Shuffling tracks, by custom criteria (ex, album)

[Jud Craft]

A thought experiment to demonstrate the problem.

Imagine you have the following library:

A 300+ song collection of instrumental music (one of those giant
Norton Musical Anthologies of Western Civilization or whatever) and
roughly 300-400 songs of scattered artists and albums.  So, nearly
half your library is from the same album/album artist.

Your 300-400 songs of Everything Else may have a lot of great variety,
but when you do a shuffle, what's going to happen?  Nearly half the
time, you're going to get instrumental music.  This is because of
per-track shuffle, I guess:  every track is equally worthy of being
played as any other track.

Now, I would love it if I could tell Amarok to shuffle by album
artist, or by album.  (Note that this is _not_ the same as Shuffling
Albums, which I think is what Amarok 1.4x did when Shuffle by Album
was chosen:  that is, randomly picking one album, then playing the
whole album, then picking another album and repeat.  What I would like
is still Shuffling Tracks, but by an alternate criteria, such as
genre, album artist, or album).

For example, I could then click "Shuffle Tracks" - "by Album Artist",
and on every new track, Amarok would randomly choose between the list
of Album Artists (or the Artist for songs missing the A.Artist. tag),
and from there it would randomly choose a song.

So, all of my Norton music stops receiving a 50% probability, and
instead, it takes up 1 of possibly 150 artists/album artists.  Giving
me a shuffle that gives much more variety in my music.

Note:  I don't think this falls under the Bias functionality:  I don't
want to dynamically assemble a playlist that only has 1% instrumental:
 I still want to play through my entire collection, I just want Amarok
to shuffle by a criteria that allows me a more dynamic shuffle
(dynamic in terms of music content), rather than the randomness of
pure chance alone, which gives more variety with a less heterogenous
collection.

(This would mean that yes, on average, your Everything Else songs
would get played much more often than any song belonging to a criteria
(album, genre) with a TON of songs.  That's what I'd like -- a
compensation for the homogenousness of my collection).