I need to maintain a project that uses OpenCV 3.0 for its main processing and based on QT. The development environment is based around QT Creator on Windows 10 and Visual C++ 2013 64-bit is used for building.
We want to make our app compatible with Windows 7, and there is an issue with this OS specifically. It is impossible to get video files to load, the same video files getting to load without issues when running the application on Windows 10 and 8. After investigation, this seems to be related to the ffmpeg DLL (opencv_ffmpeg300_64.dll). Using the Process Explorer tool from MS, I can notice that the mentioned DLL is loaded at the time a video file is opened (VideoCapture::open call) on Windows 10 and 8. On Windows 7, the DLL is never loaded, there is no trace of it in Process Explorer, and VideoCapture::isOpened obviously returns false with the same video files. The DLL is present in the same directory as the application executable.
Note : I run a standalone, release build of our app on Windows 7 for testing. The development environment is on Windows 10 only. Do you have any clue about a specific restriction or loading process of DLL loading on Windows 7? Would rolling out my own build of OpenCV address the issue?