How to make screen capture video using Direct Show.net Library?

Question

How to make screen capture video using Direct Show.net Library? I read msdn Direct show document and find the way to change video source device within the following code. This code got webcamera as video device.

   public IBaseFilter FindCaptureDevice()
{
  int hr = 0;
  IEnumMoniker classEnum = null;
  IMoniker[] moniker = new IMoniker[1];
  object source = null;
  // Create the system device enumerator
  ICreateDevEnum devEnum = (ICreateDevEnum) new CreateDevEnum();

  // Create an enumerator for the video capture devices
  hr = devEnum.CreateClassEnumerator(FilterCategory.VideoInputDevice, out classEnum,0);
  DsError.ThrowExceptionForHR(hr);

  // The device enumerator is no more needed
  Marshal.ReleaseComObject(devEnum);

  // If there are no enumerators for the requested type, then 
  // CreateClassEnumerator will succeed, but classEnum will be NULL.
  if (classEnum == null)
  {
    throw new ApplicationException("No video capture device was detected.\r\n\r\n" +
                                   "This sample requires a video capture device, such as a USB WebCam,\r\n" +
                                   "to be installed and working properly.  The sample will now close.");
  }




  if (classEnum.Next (moniker.Length, moniker, IntPtr.Zero) == 0)

  {

    Guid iid = typeof(IBaseFilter).GUID;
    moniker[0].BindToObject(null, null, ref iid, out source);
  }
  else
  {
    throw new ApplicationException("Unable to access video capture device!");   
  }


  Marshal.ReleaseComObject(moniker[0]);
  Marshal.ReleaseComObject(classEnum);


  return (IBaseFilter) source;
}

Answer 1

You need a filter which captures screen and sends the video down the stream. In DirectShow SDK there is a sample filter called PushSource and inside there is PushSourceDesktop. Compile it and insert into your graph as a source filter.