b-k / ludwig_van_shuffle

Produce shuffled playlists that preserve the order of multi-movement pieces

Overview

Ludwig van Shuffle will generate a shuffled track listing, while retaining multi-movement pieces as a unit. You can specify your favorite pieces so they are put on the playlist more often.

Here is a sample output from my music directory. Each line is a single filename for a single mp3/m4a/ogg, which is a common playlist format handled by most music players as an .m3u file. A quick skim shows three blocks of multi-track pieces shuffled in with everything else.

Budos_Band/2007-Budos_Band/05-Monkey_See,_Monkey_Do.mp3
various/SXSW_2014_Showcasing_Artists_Part1/Boldy_James-Moochie.mp3
Witold_Lutosławski/2015-Piano_Concerto,_Symphony_No._2/01-Concerto_for_Piano_and_Orchestra_-__1_♩._=_ca._110.mp3
Witold_Lutosławski/2015-Piano_Concerto,_Symphony_No._2/02-Concerto_for_Piano_and_Orchestra_-__2_Presto_-_Poco_meno_mosso_-_Lento.mp3
Witold_Lutosławski/2015-Piano_Concerto,_Symphony_No._2/03-Concerto_for_Piano_and_Orchestra_-__3_♪_=_ca._85_-_Largo.mp3
Witold_Lutosławski/2015-Piano_Concerto,_Symphony_No._2/04-Concerto_for_Piano_and_Orchestra_-__4_♩_=_ca._84_-_Presto.mp3
Moon HoP/Welcome Back To The Moon/07_Mambo_Es_Ska.mp3
Björk_Guðmundsdóttir/1995-post/05_Enjoy.mp3
Remy_Zero/The_golden_hum/01-the_golden_hum.mp3
Remy_Zero/The_golden_hum/02-glorious_1.mp3
Remy_Zero/The_golden_hum/03-out_in.mp3
various/SXSW_2014_Showcasing_Artists_Part1/Ingrid_Michaelson-Girls_Chase_Boys.mp3
RuPaul/supermodel_of_the_world/03_Free_Your_Mind.mp3
Nields/gotta_get_over_greta/05-i_know_what_kind_of_love_this_is.mp3
Osvaldo_Golijov/2007-Oceana/08-Tenebrae_-__I_First_Movement.mp3
Osvaldo_Golijov/2007-Oceana/09-Tenebrae_-__II_Second_Movement.mp3
Ana_Tijoux/2009-1977/13-Avaricia.mp3
Leadbelly/Where_did_you_sleep_last_night.mp3
various/Jobim_songbook/06_Antonio_Carlos_Jobim___Só_Danço_Samba.mp3

Building set lists

Before building playlists, you will first have to provide set lists indicating which pieces should hold together. Ludwig van Shuffle uses plain text files because directory structures and the ID3v2 TSST tag are not as reliable, text files are easy to write, and once you have prepared one you will never have to think about it again.

In a directory with some multi-track portions, add a file named sets, where each line is of the form

track.mp3|set name

For example, here is a sample of a sets file for Yiddishbbuk (St Lawrence String Quartet + Osvaldo Golijov composer):

01-Last_Round_-__I_Movido,_urgente.mp3|last round
02-Last_Round_-__II_Lentissimo.mp3|last round
03-Lullaby_and_Doina_-__1_Lullaby.mp3
04-Lullaby_and_Doina_-__2_Doina.mp3
05-Lullaby_and_Doina_-__3_Gallop.mp3|
06-Yiddishbbuk_-__Ia._D.W._(1932-1944).mp3|yiddishbbuk
07-Yiddishbbuk_-__II_I.B.S._(1904-1991).mp3|yiddishbbuk
08-Yiddishbbuk_-__III_L.B._(1918-1990).mp3|yiddishbbuk

The name can be anything—a, b, c or 1, 2, 3 are sufficient, just enough to uniquely identify the set within this directory. Note that tracks 3-5 are unlabelled in the example, because those are a loose set of songs that are OK to shuffle.

• Tracks 3 and 4 have no pipe at all, and track 5 has a pipe followed by nothing; either works.

• The script will prefix the path to the set list and use the full path for string comparisons, so begin the line with the bare directory name (not ./ or such).

• The easiest way to generate the file may be to write a directory listing to the sets file via ls > sets, then open sets in a text editor to add set names.

You can also a grand sets file in a higher directory, with subdirectories:

2007-Oceana/08-Tenebrae_-__I_First_Movement.mp3|tenebrae
2007-Oceana/09-Tenebrae_-__II_Second_Movement.mp3|tenebrae
2002-Yiddishbbuk/01-Last_Round_-__I_Movido,_urgente.mp3|last round
2002-Yiddishbbuk/02-Last_Round_-__II_Lentissimo.mp3|last round

• The find utility produces output that looks like this. Here is a pipeline to get a listing, then use a sed filter to remove the initial ./ and add a final |:

cd /path/to/music; find . -type f -name '*mp3' | sed 's-^./--' | sed 's/$/|/' | sort > sets

Running it

Once you have a sets file in every directory with a collection (meaning that many album directories may not need a sets file at all), go to the root of your collection and run

python make_playlist.py > list.m3u

This playlist should be ready to load into your favorite music player (sequentially, without the music player's less discerning shuffle feature). Typical music players look for an .m3u ending to the file name.

• The script writes to stdout, so you have the option to write to any file name or location you need, or to filter the output, such as modifying the path names to suit your music player's expectations or filtering out tracks by an artist you aren't in the mood for today.
• The playlist is generated from the directory you are running the script from, but you can also change the music_directory variable at the top of the script to a fixed location.
• The random number generator is seeded with the time, so you will get a newly-shuffled playlist on every run (as long as your runs are more than a second apart).

Weights

By default, all tracks are equally likely to be drawn—they each have a weight of one. You can build a score file to modify this. The scores file is separate from the sets file(s) under the presumption that it will change as your preferences change, whereas Beethoven's fifth symphony will always have four movements.

Each line is a pipe delimited list of the form

path/to/element|weight

where element is either a file or the name of a set, and weight is the new weight. Here is a sample score file with some weights set:

Björk_Guðmundsdóttir/1995-post/05_Enjoy.mp3|2
2007-Oceana/tenebrae|2
2007-Oceana/last round|1.7
Ana_Tijoux/2009-1977/13-Avaricia.mp3|.6
Leadbelly/Where_did_you_sleep_last_night.mp3

• The first two items are each now twice as likely to be drawn. A weight of less than one lowers the chance that an element is picked.
• For sets, instead of a file name use the label for the set, as with tenebrae and last round as defined in the sets list above.
• The same rules apply as for the sets lists: lines with no pipe or a pipe followed by nothing are ignored, as in the last line of the above example, and paths are relative to the current directory or the music_directory you set at the top of the script, and should not have any initial ./ or /.
• By default, the file should be named scores, in the music_directory, but set it as you prefer at the top of the script. If the file is not found, then no weights are changed.

Once Ludwig puts a track on a new playlist, it will not appear again, no matter how much weight it had. If you set list_length at the top of the script to a number larger than the number of elements you have, every track will be put on the list exactly once, but higher-weighted tracks are likely to appear higher in the set list. If you want a favorite track to appear multiple times in a playlist, concatenate together a number of short lists.