Description

Fixes issue in which thumbnails were rescaled locally instead of downloading pre-sized ones from CAA.

From the docs:

The CAA provides pre-sized thumbnails of width 250, 500, and 1200 pixels. If you set the maxwidth option to one of these values, the corresponding image will be downloaded, saving beets the need to scale down the image. It can also speed up the downloading process, as some cover arts can sometimes be very large.

I noticed that the fetchart plugin didn't download the pre-sized thumbnails from CAA for some of my releases because the API didn't provide them under the keys "500" and "250" but instead "large" and "small". These are legacy keys but for some releases they're the only ones available so I wrote this fix to use them as a fallback.

Example

curl -sL "https://coverartarchive.org/release/d51434bc-fcb6-4fc0-864f-e1ab13a51de2" | jq

{
  "images": [
    {
      "types": [
        "Front"
      ],
      "front": true,
      "back": false,
      "edit": 30140717,
      "image": "http://coverartarchive.org/release/d51434bc-fcb6-4fc0-864f-e1ab13a51de2/8891190287.png",
      "comment": "",
      "approved": true,
      "id": "8891190287",
      "thumbnails": {
        "large": "http://coverartarchive.org/release/d51434bc-fcb6-4fc0-864f-e1ab13a51de2/8891190287-500.jpg",
        "small": "http://coverartarchive.org/release/d51434bc-fcb6-4fc0-864f-e1ab13a51de2/8891190287-250.jpg"
      }
    }
  ],
  "release": "http://musicbrainz.org/release/d51434bc-fcb6-4fc0-864f-e1ab13a51de2"
}