Using Openh264 in a C# project

Question

I am trying to build a demo C# project using the openh264 library from Cisco.

I have a very basic setup. Here is the .sln file

Microsoft Visual Studio Solution File, Format Version 12.00
# Visual Studio Version 17
VisualStudioVersion = 17.0.31903.59
MinimumVisualStudioVersion = 10.0.40219.1
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "h264", "h264\h264.csproj", "{C9FA208E-5506-441B-9837-FB5469B950FA}"
EndProject
Global
        GlobalSection(SolutionConfigurationPlatforms) = preSolution
                Debug|x86 = Debug|x86
                Release|x86 = Release|x86
        EndGlobalSection
        GlobalSection(SolutionProperties) = preSolution
                HideSolutionNode = FALSE
        EndGlobalSection
        GlobalSection(ProjectConfigurationPlatforms) = postSolution
                {C9FA208E-5506-441B-9837-FB5469B950FA}.Debug|x86.ActiveCfg = Debug|x86
                {C9FA208E-5506-441B-9837-FB5469B950FA}.Debug|x86.Build.0 = Debug|x86
                {C9FA208E-5506-441B-9837-FB5469B950FA}.Release|x86.ActiveCfg = Release|x86
                {C9FA208E-5506-441B-9837-FB5469B950FA}.Release|x86.Build.0 = Release|x86
        EndGlobalSection
EndGlobal

The project file looks like this:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net7.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
      <Reference Include="openh264">
          <HintPath>openh264-2.3.1-win32.dll</HintPath>
      </Reference>
  </ItemGroup>

</Project>

While the Program.cs file looks like this:

using System.Runtime.InteropServices;

public class h264Demo {
    [DllImport("openh264-2.3.1-win32.dll", CallingConvention = CallingConvention.Cdecl)]
    public static extern int WelsCreateSVCEncoder();

    public static void Main() {
        Console.WriteLine("Hello h264 demo");
        int result = WelsCreateSVCEncoder();
        Console.WriteLine("Result is: {0}",result);
    }
}

It is what I could find using the dumpbin utility.

C:\Users\Admin\source\repos\h264Demo\h264>dumpbin /exports openh264-2.3.1-win32.dll
Microsoft (R) COFF/PE Dumper Version 14.33.31630.0
Copyright (C) Microsoft Corporation.  All rights reserved.


Dump of file openh264-2.3.1-win32.dll

File Type: DLL

  Section contains the following exports for openh264.dll

    00000000 characteristics
    FFFFFFFF time date stamp
        0.00 version
           1 ordinal base
           6 number of functions
           6 number of names

    ordinal hint RVA      name

          1    0 0007DDD0 WelsCreateDecoder
          2    1 00049D60 WelsCreateSVCEncoder
          3    2 0007DE20 WelsDestroyDecoder
          4    3 00049DA0 WelsDestroySVCEncoder
          5    4 00049DC0 WelsGetCodecVersion
          6    5 00049DC0 WelsGetCodecVersionEx

  Summary

        2000 .data
       1B000 .rdata
        4000 .reloc
        2000 .rodata
        1000 .rsrc
       A1000 .text

When I build I get the following warnings:

C:\Program Files\dotnet\sdk\7.0.102\Microsoft.Common.CurrentVersion.targets(2352,5): warning MSB3246: Resolved file has a bad image, no metadata, or is otherwise inaccessible. System.BadImageFormatException: PE image does not have metadata. [C:\Users\Admin\source\repos\h264Demo\h264\h264.csproj]
C:\Program Files\dotnet\sdk\7.0.102\Microsoft.Common.CurrentVersion.targets(2352,5): warning MSB3246: at System.Reflection.Metadata.MetadataReader.GetAssemblyName(String assemblyFile) [C:\Users\Admin\source\repos\h264Demo\h264\h264.csproj]
C:\Program Files\dotnet\sdk\7.0.102\Microsoft.Common.CurrentVersion.targets(2352,5): warning MSB3246: at Microsoft.Build.Shared.AssemblyNameExtension.GetAssemblyNameEx(String path) [C:\Users\Admin\source\repos\h264Demo\h264\h264.csproj]
C:\Program Files\dotnet\sdk\7.0.102\Microsoft.Common.CurrentVersion.targets(2352,5): warning MSB3246: at Microsoft.Build.Tasks.SystemState.GetAssemblyName(String path) [C:\Users\Admin\source\repos\h264Demo\h264\h264.csproj]
C:\Program Files\dotnet\sdk\7.0.102\Microsoft.Common.CurrentVersion.targets(2352,5): warning MSB3246: at Microsoft.Build.Tasks.ReferenceTable.SetPrimaryAssemblyReferenceItem(ITaskItem referenceAssemblyName) [C:\Users\Admin\source\repos\h264Demo\h264\h264.csproj]

subsequently when I execute the resulted executable I receive:

$ ./h264.exe
Hello h264 demo
Fatal error. 0xC0000005
   at h264Demo.WelsCreateSVCEncoder()
   at h264Demo.Main()
Segmentation fault

When I tried the Openh264Lib.net project suggested here I could use the library.

However I cannot understand why my solution does not work. The openh264 binaries are the official ones.

may be digging deeper with settting log level higher? e.g. `dotnet build /flp:v=diag` — Falco Alexander, Apr 03 '23 at 20:57
It does not say anything. ``` Resolved file path is "C:\Users\Admin\source\repos\h264Demo\h264\openh264-2.3.1-win32.dll". Reference found at search path location "{HintPathFromItem}". For SearchPath "{CandidateAssemblyFiles}". Considered "openh264-2.3.1-win32.dll", but its name "openh264-2.3.1-win32" didn't match the expected name "openh264". Considered "openh264-2.3.1-win64.dll", but its name "openh264-2.3.1-win64" didn't match the expected name "openh264". ``` — msmechanized, Apr 03 '23 at 21:08
I running on windows. Under git bash. Here is the message that I get ` Hello h264 demo Fatal error. 0xC0000005 at h264Demo.WelsCreateSVCEncoder() at h264Demo.Main() ` same without segfault when I run under CMD. — msmechanized, Apr 03 '23 at 21:22
Adding native library as reference doesn't make sens... Just copy dll to the output directory — Selvin, Apr 03 '23 at 21:39
The native .dll exists in the output directory. I don't get a dll not found error. — msmechanized, Apr 04 '23 at 04:39

Using Openh264 in a C# project

0 Answers0