audio - 如何从通过远程桌面访问的 PC 的音频输入进行录制？

Question

我正在用 Borland Turbo C++ (2006) 编写一个应用程序，并在 Windows XP Pro 下运行，我想在其中将音频输入记录到数据缓冲区中，以便随后对时间响应进行 FFT。

当应用程序在本地运行时，以下代码可以正常工作:

short int       pluck_data[T_SAMPLES][CHANNELS];

//---------------------------------------------------------------------------

int __fastcall CheckResult(char* func_name, int result)
{
  int   return_value = 1;           // set return_value for fail by default
  char  msg[100];

  if(result == MMSYSERR_NOERROR)    // function call returned without error
    return_value = 0;
  else                              // function call returned error
  {
    switch(result)
    {
      case MMSYSERR_ALLOCATED:
        sprintf(msg, "%s: Specified resource is already allocated.", func_name);
        break;
      case MMSYSERR_BADDEVICEID:
        sprintf(msg, "%s: Specified device identifier is out of range.", func_name);
        break;
      case MMSYSERR_INVALHANDLE:
        sprintf(msg, "%s: Specified device handle is invalid.", func_name);
        break;
      case MMSYSERR_NODRIVER:
        sprintf(msg, "%s: No device driver is present.", func_name);
        break;
      case MMSYSERR_NOMEM:
        sprintf(msg, "%s: Unable to allocate or lock memory.", func_name);
        break;
      case WAVERR_BADFORMAT:
        sprintf(msg, "%s: Attempted to open with an unsupported waveform-audio format.", func_name);
        break;
      case WAVERR_STILLPLAYING:
        sprintf(msg, "%s: The buffer pointed to by the pwh parameter is still in the queue.", func_name);
        break;
      case WAVERR_UNPREPARED:
        sprintf(msg, "%s: The buffer pointed to by the pwh parameter hasn't been prepared.", func_name);
        break;
      default:
        sprintf(msg, "%s: Unknown error.", func_name);
    }
    ReportError(hWnd, msg, log_fptr);
  } // else function call returned error
  return return_value;
}

//---------------------------------------------------------------------------

int __fastcall RecordString()
{
  int           return_value = 1;           // set return_value for fail by default
  WAVEINCAPS    dev_capability;
  HWAVEIN       dev_handle;
  WAVEFORMATEX  rec_format;
  WAVEHDR       rec_header;
  int           result;
  char          msg[100];

  result = waveInGetNumDevs();      // get number of audio input devices
  if(result != 1)
  {
    if(result == 0)
      sprintf(msg, "No waveform-audio input devices present.");
    else
      sprintf(msg, "More than one waveform-audio input device present.");
    ReportError(hWnd, msg, log_fptr);
  }
  else
  {
    // only 1 audio input device; test its capabilities
    result = waveInGetDevCaps(0,&dev_capability,sizeof(dev_capability));
    if(CheckResult("waveInGetDevCaps", result) == 0)
    {
      // test if device supports 96kHz, Stereo, 16-bit format WAVE_FORMAT_96S16
      if ((dev_capability.dwFormats & WAVE_FORMAT_96S16) == 0)
      {
        sprintf(msg, "waveInGetDevCaps: WAVE_FORMAT_96S16 not supported");
        ReportError(hWnd, msg, log_fptr);
      }
      else
      {
        // initialise required record format
        rec_format.wFormatTag = WAVE_FORMAT_PCM;
        rec_format.nChannels = CHANNELS;                                    // 2
        rec_format.nSamplesPerSec = SAMPLE_RATE;                            // 96000
        rec_format.nAvgBytesPerSec = BYTES_PER_SAMPLE * SAMPLE_RATE;        // 384000
        rec_format.nBlockAlign = BYTES_PER_SAMPLE;                          // 4
        rec_format.wBitsPerSample = SAMPLE_BITS;                            // 16
        rec_format.cbSize = 0;
        // open audio input device requesting format 96kHz, Stereo, 16-bit
        result = waveInOpen(&dev_handle, WAVE_MAPPER, &rec_format, 0, 0, 0);
        if(CheckResult("waveInOpen", result) == 0)
        {
          // initialise header for data buffer
          rec_header.lpData = (char*)&pluck_data;
          rec_header.dwBufferLength = sizeof(pluck_data);
          rec_header.dwFlags = 0;
          // prepare header for data buffer
          result = waveInPrepareHeader(dev_handle, &rec_header, sizeof(rec_header));
          if(CheckResult("waveInPrepareHeader", result) == 0)
          {
            // connect data buffer to audio input device
            result = waveInAddBuffer(dev_handle, &rec_header, sizeof(rec_header));
            if(CheckResult("waveInAddBuffer", result) == 0)
            {
              // start recording
              result = waveInStart(dev_handle);
              if(CheckResult("waveInStart", result) == 0)
              {
                // recording - poll flag until data buffer full
                while((rec_header.dwFlags & WHDR_DONE ) == 0); // wait for flag to be set
                // buffer now full
                // reset/stop recording
                result = waveInReset(dev_handle);
                if(CheckResult("waveInReset", result) == 0)
                {
                  // unprepare header for data buffer
                  result = waveInUnprepareHeader(dev_handle, &rec_header, sizeof(rec_header));
                  if(CheckResult("waveInUnprepareHeader", result) == 0)
                  {
                    // close audio input device
                    result = waveInClose(dev_handle);
                    if(CheckResult("waveInClose", result) == 0)
                      return_value = 0;
                  }
                }
              }
            }
          }
        }
      }
    }
  }
  return return_value;
}

但是，如果我尝试通过远程桌面(从运行 Win XP Home 的 PC)运行该程序，则对 waveInGetNumDevs() 的调用将返回零。

作为替代方案，我从 RecordString() 函数中删除了对 waveInGetNumDevs()、waveInGetDevCaps() 和 waveInOpen() 的调用，而是在程序启动时只运行一次。 (对 waveInClose() 的调用也从 RecordString() 中删除。)现在，如果我在主机 PC 上启动程序，以便它成功调用 waveInOpen() 并检索到音频输入设备的句柄(HWAVEIN dev_handle)，然后我可以切换到通过远程桌面访问这台主机(当程序仍在运行时)，RecordString() 函数仍然可以正常工作。因此，一旦获得设备句柄，似乎可以通过远程桌面获得音频输入；问题是得到句柄。

有没有一种方法可以让我通过远程桌面运行整个应用程序，而不必在主机 PC 上本地启动它？

Answer 1

我找到了答案，感谢:http://www.wikihow.com/Hear-Audio-from-the-Remote-PC-when-Using-Remote-Desktop

启动远程桌面时单击“选项”按钮，然后选择“本地资源”选项卡，并确保“远程计算机声音”设置为“离开远程计算机”。

通过远程桌面运行时，问题中显示的原始代码现在可以正常工作。