在Windows上以wav格式录制音频

Question

我试图在Windows上以wav格式录制音频。但是，记录的字节总是等于零。我是否误解了Windows API中的某些内容？

void RecordSound(void)
{
  static int ChannelOn = 0;
  int err;
  int fp;
  static WAVEFORMATEX fmt;
  static WAVEHDR hdr;
  HWAVEIN hwi = 1;

  fmt.nSamplesPerSec  = 44100;
  fmt.wBitsPerSample  = 16;
  fmt.wFormatTag= WAVE_FORMAT_PCM;
  fmt.nChannels= 2;
  fmt.nBlockAlign     = fmt.wBitsPerSample*fmt.nChannels/8;
  fmt.nAvgBytesPerSec= fmt.nSamplesPerSec*fmt.nBlockAlign;

  hdr.lpData = (LPSTR)buf;
  hdr.dwBufferLength = BUF_SIZE;

  if(!ChannelOn) {
    err = waveInOpen(&hwi, 0, &fmt, 0, 0, 0);
    printf("\nerr = %x\n", err);
    if(!err) {
      waveInAddBuffer(hwi, &hdr, 0);
      waveInStart(hwi);
      puts("Record channel on\n");
      ChannelOn = 1;
    }
  } else {
    waveInClose(hwi);
    puts("Record channel off\n");
    ChannelOn = 0;
    puts("Writing wav to test.wav");
    fp = open("test.wav" , "w");
    write(fp, &fmt, sizeof(WAVEFORMATEX));
    write(fp, &buf, hdr.dwBytesRecorded);
    memset(&hdr, 0 , sizeof(WAVEHDR));
    memset(&fmt, 0 , sizeof(WAVEFORMATEX));
  }
}