What do nvldumdx.dll & nvd3dumx.dll do?

My application is doing weird stuff, but when
I trace and replay with apitrace, everything
looks just fine.

The only difference I can see is that apitrace
doesn’t load nvldumdx.dll or nvd3dumx.dll.

OS: Windows 7 & 10 64bit
Driver: tested with 390.65 -> 398.82
GPU: quadro 2000, nvs 5200, 1080 gtx

To clarify, my opengl application’s blending
doesn’t work when I start the application
normally(and those 2 dll’s are loaded), but
when I replay with apitrace(no evil dll’s) it
works just fine.

Also, the application works without a hitch
with an ati driver.

This is how the game looks with the 2 evil dll’s:

And this is the replay from apitrace with the background
being properly blended:

The DLLs that you’ve mentioned are DirectX DDI and OpenGL ICD drivers for NVIDIA’s chips. They are the interlayer that allows DirectX and OpenGL to use hardware acceleration, they wrap API calls and deliver these calls to GPUs through Windows kernel.
Unfortunately, I don’t know why the blending works incorrectly.

Thanks for the reply.

Why would those dll’s not be loaded in some situations then?
Like when I replay this specific trace with Apitrace for example.