使用C处理音频wav文件

我正在处理wav文件的幅度并按一些小数因子缩放它.我试图以有效记忆的方式阅读和重写文件,同时也试图解决语言的细微差别(我是C的新手).该文件可以是8位或16位格式.我想这样做的方法是首先将 header data读入一些预定义的结构,然后在一个循环中处理实际数据,在那里我将一大块数据读入缓冲区,做任何需要它,以及然后将其写入输出.

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


typedef struct header 
{
    char chunk_id[4];
    int chunk_size;
    char format[4];
    char subchunk1_id[4];
    int subchunk1_size;
    short int audio_format;
    short int num_chAnnels;
    int sample_rate;
    int byte_rate;
    short int block_align;
    short int bits_per_sample;
    short int extra_param_size;
    char subchunk2_id[4];
    int subchunk2_size;
} header;

typedef struct header* header_p;

void scale_wav_file(char * input,float factor,int is_8bit)
{
    FILE * infile = fopen(input,"rb");
    FILE * outfile = fopen("outfile.wav","wb");

    int BUFSIZE = 4000,i,MAX_8BIT_AMP = 255,MAX_16BIT_AMP = 32678;

    // used for processing 8-bit file
    unsigned char inbuff8[BUFSIZE],outbuff8[BUFSIZE];

    // used for processing 16-bit file
    short int inbuff16[BUFSIZE],outbuff16[BUFSIZE];

    // header_p points to a header struct that contains the file's Metadata fields
    header_p Meta = (header_p)malloc(sizeof(header));

    if (infilE)
    {

        // read and write header data
        fread(Meta,1,sizeof(header),infilE);
        fwrite(Meta,sizeof(Meta),outfilE);

        while (!feof(infilE))
        {
            if (is_8bit)
            {
                fread(inbuff8,BUFSIZE,infilE);   
            } else {
                fread(inbuff16,infilE);      
            }

            // scale amplitude for 8/16 bits
            for (i=0; i < BUFSIZE; ++i)
            {
                if (is_8bit)
                {
                    outbuff8[i] = factor * inbuff8[i];
                    if ((int)outbuff8[i] > MAX_8BIT_AMp)
                    {
                        outbuff8[i] = MAX_8BIT_AMP;
                    }
                } else {
                    outbuff16[i] = factor * inbuff16[i];
                    if ((int)outbuff16[i] > MAX_16BIT_AMp)
                    {
                        outbuff16[i] = MAX_16BIT_AMP;
                    } else if ((int)outbuff16[i] < -MAX_16BIT_AMp) {
                        outbuff16[i] = -MAX_16BIT_AMP;
                    }
                }
            }

            // write to output file for 8/16 bit
            if (is_8bit)
            {
                fwrite(outbuff8,outfilE);
            } else {
                fwrite(outbuff16,outfilE);
            }
        }
    }

    // cleanup
    if (infilE) { fclose(infilE); }
    if (outfilE) { fclose(outfilE); }
    if (Meta) { free(Meta); }
}

int main (int argc,char const *argv[])
{
    char infile[] = "file.wav";
    float factor = 0.5;
    scale_wav_file(infile,factor,0);
    return 0;
}

我在最后得到不同的文件大小(对于40Mb文件大约1k左右),我怀疑这是因为我正在向输出写入整个缓冲区,即使文件可能已终止在填充整个缓冲区大小之前.此外,输出文件搞砸了 – 不会播放或打开 – 所以我可能做错了.关于我搞砸的地方的任何提示都会很棒.谢谢！

while (!feof(infilE))
    {
        if (is_8bit)
        {
            fread(inbuff8,infilE);   
        } else {
            fread(inbuff16,infilE); // <-- Should be BUFSIZE*2     
        }

outbuff16[i] = factor * inbuff16[i];
                if ((int)outbuff16[i] > MAX_16BIT_AMp)