Trouble Importing DLL Module in Python

You've encountered an issue when attempting to import the 'libuvc.dll' module in Python on Windows 10. Despite successfully compiling and importing the library using the same Python version on Linux, you now face difficulties on Windows.

The error you're encountering suggests that Python is unable to locate the 'libuvc.dll' module at the path retrieved by 'ctypes.util.find_library('libuvc')'. However, you've verified the existence of the file at that location.

The culprit lies in the 'cdll.LoadLibrary' function. In Python versions prior to 3.8, the 'winmode' parameter did not exist, and 'mode' was used directly. The default value of 'mode' was 'ctypes.DEFAULT_MODE', which corresponds to zero.

However, in Python 3.8 and later, the 'winmode' parameter was introduced to specify the DLL search mode. By default, it is set to 'None', which corresponds to 'nt._LOAD_LIBRARY_SEARCH_DEFAULT_DIRS'. Unfortunately, this search mode ignores modifications to 'os.environ['PATH'], sys.path', and 'os.add_dll_directory'.

Solution:

To resolve this issue, explicitly set the 'winmode' parameter to zero in the 'LoadLibrary' function. This will force Python to use the full path and successfully import the module.

import ctypes
name = ctypes.util.find_library('libuvc')
lib = ctypes.cdll.LoadLibrary(name, winmode=0)

By specifying 'winmode=0', you bypass the default search mode and ensure that Python loads the DLL from the expected location.