https://bugs.kde.org/show_bug.cgi?id=240301

           Summary: Automatic play list is not very random or mixed
           Product: amarok
           Version: 2.3.1
          Platform: Fedora RPMs
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: NOR
         Component: Playlists/Automated Playlist Generator
        AssignedTo: amarok-bugs-dist@kde.org
        ReportedBy: bk+bugzilla@mksoft.nu
                CC: stharward@gmail.com


Created an attachment (id=47540)
 --> (http://bugs.kde.org/attachment.cgi?id=47540)
Preset

Version:           2.3.1 (using KDE 4.4.3) 
OS:                Linux

I've created an automatic playlist preset as per the included screenshot,
basically asking for a playlist of around 1 hour (but don't seem to matter if I
increase this), no duplicates, at least 3 star from two artists, X and Y.

On generating playlists, the resulting playlists tend to have at most one or
two tracks by artist Y, and all the rest by artist X.

Now, granted, that _technically_ meets the _constraints_ specified (as there is
no way to specify what fraction of the total each artist should represent). It
does, however, not meet _expectations_.

Now, in my database I have about a 3:1 ratio of artist X to Y, but the ratios
in the generated playlists are fairly consistently worse than that, and
besides, if I list two artists in the preset, I would _expect_ that they would
be represented in the generated list in (roughly) equal proportions.

This said, my preferred solution would be if I were either permitted to specify
a fraction, or if the playlist length could be specified per subgroup, i.e.:

"Match all" group
  playlist length: 2:00:00
  "Match all" group
    local playlist length: 0:45:00
    tag artist: "X"
  "Match all" group
    local playlist length: 0:30:00
    tag artist: "Y"
  tag rating: >2.5

and get a 2 hour playlist of 3-star or better tracks consisting of 45 minutes
of artist X, 30 minutes of artist Y, and the remaining 45 minutes mixed music
by artist other than X or Y

Of course, I would rather have it be something like:

"Match all"
  playlist length: 2:00:00
  40% tag artist: "X"
  30% tag artist: "Y"
  tag rating: >2.5

...but having the fraction generated by "tag artist" be a function of either
its position in the preset, or the number of matching fields in the database is
rather counterintuitive.

Reproducible: Always

Steps to Reproduce:
Well, not _quite_ every time, but damn near.

1. Create preset.
2. Generate playlists.
3. Boggle over the result.

Actual Results:  
Playlist looks like:
X
X
X
X
X
Y
X
X
X
X


Expected Results:  
Ought to look like:
X
X
Y
X
Y
Y
X
Y


Tried swapping order of "tag artist" entries, same result, so does not seem to
be due to order in the preset. Also tried changing artist X for artist Z, where
the ratio of Y to Z was 3:1, and then Y was wildly overrepresented in the
generated lists. It appears that the generation somehow magnifies the ratio in
the database.

I.e., a ratio of 3:1 in the database often generates a playlist where the ratio
is 6:1 - 9:1.

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