pcm实时编码wav ios

用recordedTotalVoiceData 记录总的data数据（用于header的重写）
每次写frame之前 重写header即可

// 将pcm存为wav文件

• (NSString *) getAndCreatePlayableFileFromPcmData:(BOOL)force :(NSData *)frame{

  dispatch_async(self.ioQueue, ^{

    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)self.recordedTotalVoiceData.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;
    
    NSData *ttdata = [NSData dataWithContentsOfFile:self.wavFilePath];
    const char *wavFilePathChar = [self.wavFilePath cStringUsingEncoding:NSUTF8StringEncoding];
    @synchronized (self->_recordedTotalVoiceData) {
        
        FILE *fout = fopen(wavFilePathChar, "r+");
        if (ttdata.length == 0) {
            fclose(fout);
            fout = fopen(wavFilePathChar, "w");
        }
        if(fout == NULL){
            return;
        }
        
        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);
  
    }
  
    NSFileHandle *handle = [NSFileHandle fileHandleForUpdatingAtPath:self.wavFilePath];
    [handle seekToEndOfFile];
    // self.recordedData 为需要保存的pcm数据
    @synchronized (self->_recordedTotalVoiceData) {
        [handle writeData:frame];
    }
  

  });

  return nil;
  }