操作pcm数据，pcm转wav

参考资料
视音频数据处理入门：PCM音频采样数据处理: https://blog.csdn.net/leixiaohua1020/article/details/50534316
WAV文件格式详解: https://blog.csdn.net/imxiangzi/article/details/80265978
在看雷神的pcm采样数据处理的文章时，看到了最后一个章节pcm转wav，测试了下，但是最后生成的wav文件没法用windowsplayer打开。
下载了一个正常的wav文件，发现可以播放，可以肯定的是代码里封装的格式有问题。
用ultraedit比对了下，发现了有几处不正常的地方，就顺便给改了。
代码如下：

#include <stdio.h>
/**
 * Split Left and Right channel of 16LE PCM file.
 * @param url  Location of PCM file.
 *
 */
int simplest_pcm16le_split(char *url){
    FILE *fp=fopen(url,"rb+");
    FILE *fp1=fopen("output_l.pcm","wb+");
    FILE *fp2=fopen("output_r.pcm","wb+");
 
    unsigned char *sample=(unsigned char *)malloc(4);
 
    while(!feof(fp)){
        fread(sample,1,4,fp);
        //L
        fwrite(sample,1,2,fp1);
        //R
        fwrite(sample+2,1,2,fp2);
    }
 
    free(sample);
    fclose(fp);
    fclose(fp1);
    fclose(fp2);
    return 0;
}


/**
 * Halve volume of Left channel of 16LE PCM file
 * @param url  Location of PCM file.
 */
int simplest_pcm16le_halfvolumeleft(char *url){
    FILE *fp=fopen(url,"rb+");
    FILE *fp1=fopen("output_halfleft.pcm","wb+");
 
    int cnt=0;
 
    unsigned char *sample=(unsigned char *)malloc(4);
 
    while(!feof(fp)){
        short *samplenum=NULL; // short 占用2字节
        fread(sample,1,4,fp);
 
        samplenum=(short *)sample;
        *samplenum=*samplenum/2;
        //L
        fwrite(sample,1,2,fp1);
        //R
        fwrite(sample+2,1,2,fp1);
 
        cnt++;
    }
    printf("Sample Cnt:%d\n",cnt);
 
    free(sample);
    fclose(fp);
    fclose(fp1);
    return 0;
}


/**
 * Re-sample to double the speed of 16LE PCM file
 * @param url  Location of PCM file.
 */
int simplest_pcm16le_doublespeed(char *url){
    FILE *fp=fopen(url,"rb+");
    FILE *fp1=fopen("output_doublespeed.pcm","wb+");
 
    int cnt=0;
 
    unsigned char *sample=(unsigned char *)malloc(4);
 
    while(!feof(fp)){
 
        fread(sample,1,4,fp);
 
        if(cnt%2!=0){
            //L
            fwrite(sample,1,2,fp1);
            //R
            fwrite(sample+2,1,2,fp1);
        }
        cnt++;
    }
    printf("Sample Cnt:%d\n",cnt);
 
    free(sample);
    fclose(fp);
    fclose(fp1);
    return 0;
}

/**
 * Convert PCM-16 data to PCM-8 data.
 * @param url  Location of PCM file.
 */
int simplest_pcm16le_to_pcm8(char *url){
    FILE *fp=fopen(url,"rb+");
    FILE *fp1=fopen("output_8.pcm","wb+");
 
    int cnt=0;
 
    unsigned char *sample=(unsigned char *)malloc(4);
 
    while(!feof(fp)){
 
        short *samplenum16=NULL;
        char samplenum8=0;
        unsigned char samplenum8_u=0;
        fread(sample,1,4,fp);
        //(-32768-32767)
        samplenum16=(short *)sample;
        samplenum8=(*samplenum16)>>8;
        //(0-255)
        samplenum8_u=samplenum8+128;
        //L
        fwrite(&samplenum8_u,1,1,fp1);
 
        samplenum16=(short *)(sample+2);
        samplenum8=(*samplenum16)>>8;
        samplenum8_u=samplenum8+128;
        //R
        fwrite(&samplenum8_u,1,1,fp1);
        cnt++;
    }
    printf("Sample Cnt:%d\n",cnt);
 
    free(sample);
    fclose(fp);
    fclose(fp1);
    return 0;
}

/**
 * Cut a 16LE PCM single channel file.
 * @param url        Location of PCM file.
 * @param start_num  start point
 * @param dur_num    how much point to cut
 */
int simplest_pcm16le_cut_singlechannel(char *url,int start_num,int dur_num){
    FILE *fp=fopen(url,"rb+");
    FILE *fp1=fopen("output_cut.pcm","wb+");
    FILE *fp_stat=fopen("output_cut.txt","wb+");
 
    unsigned char *sample=(unsigned char *)malloc(2);
 
    int cnt=0;
    while(!feof(fp)){
        fread(sample,1,2,fp);
        if(cnt>start_num&&cnt<=(start_num+dur_num)){
            fwrite(sample,1,2,fp1);
 
            short samplenum=sample[1];
            samplenum=samplenum*256;
            samplenum=samplenum+sample[0];
 
            fprintf(fp_stat,"%6d,",samplenum);
            if(cnt%10==0)
                fprintf(fp_stat,"\n",samplenum);
        }
        cnt++;
    }
 
    free(sample);
    fclose(fp);
    fclose(fp1);
    fclose(fp_stat);
    return 0;
}


