visual c++ virtual camera application doesn't work on 64-bit windows

Question

I am trying to implement a virtual camera application in Visual C++ for 64 bit Windows. I started with the code here: tmhare.mvps.org/downloads/vcam.zip which emulates a video capture device using DirectShow filters. It works fine for me on 32 bit windows, but doesn't work on 64 bit windows. I modified the Visual C++ project as follows:

1) changed the platform to x64 and recompiled the dll, linking in the 64-bit version of strmbase.lib
2) changed preprocessor definitions to WIN64,_WIN64 from WIN32,_WIN32;
3) Recompiled the library and registered the dll using C:\Windows\system32\regsvr32.exe 

The dll registers successfully and regedit shows three keys for my virtual camera in

HKEY_CLASSES_ROOT\CLSID\{860BB310-5D01-11D0-BD3B-00A0C911CE86}\Instance\{8E14549A-DB61-4309-AFA1-3578E927E933},
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{860BB310-5D01-11D0-BD3B-00A0C911CE86}\Instance\{8E14549A-DB61-4309-AFA1-3578E927E933},
HKEY_CLASSES_ROOT\CLSID\{8E14549A-DB61-4309-AFA1-3578E927E933}\InprocServer32

However, neither Skype nor Windows Live Messenger see the camera on 64-bit windows.
What am I doing wrong? I understand that Win64 has HKEY_LOCAL_MACHINE\Software\Classes\CLSID{guid} for 64-bit applications and HKEY_LOCAL_MACHINE\Software\Wow6432Node for 32-bit applications, but since I am compiling my code as a 64-bit application, it seems to me that its keys are being placed in the right part of the registry. Is there a DirectShow virtual camera filter implementation for 64-bit windows I could use as a sample (I only found one for 32-bit windows)?

Answer 1

I tried out DirectShow a year or so back, and from what I can remember, there isn't support for it in 64-bit applications. So I'd recommend either switching to 32-bit mode, or finding a library which supports 64-bit. This may help you.

http://directshownet.sourceforge.net/

Answer 2

64-bit filters work exactly as their 32-bit peers, no specificity involved. A general rule applies, which is worth mentioning: filter DLL bitness should match the application bitness, e.g. as Skype is always 32-bit regardless of OS bitness, you need 32-bit virtual camera for it. Skype just does not care about 64-bit filters as it never uses them.

Also, I don't understand your #2 above. You only need to create duplicate existing configuration for another target (x64) and visual Studio will update predefined conditionals such _WIN64, no manual changes required in code.