PCM是采样的原始音频数据, 是无压缩的原始数据, 给pcm添加wav的文件头, 就是wav文件, 所以wav也是一种无损的音频格式. 比pcm多44字节大小的头文件.
oc中给pcm添加wav头文件代码如下:

- (void)addWavHeaderForPcmData:(NSString *)filePath wavPath:(NSString *)wavFilePath {

    FILE *fout;
    short NumChannels = 1;       //录音通道数
    short BitsPerSample = 16;    //线性采样位数
    int SamplingRate = 16000;     //录音采样率(Hz)
    int numOfSamples = (int)[[NSData dataWithContentsOfFile:filePath] length];
    
    int ByteRate = NumChannels*BitsPerSample*SamplingRate/8;
    short BlockAlign = NumChannels*BitsPerSample/8;
    int DataSize = NumChannels*numOfSamples*BitsPerSample/8;
    int chunkSize = 16;
    int totalSize = 46 + DataSize;
    short audioFormat = 1;
    
    if((fout = fopen([wavFilePath cStringUsingEncoding:1], "w")) == NULL) {
        NSLog(@"Error opening out file ");
    }
    
    fwrite("RIFF", sizeof(char), 4,fout);
    fwrite(&totalSize, sizeof(int), 1, fout);
    fwrite("WAVE", sizeof(char), 4, fout);
    fwrite("fmt ", sizeof(char), 4, fout);
    fwrite(&chunkSize, sizeof(int),1,fout);
    fwrite(&audioFormat, sizeof(short), 1, fout);
    fwrite(&NumChannels, sizeof(short),1,fout);
    fwrite(&SamplingRate, sizeof(int), 1, fout);
    fwrite(&ByteRate, sizeof(int), 1, fout);
    fwrite(&BlockAlign, sizeof(short), 1, fout);
    fwrite(&BitsPerSample, sizeof(short), 1, fout);
    fwrite("data", sizeof(char), 4, fout);
    fwrite(&DataSize, sizeof(int), 1, fout);
    
    fclose(fout);
    
    NSMutableData *pamdata = [NSMutableData dataWithContentsOfFile:filePath];
    NSFileHandle *handle;
    handle = [NSFileHandle fileHandleForUpdatingAtPath:wavFilePath];
    [handle seekToEndOfFile];
    [handle writeData:pamdata];
    [handle closeFile];
}