The Perception of 'Random' on the iPod 292
Robaato writes "Stephen Levy writes in the Guardian about the perception of randomness, or the lack thereof, on an iPod set to shuffle." From the article: "My first iPod loved Steely Dan. So do I. But not as much as my iPod did.... I didn't keep track of every song that played every time I shuffled my tunes, but after a while I would keep a sharp ear out for what I came to call the LTBSD (Length of Time Before Steely Dan) Factor. The LTBSD Factor was always perplexingly short." My first iPod shuffle refused to let me delete (sigh) Weird Al's Polkamon off of the flash memory.
Bias (Score:5, Informative)
Re:And Zonk dupes himself... again... (Score:5, Informative)
That article is btw referenced in this one.
Old News. (Score:5, Informative)
I personally have had it happen where my iPod is in shuffle mode and I've heard not just two songs in a row by the same artist, but a song plays and then the next song from that album follows it. And that's with a library of over 5,000 songs. Naturally it's more likely to happen on a much smaller Shuffle with a fraction of the songs.
Re:OCD (Score:5, Informative)
It's because of the birthday paradox (Score:4, Informative)
The basic gist is that their are far more possible pairs than we'd intuitively imagine. For example, with 20 albums of 20 songs each, the chance of two songs in a row being from the same album is actually:
400/400 * 20/400 = 1/20
Which makes a lot of sense once you sit down and think about it, but is a lot higher than an uneducated guess.
This is the same reason that collision/timing attacks are feasible.
RTFA (Score:5, Informative)
FTFA: Or
Check the play count (Score:3, Informative)
(I looked at mine; it was closer to uniform than I'd perceived. There's also a "Skip Count", but it's blank for all my songs.)
Re:And Zonk dupes himself... again... (Score:3, Informative)
Similar to radio stations (Score:5, Informative)
There's a simple parameter that's set to control, to within one minute, the amount of temporal separation there must be between playing two songs from the same artist, or the same song twice. The radio algorithm is a little more complicated, since songs aren't in just one big batch like the iTunes library, but in different categories, based generally on the perceived desire of target listeners to hear a given new song, or like and identify with a given older song.
The system is built off the (once literal, now metaphorical) use of index cards: The format clocks say, e.g., at the top of the hour, play a P category song, followed by a B category song, then a G, then an A, etc. You'd have a set of rules, like "don't play the same artist within 45 minutes" or "don't play the same current song within 3 hours", and you'd take the first card in the category that fit all the rules, play it, and move the card to the back of the stack.
Basically, what Apple is doing with that slider is enabling artist separation control, which is completely one of the illusions radio stations (used to) use to convince you they had every song under the sun available to them.
Re:Bias (Score:2, Informative)
Re:Bias (Score:5, Informative)
Some years ago, I worked on an mp3 playing device (no, not Apple). Our users were quite often complaining that our random was not truly random, and seems to be clustering, favoring, disliking some thing or another. Some would swear that there was some intelligence to it, picking particular songs. I've seen the shuffle code, it's a simple array swap. I ran a numerical simulation on the output and found that the distribution of the array elements from their original position equal throughout. Further, there seemed to be no specific clustering, as the probability that any item would end up next to any of its peers was again equally distributed throughout. We had some of the customers submit their own ideas and tried them out in code. In general, we found that we never outperformed the simple array swap in terms of randomness, though most results were about the same.
The conclusion that we reached: If you have a lot of Jimmy Buffet, you're going to hear a lot of Jimmy Buffet. And on that one occassion that two Buffet songs play back to back, you're going to think to yourself "this random sucks". But it is, in fact, all in your head.
*I'm sure someone will want to bring up the seed issue. Let's just say that we had it covered.
Re:Bias (Score:2, Informative)
Re:Bias (Score:1, Informative)
They have a hard disk and a memory cache. Each time they have to spin the disk to read songs not in the cache, lots of power is consumed. To increase the battery time, the iPod will always prefer to play whatever's already in the cache.
I'm sure they meant well when they did this, but the result is truly devastating for many use cases, because it will cause the iPod to always prefer what you have heard recently over anything else when you switch back and forth between different random selections. It is especially bad that this optimization is also in play when the iPod is running on net power. There should at least be an option to switch to true (pseudo)randomness, right now the only workaround I know is to blow the cache by letting it play random songs from the entire library over a very long period.
To verify that this is true, try the following experiment: Play one song from an album you haven't listened to for a while, then choose to play all the songs from that album in random order. Guess which one comes first.
Re:Bias (Score:3, Informative)
iTunes 7 does.
Mind, it doesn't do anything particularly useful with it, but you have Last Skipped and Skip Count available for Smart Playlists, so you could probably get some way towards what you want...