] = diff;
            }
        }

        //输出当前帧的特征
        for(int j = 0; j < frameLen; j++)
            printf("%.2f ", spec[j]);
        printf("\n");
    }

    free(data);
    free(frame);
    free(window);
    free(spec);
    free(prevSpec);
    free(diffSpec);

    return 0;
}

在上面的代码中，我们使用了汉明窗对每一帧数据进行加窗处理，并采用FFT算法计算幅度谱。在谱减法处理中，使用了前一帧的幅度谱作为参考，计算当前帧特征时将当前帧的幅度谱减去前一帧的幅度谱。

希望这个例子能够对你有所帮助！