A Guess of How iTunes' "Smart Shuffle" Might Be Designed to Work

iTunes 5.0 has a feature which enables users to "control how likely you are to hear multiple songs in a row by the same artist or from the same album". This is an easy guess on how it works:

When you drag the slider right in the middle, it is set to true "random", absolutely a random calculation by the CPU and thereafter the corresponding choice, every item gets the same possibility of being chosen as the next one to be played, no matter how you may feel it is not. When you drag it to the right, depending on the distance percentage of how much you move to the right end, the algorithm deducts a same percentage number of songs with the same artist or same album name (including the song right in playback) from the library, and then makes a true-random calculation in the remaining library. When you drag the slider to the end of the right, the percentage reaches 100% thus all the songs from a same album or artist are all put away from the choosing pool, so you won't hear any of these songs immediately following the current song, unless in your library you just don't have any two songs that have different artist name and album name. The same method applies when you drag the slider to the left, what is different is the objects of deduction – they are the songs with a different artist name and (not or) different album name from the song currently being played.

Just a random guess. It is very likely that they have used a much simpler/more complicated means. But even after I have adjusted the slider exactly to the right end, I still hear two songs from Andy Lau in a Row, freak! This is not right…