Delay-loading a C libary in C++ code

Question

I'm currently trying to load the ffmpeg library (in C) into my C++ project. The library consists of headers, .lib files and .dll files, all of which I loaded and used successfully. However, it is strongly desirable for our project to have these dll files loaded in delayed, and this is where I'm failing.

What it boils down to is this:

When I build the project without referring to any of the library's dll functions, it runs correctly and I see (by my logs) that all dlls are correctly loaded where I'm explicitly getting their DLL handle.
When I build the project and include function calls to the dll, the executable simple fails to load because it's missing 'xx.dll'. This is before the function call is done. IE: Simply by having a dll function call in my code, it seems the program tries to load it when starting.
- When I manually add the dlls next to my program's executable, it runs fine in both scenarios, but it is not desirable to have them next to my executable.

Is there something obvious that I'm missing or doing wrong?

Thanks!

Dont include your libs in your project just LoadLibrary() your dll whenever required. Also there is a flag /DELAYLOAD in VC++. — Mandar, May 09 '18 at 13:40
I'm not sure if /DELAYLOAD can be used if the DLL in question is outside your executable's folder. But then I've never tried. — Paul Sanders, May 09 '18 at 13:47
You cannot call a function from a DLL without having that DLL somewhere, preferably at a place where it can be found. What are your requirements? — n. m. could be an AI, May 09 '18 at 15:34
@mozfox I tried this, but it tells me there's an unresolved symbol (the library function I'm calling) — Bas in het Veld, May 09 '18 at 15:39
@n.m. I want to delay load it. So I'm manually loading it from code before it's used. — Bas in het Veld, May 09 '18 at 15:39
If you want to load it with LoadLibrary, you need to use GetProcAddress to get functions you want to call, rather than using function names directly in the code. And you should *not* link against the .dll or its .lib. — n. m. could be an AI, May 09 '18 at 15:50
Figured it all out, thanks for the feedback! I ended up removing the lib files and only loading the DLLs, and calling them using GetProcAddress, not the header files. — Bas in het Veld, May 11 '18 at 14:12

Delay-loading a C libary in C++ code

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