Writing an iTunes playlist generator in Python

24 Jul 2007

The following is some quick & dirty code on how one might approach the idea of writing a playlist generator in Python.

The language almost doesn’t matter but ActivePython does ship with bindings that allow you easily interact with any Windows COM object. It worked nicely in conjunction with iTunes Windows SDK.

In the end it’s fairly trivial code hacked together in not much more than an hour or so but I’ve been quite happy with the playlists it creates.

Basic Design:

1) Provide a means for the caller to specify basic criteria for playlist generation. ie) # of songs, list of genre’s, propotion of songs per genre, etc.

2) Retrieve a list of songs on an iPod and their metadata relevant to generation (name, genre, play count, etc.).

3) Implement a simple algorithm to choose the appropriate # of songs from each genre as per the original criteria.

4) Create the playlist in iTunes

Code: (this was actually part of my last hack day project, so excuse the python inadequacies)

#!/usr/bin/env python

import pythoncom, win32com.client, time
import sys, os
import csv
from random import Random, shuffle

SOURCE_ID = "Adam's iPod"
EXPORT_FILE = "ipod.data"
CRITERIA = {"name":"Test Playlist", 
            "count":25, 
            "genres":{"Alternative":.15, "Other":.25, "Rock":.60}, 
             "minPlayCount":5}

def main():
    print 'attaching to iTunes...'
    iTunes = win32com.client.gencache.EnsureDispatch("iTunes.Application")
    
    print 'connecting to ' + SOURCE_ID + '...'
    source = iTunes.Sources.ItemByName(SOURCE_ID)
    
    iPodTracks = source.Playlists.ItemByName("Music").Tracks
    libraryTracks = iTunes.LibraryPlaylist.Tracks
    
    name = CRITERIA["name"]
    count = CRITERIA["count"]
    minPlayCount = CRITERIA["minPlayCount"]
    genres = CRITERIA["genres"]

    print 'creating a playlist called "' + name + '" with ' + str(count) + ' songs'
    
    # Create a map of genre -> song where each song satisfies the minPlayCount criteria
    songsByGenre = {}
    for i in range(1, libraryTracks.Count):
        track = libraryTracks.Item(i)        
        if track.Genre in genres and track.PlayedCount > minPlayCount:
            tracks = songsByGenre.get(track.Genre, [])
            tracks.append(track)
            songsByGenre[track.Genre] = tracks

    # For each applicable genre, pull a quasi random set of tracks
    shuffle = Random(None).shuffle
    playlistTracks = []
    for genre in songsByGenre.keys():
        numSongs = int(round(genres[genre] * count))
        tracks = songsByGenre[genre]
        shuffle(tracks)
        print genre + ': ' + str(len(tracks[0:numSongs])) + ' songs'
        for track in tracks[0:numSongs]:
            playlistTracks.append(track)
            
    # Remove any pre-existing playlists that exist with the same name
    librarySource = iTunes.Sources.ItemByName("Library")
    for i in range(1, librarySource.Playlists.Count + 1):
        try:
            playlist = librarySource.Playlists.Item(i)
            playlist = win32com.client.CastTo(playlist, 'IITLibraryPlaylist')
            if playlist.Name == name:
                playlist.Delete()
        except:
            pass
        
    # Create the playlist and add the tracks.
    playlist = win32com.client.CastTo(iTunes.CreatePlaylist(name), 'IITLibraryPlaylist')    
    for track in playlistTracks:        
        playlist.AddTrack(track)
    
if __name__ == '__main__':
    main()