"Class not registered" when loading the Video Processor MFT on Windows 7

1

I have the following COM call:

IMFTransform* pMFT = NULL;
HRESULT hr = CoCreateInstance(CLSID_VideoProcessorMFT, NULL, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&pMFT));

On my development machine, this call to CoCreateInstance succeeds. However, when I deploy this on my old Windows 7 machine, the call to CoCreateInstance fails, and I don't know why. Here's how I'm displaying the error:

_com_error err(hr);
LPCTSTR hrErrMsg = err.ErrorMessage();
WCHAR msg[MAX_PATH];
StringCbPrintf(msg, sizeof(msg), L"HRESULT=0x%X, %s", errContext, hrErr, hrErrMsg);
MessageBox(hwnd, msg, L"Error", MB_ICONERROR);

And here's the error I get in that message box:

HRESULT=0x80040154, Class not registered

That is, the COM class for the Video Processor MFT is not registered. I see that CLSID_VideoProcessorMFT is defined as:

EXTERN_GUID(CLSID_VideoProcessorMFT, 0x88753b26, 0x5b24, 0x49bd, 0xb2, 0xe7, 0xc, 0x44, 0x5c, 0x78, 0xc9, 0x82);

This is the GUID 88753B26-5B24-49bd-B2E7-0C445C78C982 in disguise. I understand that COM classes are registered in the Windows Registry with a key containing this GUID. Using Registry Editor on my developer machine, I can see the key:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{88753B26-5B24-49bd-B2E7-0C445C78C982}

and this key has a "Default" value of %SystemRoot%\System32\msvproc.dll, referring to the filepath C:\Windows\System32\msvproc.dll, which does exist.

On my old Windows 7 machine, this key in the registry does not exist -- as expected, given the "Class not registered" error. And there is no file at C:\Windows\System32\msvproc.dll. But this is where the trail goes cold. I don't know what is supposed to register that class in the registry, and why it hasn't run on my old Windows 7 machine.

Possible conclusions:

  • I have to register the Video Processor MFT myself. However, the docs do not suggest this, and I don't know how I would do it.
  • Windows 7 does not support the Video Processor MFT. But the docs provide no indication of this. Indeed, they say "Media Foundation requires Windows Vista or later", which should include my Windows 7 machine.
  • I'm loading the Video Processor MFT in the wrong way. Is there a more system-independent way to load it?

Which of these is the right conclusion? Is it possible to load the Video Processor MFT on Windows 7? If so, how?

winapi
dll
com
windows-7
ms-media-foundation
asked on Stack Overflow Apr 10, 2020 by jameshfisher

2 Answers

1

Even though even older documentation for Video Processor MFT does not mention availability restrictions, they can still be assumed from related content:

Requirements

Minimum supported client: Windows 8 Release Preview

Minimum supported server: Windows Server 2012

Applications that target earlier versions of Windows are likely to be supposed to use other DSPs like Color Control Transform DSP and Color Converter DSP. These were/are not GPU accelerated though.

The advantage of Video Processor MFT was that it supported GPU-accelerated video processing using Microsoft Direct3D 11.

answered on Stack Overflow Apr 10, 2020 by Roman R. • edited Apr 10, 2020 by Roman R.
0

(This is an expansion on @SimonMourier's very helpful comment, for future readers, since it was all new to me.)

I believe CLSID_VideoProcessorMFT is available as follows:

  • For "Windows Desktop Applications" on >= Windows 8.1
  • For "Windows Store Applications" on >= Windows 10
  • For "Windows Phone Applications" on >= Windows 10

The header file mfidl.h documents which Windows version a specific COM class was introduced in. Following CLSID_VideoProcessorMFT to its definition, I find:

#if (WINVER >= _WIN32_WINNT_WINTHRESHOLD) 
#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP)
// ...
EXTERN_GUID(CLSID_VideoProcessorMFT, 0x88753b26, 0x5b24, 0x49bd, 0xb2, 0xe7, 0xc, 0x44, 0x5c, 0x78, 0xc9, 0x82);
#endif /* WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP) */
#endif // (WINVER >= _WIN32_WINNT_WINTHRESHOLD) 
// ...
#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)
#if (WINVER >= _WIN32_WINNT_WINBLUE) 
#if (WINVER < _WIN32_WINNT_WINTHRESHOLD) 
EXTERN_GUID(CLSID_VideoProcessorMFT, 0x88753b26, 0x5b24, 0x49bd, 0xb2, 0xe7, 0xc, 0x44, 0x5c, 0x78, 0xc9, 0x82);
#endif // (WINVER < _WIN32_WINNT_WINTHRESHOLD) 
#endif // (WINVER >= _WIN32_WINNT_WINBLUE) 
// ...
#endif /* WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP) */

By following and decoding all these macros, I got the availability list above.

answered on Stack Overflow Apr 10, 2020 by jameshfisher

User contributions licensed under CC BY-SA 3.0