Can't import cv2 : DLL is missing and so on

[AlainPaillou]

System Information

Hello,

as many people, i tried to compile opencv with some options (like Cuda, GStreamer, etc.).

My system :
Windows 11 laptop
Python 3.11.2
Visual studio 2022

I successfully compiled opencv 4.7.0 and 4.5.5 with Cuda and GStreamer.

BUT, when i try to import cv2, for sure, i get an issue : DLL is missing or things like that. I saw topics about that kind of errors. It seems they are quite common. As for me, i give up, after trying many things with always the same result : epic fail.

I would like to say that it is really boring to spend so many time waiting for compilation result and seeing the issue when importing cv2.

I DO like opencv but it is really strange to have to compile opencv for very common extension like Cuda or GSttreamer. And of course, it is also more strange to spend hour in order to always get an issue. Really boring.

So, i have uninstalled everything (so i won't be able to reproduce the issue) and i use very standard opencv version without GPU acceleration and with crappy video encode. Too bad.

Please, try to make something more usable and more user friendly.

Many thanks in advance.

Alain

Detailed description

Can't import cv2

Steps to reproduce

Just compile opencv with Cuda & GStreamer and to to import cv2 with Python 3.11

You will get the issue.

Issue submission checklist

• I report the issue, it's not a question
• I checked the problem with documentation, FAQ, open issues, forum.opencv.org, Stack Overflow, etc and have not found any solution
• I updated to the latest OpenCV version and the issue is still there
• There is reproducer code and related data files (videos, images, onnx, etc)

[cudawarped]

BUT, when i try to import cv2, for sure, i get an issue : DLL is missing or things like that. I saw topics about that kind of errors. It seems they are quite common. As for me, i give up, after trying many things with always the same result : epic fail.

Did you try the solution outlined here to track down the missing dll[s]?

So, i have uninstalled everything (so i won't be able to reproduce the issue) and i use very standard opencv version without GPU acceleration and with crappy video encode. Too bad.

If you have CUDA 12.0 then you could try a pre-built wheel from here .

[AlainPaillou]

I solved the missing DLL but I had an other issue and so on and so on. But thx for the advise.

I will upgrade CUDA to 12.0 version and I will try the pre build wheel ASAP. Thx !

But it is to bad to get such difficulties to use opencv with interesting extensions !

[AlainPaillou]

I started from zero one more time with OpenCV 4.7.0 & CUDA & GStreamer. Compiled and builded without problem.

I still have the DLL issue. I tried everything, adding paths and DLL everywhere. No way, it does not work.

This opencv installation is ridiculous. What a waste of time.

I did not try the pre build wheel because for my program, i also need GStreamer (for Cuda, i use pycuda and opencv with cuda is a bit useless for me).

I can only install opencv with :
py -m pip install opencv-python

or

py - m pip install opencv_python-XXXXXXX.whl

Everything else won't work. I can't understand this situation. This time, i give up. I will search other libraries and i will forget opencv.

Opencv sucks.

Bye.

[mshabunin]

Python on Windows requires more effort to load DLLs since 3.8 (https://docs.python.org/3/whatsnew/3.8.html#bpo-36085-whatsnew). In particular one have to add each DLL location using os.add_dll_directory in addition to adding them to PATH. Both CUDA and GStreamer are quite complex dependencies and might have multiple layers underneath. OpenCV can not detect locations of all third-party dependencies and their dependencies and so on. I can recommend using Python from conda-forge instead of official Python binaries, AFAIK reverts new DLL search mechanism.

[cudawarped]

I started from zero one more time with OpenCV 4.7.0 & CUDA & GStreamer. Compiled and builded without problem.

I still have the DLL issue. I tried everything, adding paths and DLL everywhere. No way, it does not work.

That's interesting. So after you identified the missing dll's with Process Monitor and added them with os.add_dll_diretory what error where you getting? I'm asking because it can't have been the same error if Process Monitor didn't show any output where python was trying to CreateFile with a Name Not Found Error, and as I wrote the short guide I linked to to help people with this exact problem I would like to know what I can add to it?

[AlainPaillou]

Hi cudawarped,

i used Process Monitor to see which DLL are missing, i added path with os.add_dll_directory and i also added path in Windows system path. Epic fail. I lost 3 more hours with this problem.

As i said, i give up with opencv. It used to be interesting. I will focus my effort with new libraries like Cupy / Arrayfire (ok, it's a bit different but there are interesting) and Pytorch for example.

mshabunin : tks for the advise. Maybe i will try to use Python from conda-forge but i am not sure i will. It may solve some issues but it will probably generate new issues.

[LaurentBerger]

@cudawarped

I use this configuration in procmon

It is possible to save configuration in procmon. It's a pmc file but I don't know if it can be shared safetly

ProcmonConfiguration.zip