VC++, Win32: Setting VLC_PLUGIN_PATH programmatically

[eli13]

Hello.

(Another) question about VLC_PLUGIN_PATH:

It seems to me that it is not possible to set this variable on a Win32 System programmatically in a way that it can be used by libVlc: If I set up VLC_PLUGIN_PATH as an environment variable using control-panel -> Advanced -> Environment variables -> etc.. things work fine with libVLC (Defining it to something like C:\myplugins)

If I set them from within my program before calling new_libvlc for the first time, the variable is set within my program, but not within the process/thread where VLC runs. For example the following will not work:

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wstring vlcPluginDirectory = L"C:\\myplugins"; ::SetEnvironmentVariable(L"VLC_PLUGIN_PATH", vlcPluginDirectory.c_str()); m_pVlcInstance = libvlc_new(0, NULL);

All this makes sense as libVLc probably does not use the CreateProcess function of the win32 api and therefore the thread does not inherit the environment, but gets a new one.

Is there any known work-around simpler than the one mentioned here: http://permalink.gmane.org/gmane.comp.v ... evel/86757? I'm not so happy with having a folder named 'plugin' (VlcPlugins would be nice ) or having to modify the environment. Or do I get things totally wrong?

[Rémi Denis-Courmont]

All this makes sense as libVLc probably does not use the CreateProcess function of the win32 api and therefore the thread does not inherit the environment, but gets a new one.

The environment is process-wide state, not thread state. If the environment variable is set before libvlc starts, it just works. In fact, development builds of vlc.exe use VLC_PLUGIN_PATH:

http://git.videolan.org/?p=vlc.git;a=bl ... 0-git#l122

[eli13]

What do you exactly mean with "before libvlc starts"? I assumed that libvlc will "start" on the first call to libvlc_new(..) but setting the environment var before the first call to libvlc_new(..) does not work here (Win7, VC++ 2008, libVlc 2.0.1). Thanks for the help.

[Rémi Denis-Courmont]

As you can see in the code linked above, before the first call to libvlc_new() (within the address space).

[eli13]

Thanks again Rémi for the quick answer. I still can't get it to work. What is confusing me: From the source-linked above, I would assume this very simple program would work (If the directory C:\vlcPlugins is existing):

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#include "stdafx.h" #include "vlc/libvlc.h" #include <Windows.h> #include <iostream> int _tmain(int argc, _TCHAR* argv[]) { // ::SetEnvironmentVariable(L"VLC_PLUGIN_PATH", L"C:\\vlcPlugins"); // _putenv("VLC_PLUGIN_PATH=C:\\vlcPlugins"); _wputenv(L"VLC_PLUGIN_PATH=C:\\vlcPlugins"); libvlc_instance_t* pVlc = NULL; pVlc = libvlc_new(0, NULL); if(!pVlc) { std::cout << "Failed"; return 1; } std::cout << "OK"; return 0; }

But when I try to run it, I get:

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D:\Dev\PluginTestApp\Debug>PluginTestApp.exe [00802818] main libvlc error: No plugins found! Check your VLC installation. Failed

(It doesnt matter if I use SetEnvironmentVariable, _putenv, _wputenv)

But, when I manually set the environment variable before launching the exe, things work fine:

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D:\Dev\PluginTestApp\Debug>set VLC_PLUGIN_PATH=C:\vlcPlugins D:\Dev\PluginTestApp\Debug>PluginTestApp.exe OK

Glad for any hints pointing me to the place where I make a mistake.

[Rémi Denis-Courmont]

I don't know. Be sure to use the same CRT as libvlc.dll; that's known to cause various problems on Windows.

[eli13]

I think I have the correct ones: Dependency Walker tells me libvlc.dll uses MSVCRT.DLL what would be the Multithreaded, dynamic link /MD Version, the same that I use from within Visual Studio - strange.

For linking, I use the lib from http://code.google.com/p/vc-libvlc/ - should be correct according to some other post.

Well, its not such a big deal as there are lots of way to deal with this problem - I was just wondering if I'm missing something obvious.. And the rest is running perfect (until now).

Thanks for your help anyway.