How to Decode and Convert Audio Files on Mac

Overall summary of the instructions

This guide provides a detailed process to decode and convert AAC (.m4a) audio files into WAV format on a Mac. It includes both graphical and command-line methods, leveraging tools like iTunes, VLC, and FFmpeg.

TLDR

Use iTunes for a graphical interface or FFmpeg for command-line conversion.

Step-by-step detailed guide

Using iTunes (Music App)

1. Open iTunes: Launch the iTunes application on your Mac.
2. Import Settings: Go to Preferences -> General -> Import Settings....
3. Select WAV Encoder: In the Import Using dropdown menu, choose WAV Encoder and click OK.
4. Convert AAC to WAV: Right-click on the AAC file and select Create WAV Version.
5. Revert Settings: Don’t forget to change the Import Using setting back to AAC if you prefer to use it for future imports.

Using VLC Media Player

1. Open VLC: Launch the VLC media player on your Mac.
2. Convert/Stream: Go to File -> Convert / Stream.
3. Add File: Drop your AAC (.m4a) file or click Open media... to browse and select the file.
4. Choose Profile: From the Choose Profile dropdown, select Custom. Click Customize and set the options under Encapsulation and Audio codec tabs to WAV.
5. Save to File: Click Apply, then Save as File to specify the output destination, and finally click Save to export the WAV file.

Using FFmpeg (Command-line)

1. Install FFmpeg: Install FFmpeg via Homebrew by running brew install ffmpeg in the terminal.
2. Convert Single File: Open the terminal and run the command: ffmpeg -i input.m4a output.wav.
3. Batch Conversion: For converting multiple files in a directory, use the following command:

   for f in *.m4a; do ffmpeg -i "$f" "${f/%m4a/wav}"; done
   

References

• How to decode AAC (.m4a) audio files into WAV? - Super User