This setting only works with Audacity 3.0.0 - I test it and it doesn't work with the new version
- Close your Audacity app, if it is open
- Download the FFmpeg for windows from https://lame.buanzo.org/#lamewindl
- The file name is ffmpeg-win-2.2.2.exe
- Execute the file and follow the instructions
- Open Audacity App > go to "Edit" > Select "Preference"
- Click "Libraries" > Under "FFmpeg Library" to check if it is installed. It should look like this
Now just drop your mp4 to your Audacity and they will be imported to the app > then just export them as mp3 and Voila - DONE!