importing soundcard blocks tkinter.filedialog.askdirectory on Windows

[johnohagan]

On Windows, the following code blocks after the print statement, unless the commented lines are uncommented:

from tkinter import filedialog
#import ctypes
#ctypes.windll.ole32.CoInitialize(None)
import soundcard

print('opening dialog')
filedialog.askdirectory()

I copied this solution from a 2018 Stack Exchange post. The workaround is pretty simple and doesn't seem to cause any issues, but it took forever to debug as the cause was far from obvious.

I don't pretend to understand the details (I'm generally a Linux user and came across this while porting something to Windows) but it's something to do with how Microsoft's COM handles threads. If the thread-handling state is set to multi-threaded, it's incompatible with that particular dialog widget (other tkinter dialogs work fine). It seems likely that soundcard is doing this - possibly at lines 41-49 of mediafoundation.py:

        if platform.win32_ver()[0] == '8':
            # On Windows 8, according to Microsoft, the first use of 
            # IAudioClient should be from the STA thread. Calls from 
            # an MTA thread may result in undefined behavior.
            
            # CoInitialize initialises calling thread to STA.
            hr = _ole32.CoInitialize(_ffi.NULL)
        else:
            hr = _ole32.CoInitializeEx(_ffi.NULL, COINIT_MULTITHREADED)

Maybe just calling _ole32.CoInitialize(_ffi.NULL) for all Windows versions would solve the problem? I don't know enough about this to know if that's a viable solution.

Thanks for your work on this module!

[bastibe]

Thank you for the bug report. I sadly don't know much about this either. If someone could step in who has a better understanding of the COM API, I'd be happy to accept pull requests.