Python script to convert .m4a files to .mp3 in bulk.
- Run 
python convert.pyin the folder with the.m4afiles you want converted - Wait
 - Converted 
.mp3files should be there when done 
- FFmpeg
 - Pydub: 
pip install pydub 
Tested to work with .webm also; just replace the extension on lines 5 and 6.
In theory it should also work with any other file type Pydub/FFmpeg allows:
| Format | Extensions | Notes | 
|---|---|---|
| WAV | .wav | 
Supported natively (no FFmpeg required) | 
| MP3 | .mp3 | 
Requires FFmpeg | 
| AAC | .aac, .m4a | 
Requires FFmpeg | 
| OGG | .ogg, .oga | 
Requires FFmpeg | 
| FLAC | .flac | 
Requires FFmpeg | 
| AIFF | .aiff, .aif | 
Requires FFmpeg | 
| MP4 Audio | .mp4, .m4a | 
Requires FFmpeg | 
| WMA | .wma | 
Requires FFmpeg | 
| AMR | .amr | 
Requires FFmpeg | 
| WebM | .webm | 
Requires FFmpeg | 
| 3GP Audio | .3gp | 
Requires FFmpeg |