I can offer some empirical evidence of this... I just had three out of a group of four songs come from the same playlist in a full shuffle of the entire empeg and I have over 160 playlists containing a total of 1449 tracks.

While it's certainly the case that there are deficiencies in the shuffle algorithm, I have to point out that your example isn't really empirical evidence of anything. :) I mean, I have over 3000 tracks, and occasionally I have 2 tracks in a row (or 3 out of 4) come from the same playlist - but you'd expect this to happen sometimes in a random shuffle; it's no more or less likely than any other set of 3 or 4 songs coming up in sequence.

Now, if the shuffle were a two-tiered algorithm, where it shuffled "playlists" to get a sequence of playlists to pick tracks from, and then picked the actual tracks from those playlists in another random draw, it'd become less likely to have multiple songs from the same playlist close together; but still possible, of course, unless the algorithm actually took steps to guarantee that that didn't happen. But then you're imposing structure on the random ordering ("the same playlist can't be chosen twice without at least N playlists being chosen in between"), which in and of itself will make it less random/more predictable. Something like this, as I understand it, is being done on a per-track basis for 1.1 (tracks which have been played less often have a better chance of popping up earlier in a shuffle - correct?), but that still doesn't do anything about your example.

You can't really win; except by getting a good source of randomness in the first place and sticking to it. Easier said than done, of course. :)

-Dan

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Daniel M. Zimmerman
Mk.2 #060000058, 36GB, Red
Mk.1 #00101, 10GB, Blue