/**
 * Convert PCM16LE raw data to WAVE format
 * @param pcmpath      Input PCM file.
 * @param channels     Channel number of PCM file.
 * @param sample_rate  Sample rate of PCM file.
 * @param wavepath     Output WAVE file.
 */
int simplest_pcm16le_to_wave(const char *pcmpath,int channels,int sample_rate,int bits,
    const char *wavepath)
{
        //int bits = 16; // 每个channel每次采样的精度，占多少位 BitsPerSample
typedef unsigned int uint32;
typedef unsigned short uint16;

    typedef struct WAVE_HEADER{  
        char             fccID[4];    // "RIFF"
        uint32            dwSize;     // 44 + WAVE_DATA->dwSize   小端模式    
        char             fccType[4]; // "WAVE"   
    }WAVE_HEADER;  

    // 24
    typedef struct WAVE_FMT{  
        char                  fccID[4];          // "fmt "    
        uint32       dwSize;           // 16 小端模式     表示该区块数据的长度（不包含ID和Size的长度）      
        uint16     wFormatTag;        // AudioFormat表示Data区块存储的音频数据的格式，PCM音频数据的值为1   小端模式    
        uint16     wChannels;         // NumChannels表示音频数据的声道数，1：单声道，2：双声道 小端模式    
        uint32       dwSamplesPerSec;  // 采样率 小端模式    
        uint32       dwAvgBytesPerSec;  //  小端模式    
        uint16     wBlockAlign; // BlockAlign每个采样所需的字节数 = NumChannels * BitsPerSample / 8 小端模式    
        uint16     uiBitsPerSample;  //BitsPerSample每个采样存储的bit数，8：8bit，16：16bit，32：32bit 小端模式    
    }WAVE_FMT;  

    // 8B
    typedef struct WAVE_DATA{  
        char       fccID[4]; // "data"         
        uint32         dwSize;    // Size表示音频数据的长度，N = ByteRate * seconds 小端模式            
    }WAVE_DATA;  
 
 
    if(channels==0||sample_rate==0){
    channels = 2;
    sample_rate = 44100;
    }
    
 
    WAVE_HEADER   pcmHEADER;  
    WAVE_FMT   pcmFMT;  
    WAVE_DATA   pcmDATA;  
 
    unsigned   short   m_pcmData;
    FILE   *fp,*fpout;  
 
    fp=fopen(pcmpath, "rb");
    if(fp == NULL) {  
        printf("open pcm file error\n");
        return -1;  
    }
    fpout=fopen(wavepath,   "wb+");
    if(fpout == NULL) {    
        printf("create wav file error\n");  
        return -1; 
    }        
    //WAVE_HEADER
    memcpy(pcmHEADER.fccID,"RIFF",strlen("RIFF"));                    
    memcpy(pcmHEADER.fccType,"WAVE",strlen("WAVE"));  
    fseek(fpout,sizeof(WAVE_HEADER),1); 
    //WAVE_FMT
    pcmFMT.dwSamplesPerSec=sample_rate; 
    //  比特率 = SampleRate * NumChannels * BitsPerSample / 8
    pcmFMT.dwAvgBytesPerSec=pcmFMT.dwSamplesPerSec*channels*bits/8;  
    pcmFMT.uiBitsPerSample=bits;    
    memcpy(pcmFMT.fccID,"fmt ",strlen("fmt "));  
    pcmFMT.dwSize=16; 
    // BlockAlign每个采样所需的字节数 = NumChannels * BitsPerSample / 8
    pcmFMT.wBlockAlign=channels * bits / 8;  
    pcmFMT.wChannels=channels;  
    pcmFMT.wFormatTag=1;  
 
    fwrite(&pcmFMT,sizeof(WAVE_FMT),1,fpout); 
 
    //WAVE_DATA;
    memcpy(pcmDATA.fccID,"data",strlen("data"));  
    pcmDATA.dwSize=0;
    fseek(fpout,sizeof(WAVE_DATA),SEEK_CUR);
 
    fread(&m_pcmData,sizeof(unsigned short),1,fp);
    while(!feof(fp)){  
        pcmDATA.dwSize+=2;
        fwrite(&m_pcmData,sizeof(unsigned short),1,fpout);
        fread(&m_pcmData,sizeof(unsigned short),1,fp);
    }  
 
    pcmHEADER.dwSize=sizeof(WAVE_FMT) + sizeof(WAVE_DATA) + 4 +pcmDATA.dwSize;
 
    rewind(fpout);
    fwrite(&pcmHEADER,sizeof(WAVE_HEADER),1,fpout);
    fseek(fpout,sizeof(WAVE_FMT),SEEK_CUR);
    fwrite(&pcmDATA,sizeof(WAVE_DATA),1,fpout);
    
    fclose(fp);
    fclose(fpout);
 
    return 0;
}


int main()
{
    simplest_pcm16le_split("NocturneNo2inEflat_44.1k_s16le.pcm");

    simplest_pcm16le_halfvolumeleft("NocturneNo2inEflat_44.1k_s16le.pcm");

    simplest_pcm16le_doublespeed("NocturneNo2inEflat_44.1k_s16le.pcm");

    simplest_pcm16le_to_pcm8("NocturneNo2inEflat_44.1k_s16le.pcm");
    
    //simplest_pcm16le_cut_singlechannel("drum.pcm",2360,120);
    
    simplest_pcm16le_to_wave("NocturneNo2inEflat_44.1k_s16le.pcm",2,
                             44100, 16, "output_nocturne.wav");
    return 0;
}