Generate mp3 Playlists

Dumping a simple script here for posterity and if I need to revisit sometime. Just playing with a new device for playing music back. The interface for playing single song is fine, but an album of songs isn't great; it tends to play them in random-ish order rather than sorting according to either the file name or the meta data.

This is a bit frustrating, but luckily it does support playlists. Playlists, specifically m3u files, are not something I have needed in the past. Luckily the format is super simple, each line is the file name of a track and the tracks are played in the order they appear in the file.

Of course, I had to write a script to run through my music folder and generate one playlist per album where I have the music organized by artist then subfolders containing each individual album.

import os
import glob

music_folder = os.getcwd()
music_filter = '\*.mp3'

for (path, subdirs, files) in os.walk(music_folder):
os.chdir(path)
relative_path = path.replace(music_folder + '/', '').replace('/', '\\')
print(relative_path)

    if glob.glob(music_filter) != []:
        track_list = []
        for mp3_name in glob.glob(music_filter):
            track_list.append(relative_path + '\\' + mp3_name)

        filename = os.path.split(path)[1] + '.m3u'

        playlist = open(filename, 'w')
        for track in sorted(track_list):
            playlist.write(track + '\n')

        playlist.close()

os.chdir(music_folder)

Here I am writing the m3u file into the same directory as the mp3s but I am adding a relative path to each file because the player I am now using requires m3u files to be in the root and music to be in folders.

Update

I've been playing around with my specific mp3 player and noticed a few problems. The naming of each file with just the folder name doesn't help if the album could possibly belong to more than one artist. In the new version I prefix with the artist name for a better descriptive file name that makes it easier to distinguish when on the player itself. I also noticed that the player can use extended m3u file format so I added a tiny bit of metadata to the front of each file with the album and artist. The folder structure in place is artist\album so I just used the parts of the path for each folder get the album and artist, rather than reading specific mp3 tags from the files themselves.

import os
import glob

# BEWARE specific path mapped to the SD card mounted on my machine.
music_folder = '/Volumes/H2' #os.getcwd()
music_filter = '*.mp3'

for (path, subdirs, files) in os.walk(music_folder):
    os.chdir(path)
    relative_path = path.replace(music_folder + '/', '').replace('/', '\\')

    if glob.glob(music_filter) != []:
        track_list = []
        for mp3_name in glob.glob(music_filter):
            track_list.append(relative_path + '\\' + mp3_name)

        parts = os.path.split(path)
        artist = parts[0].split('/')[-1]
        album = parts[1]
        filename = artist.replace(' ', '_') + '_' + album.replace(' ', '_') + '.m3u'

        playlist = open(music_folder + '/' + filename, 'w')
        playlist.write('#EXTM3U\n')
        playlist.write('#EXTALB:' + album + '\n')
        playlist.write('#EXTART:' + artist + '\n')
        
        for track in sorted(track_list):
            playlist.write(track + '\n')

        playlist.close()

os.chdir(music_folder)