Calliope, slowly building steam

I wrote in December about Calliope, a small toolkit for building music recommendations. It can also be used for some automation tasks.

I added a bandcamp module which list albums in your Bandcamp collection. I sometimes buy albums and then don’t download them because maybe I forgot or I wasn’t at home when I bought it. So I want to compare my Bandcamp collection against my local music collection and check if something is missing. Here’s how I did it:

# Albums in your online collection that are missing from your local collection.

ONLINE_ALBUMS="cpe bandcamp --user ssssam collection"
LOCAL_ALBUMS="cpe tracker albums"
#LOCAL_ALBUMS="cpe beets albums"

cpe diff --scope=album <($ONLINE_ALBUMS | cpe musicbrainz resolve-ids -) <($LOCAL_ALBUMS) 

Like all things in Calliope this outputs a playlist as a JSON stream, in this case, a list of all the albums I need to download:

{
  "album": "Take Her Up To Monto",
  "bandcamp.album_id": 2723242634,
  "location": "https://roisinmurphy.bandcamp.com/album/take-her-up-to-monto",
  "creator": "Róisín Murphy",
  "bandcamp.artist_id": "423189696",
  "musicbrainz.artist_id": "4c56405d-ba8e-4283-99c3-1dc95bdd50e7",
  "musicbrainz.release_id": "0a79f6ee-1978-4a4e-878b-09dfe6eac3f5",
  "musicbrainz.release_group_id": "d94fb84a-2f38-4fbb-971d-895183744064"
}
{
  "album": "LA OLA INTERIOR Spanish Ambient & Acid Exoticism 1983-1990",
  "bandcamp.album_id": 3275122274,
  "location": "https://lesdisquesbongojoe.bandcamp.com/album/la-ola-interior-spanish-ambient-acid-exoticism-1983-1990",
  "creator": "Various Artists",
  "bandcamp.artist_id": "3856789729",
  "meta.warnings": [
    "musicbrainz: Unable to find release on musicbrainz"
  ]
}

There are some interesting complexities to this, and in 12 hours of hacking I didn’t solve them all. Firstly, Bandcamp artist and album names are not normalized. Some artist names have spurious “The”, some album names have “(EP)” or “(single)” appended, so they don’t match your tags. These details are of interest only to librarians, but how can software tell the difference?

The simplest approach is use Musicbrainz, specifically cpe musicbrainz resolve-ids. By comparing ids where possible we get mostly good results. There are many albums not on Musicbrainz, though, which for now turn up as false positives. Resolving Musicbrainz IDs is a tricky process, too — how do we distinguish Multi-Love (album) from Multi-Love (single) if we only have an album name?

If you want to try it out, great! It’s still aimed at hackers — you’ll have to install from source with Meson and probably fix some bugs along the way. Please share the fixes!