OpenCVSharp Version 4 depends on mfplat.dll

[grisharav]

Summary of your issue

When deploying our application that was upgraded to latest OpenCVSharp all worked fine in desktop environment, but when I tried to use OpenCVSharp 4.0.0 on Win 2012 R2 environment I got:

System.TypeInitializationException : The type initializer for 'OpenCvSharp.NativeMethods' threw an exception.
---- System.DllNotFoundException : Unable to load DLL 'OpenCvSharpExtern' or one of its dependencies: The specified module could not be found. (Exception from HRESULT: 0x8007007E)
at OpenCvSharp.NativeMethods.core_Mat_new2(Int32 rows, Int32 cols, Int32 type)
at OpenCvSharp.Mat..ctor(Size size, MatType type) in C:\projects\opencvsharp\src\OpenCvSharp\Modules\core\Mat\Mat.cs:line 121

After some digging and running Procmon, I noticed that the code tries to load C:\Windows\System32\mfplat.dll

I installed Windows Server Essentials Media Pack (https://www.microsoft.com/en-us/download/details.aspx?id=40837), and got the dependency satisfied, but I believe the code should run in server environment since no device interaction is performed.

Environment

Windows Server 2012 R2

What did you do when you faced the problem?

Just run any code referencing OpenCVSharp on a server without mfplat.dll available.

[grisharav]

It actually seems that OpenCVSharp 3.4.4 has this issue as well, when 3.4.1 does not.

[shimat]

It may be because I built OpenCV with WITH_MSMF flag enabled. I will reconsider the flag in development of 4.0.1 or later. https://github.com/opencv/opencv/blob/7fb70e170154d064ef12d8fec61c0ae70812ce3d/CMakeLists.txt#L344

[luisgoncalves]

I had the same problem in an Azure Windows Server 2016 environment. We couldn't find a Media Pack for WS2016 and even if we could, I'd like to avoid configuring its installation in an Azure VMSS. Also, downgrading OpenCVSharp to 3.4.1 wasn't an option due to performance.

While we wait for a new release that fixes this problem, what we did was to create an internal NuGet package with the missing DLLs that we install alongside OpenCVSharp (we did this by trial and error and copied the DLLs from a Windows 10 machine). Here's the nuspec in case it helps someone else:

<?xml version="1.0"?>
<package >
  <metadata>
  (...)
  </metadata>
  <files>
    <file src="ksuser.dll" target="runtimes\win-x64\native" />
    <file src="mf.dll" target="runtimes\win-x64\native" />
    <file src="mfcore.dll" target="runtimes\win-x64\native" />
    <file src="mfplat.dll" target="runtimes\win-x64\native" />
    <file src="mfreadwrite.dll" target="runtimes\win-x64\native" />
    <file src="<package-name>.props" target="build\net" />
  </files>
</package>

And the props file:

<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
	<PropertyGroup>
		<NativeDlls>$(MSBuildThisFileDirectory)..\..\runtimes</NativeDlls>
	</PropertyGroup>
	<ItemGroup>
		<None Include="$(NativeDlls)\win-x64\native\ksuser.dll">
			<Link>dll\x64\ksuser.dll</Link>
			<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
		</None>
        <None Include="$(NativeDlls)\win-x64\native\mf.dll">
			<Link>dll\x64\mf.dll</Link>
			<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
		</None>
		<None Include="$(NativeDlls)\win-x64\native\mfcore.dll">
			<Link>dll\x64\mfcore.dll</Link>
			<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
		</None>
		<None Include="$(NativeDlls)\win-x64\native\mfplat.dll">
			<Link>dll\x64\mfplat.dll</Link>
			<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
		</None>
		<None Include="$(NativeDlls)\win-x64\native\mfreadwrite.dll">
			<Link>dll\x64\mfreadwrite.dll</Link>
			<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
		</None>
	</ItemGroup>
</Project>

[grisharav]

Thanks, when can we expect 4.0.1 release?

[shimat]

Thank you for waiting https://www.nuget.org/packages/OpenCvSharp4/4.0.1.20190326

Hi, I see the dependency upon mfplat.dll is back again on newer versions of the library (4.4, 4.5). Is this intentional?