brukshut/m4atool

Python utility for manipulating apple lossless metadata.

m4atool

m4atool.py is a python utility for manipulating Apple Lossless files. This utility is intended to facilitate the bulk modification of Lossless files with an *m4a extension. Although proprietary, the Apple Lossless format has been reversed engineered. See https://mutagen.readthedocs.io/en/latest/api/mp4.html?highlight=mp4#module-mutagen.mp4.

Setup

Create a virtual environment and install required packages.

user% python -m venv venv
user% source venv/bin/activate
user% pip install -r requirements.txt
user% pip install .

Usage

user% m4atool
usage: m4atool [-h] [--basedir BASEDIR] [--debug] [--filename FILENAME] [--rename] [--sanitize] [--album ALBUM] [--artist ARTIST]
               [--genre GENRE]
m4atool: error: Please specify --basedir or --filename.

Functionality

• It requires either a base directory argument or a filename argument.
• If a directory argument is given, the directory is recursed producing a list of m4a files.
• It allows sanitizing of album, album artist, artist, genre and track title tags tags, ensuring that they follow a consistent format that avoids certain characters.
• It permits bulk updating of album, artist, and genre tags.
• It renames files using a preferred format that is composed of several existing tags.

Sanitizing Tags

The tags for album, album artist, artist, genre and track titles are sanitized using the following rules.

• All strings in tags are capitalized, so How Low Can a punk Get? becomes How Low Can A Punk Get?
• All square brackets in tags are converted to parentheses.
• All backslash characters are converted to --.
• All single dashes with whitespace padding are converted to --.

Renaming Files

• The utility will extract tags from the Lossless file and use them to construct a new file name.
• The default format is 01 {artist} - {track_title}.m4a with the first field a zero padded track number.
• The utility will rename the file 01 Checkmate.m4a to 01 Hot Snakes - Checkmate.m4a.
• The tags will be sanitized first using the rules mentioned above, thus 18 How Low can a Punk get? [studio take].m4a is renamed to 18 Bad Brains - How Low Can A Punk Get? (Studio Take).m4a.

Bulk Tag Updates

• The album, artist, and genre tags can be overridden and updated on all files.

Testing

There are unittests for M4a class in the tests directory.

(venv) user% cd tests/
(venv) user% ls
(venv) user% python -m unittest test_m4a.py