mkl==2020.0 breaks loading openH264 library

[JackCaster]

Expected behaviour

OpenCV can load openh264-1.8.0-win64.dll

Actual bejaviour

OpenCV cannot load openh264-1.8.0-win64.dll

Steps to reproduce

Create a new conda environment with the following

name: test_opencv

channels:
 - defaults

dependencies:
- python
- mkl==2020.0
- numpy
- pip
- pip:
   - opencv-contrib-python

and run the following code:

import cv2

fourcc = cv2.VideoWriter_fourcc(*'X264')
out = cv2.VideoWriter('output.avi',fourcc, 20.0, (640,480))

By conda installing mkl==2020.0 opencv cannot load openh264-1.8.0-win64.dll. The following error appears:

...
Failed to load OpenH264 library: openh264-1.8.0-win64.dll
        Please check environment and/or download library: https://github.com/cisco/openh264/releases
...

Instead, installing mkl==2019.* via conda the openH264 is loaded successfully:

...
OpenH264 Video Codec provided by Cisco Systems, Inc.
...

• operating system: Windows 10
• architecture (e.g. x86): amd64
• opencv-python version: pip install opencv-contrib-python-4.2.0.34

[skvark]

I can't provide support for additional external dependencies which you have installed via conda. By the looks of it this seems to be some packaging / versioning problem related to the mkl library since the earlier version works.

[JackCaster]

I see. I will open the issue in the mkl repository. Thanks anyway!