Honestly, what i understand from you question is that you may be running into trouble using Lame may be through subprocess for the bitrate conversion.

I have not tried that, but what i was trying was to convert the WAV format into MP3 while avoiding the FFMPEG which is quite bulky to be bundled with executable through pyinstaller.

So, i was looking for "libmp3lame.dll" to work with 64 bit python and it was not working becasue of some ctype issues and pretty old version of the Lame DLL.

Then I came across lameenc 1.8.1 available at https://pypi.org/project/lameenc/ which did the trick for me.

It is also self contained so I do not need to bundle any additional dll file in my executable built with pyInstaller.

Please give it a try.