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More iTunes Math
Posted by
Zonk
on Sat Feb 11, 2006 06:21 PM
from the fun-and-learning-like-pb-and-j dept.
from the fun-and-learning-like-pb-and-j dept.
markmcb writes "OmniNerd once again digs into the math behind iTunes. The 5-star ratings in iTunes are actually stored in a variable allowing values from 0 to 100, with 20 = 1-star, 40 = 2-star, etc. Known to few, if you set a rating to 30 (manually), it will show up as 1 1/2 stars in the program's GUI. Matt Schinckel provides interesting statistical evidence showing that not only do non-whole, non-half values (e.g., 47) not increase the amount a song will play, but neither do the half-star ratings (with the exception of .5 star)."
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Apple: Crunching the Math On iTunes 276 comments
markmcb writes "OmniNerd has posted an interesting article about the statistical math behind iTunes. The author makes some interesting observations concerning the same song playing twice in a row during party shuffle play, the impact that star ratings have on playback, and comparisons with plain old random play (star ratings not considered)." From the article: "To test the option's preference for 5-stars, I created a short playlist of six songs: one from each different star rating and a song left un-rated. The songs were from the same genre and artist and were changed to be only one second in duration. After resetting the play count to zero, I hit play and left my desk for the weekend. To satisfy a little more curiosity, I ran the same songs once more on a different weekend without selecting the option to play higher rated songs more often. Monday morning the play counts were as shown in Table 1."
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How does it handle values outside the range? (Score:2)
Re:How does it handle values outside the range? (Score:5, Interesting)
Parent
Re:How does it handle values outside the range? (Score:4, Informative)
No they aren't. I'm a professional programmer for a Mac (and PC) program using the Carbon interface for Macs. As Wikipedia says, "Carbon is more versatile in that it may be accessed using C, C++, Pascal, Ada, or any other language with suitable interface headers, whereas Cocoa exclusively uses Objective C and Java." Most cross-platform apps use Carbon because Objective-C isn't widely used on PCs.
Parent
Re:So it's basically fixed point math. (Score:5, Funny)
Whatever it is the editors were smoking.
Parent
Re:So it's basically fixed point math. (Score:5, Funny)
This story has everything to do with what this site stands for. It directly involves Apple, mathematics, software design, software analysis, software realiability, and so forth.
Remember, one of the traits of the true, traditional hacker was to experiment with systems in order to better understand them. That holds especially true of proprietary software systems, where the source code cannot be easily or readily viewed.
Indeed, this is a very interesting story that should appeal perfectly to the general Slashdot audience.
Parent
Re:So it's basically fixed point math. (Score:5, Insightful)
The hacker audience who is interested in such things has been dwindling both in numbers and as a percentage. Now the "general Slashdot audience" prefers to fawn over the latest consumer product from Apple, to complain about Microsoft, or to inexpertly argue their "Rights Online".
Articles about technology, impressive hacks, homebrew projects, science and mathematics would be extremely welcome. Unfortunately the editors are infatuated with content-free articles that are little more than advertisements for products like the PS3 and Xbox and iPod.
Parent
How does the Windows version work? (Score:3, Interesting)
Basically the same... (Score:3, Informative)
Scripts to do it can be found here: http://ottodestruct.com/blog/category/geekery/pro
closed source.. (Score:3, Interesting)
Obligatory (Score:5, Funny)
Tsk, and I thought this was Slashdot... bleeding edge, people!
Re:Obligatory (Score:5, Funny)
I tried to install Songbird, but it just installed a buggy, broken and cluttered version of iTunes that didn't work with my iPod and had a farting bird for an icon. Does anyone know where the real installer is?
Parent
Re:Obligatory (Score:3, Funny)
why linear? (Score:5, Interesting)
Re:why linear? (Score:3, Insightful)
Man, do you really want your favorite song to play 32 times for every 0-star rated song you have on your iPod? I don't care how much you love a song, after listening to it that often, you're bound to want to stab your iPod in the face. Or the closest fan of The Cure. Come to think of it, that'd be a win-win situation.
Re:why linear? (Score:3, Interesting)
Instead I rate my tracks like I would a movie.
1-star is probably going to get deleted eventually.
2-stars play half as much as No-stars.
No-stars play twice as much as 2-stars.
3-stars play 3 times as much as 2-stars.
4-stars play 4 times as much as 2-stars.
5-stars pla
Smart Shuffle might have something to do with it (Score:3, Insightful)
The first control is a 3-setting slider for "more likely, random, less likely". The description below says "Smart shuffle allows you to control how likely you are to hear multiple songs in a row by the same artist or from the same album."
Below that are three radio boxes, labled Shuffle: ( ) Songs ( ) Albums ( ) Groupings.
Is it possible that this 100 scale rating system might be more fine grained to take these Smart Shuffle user settings into account? Perhaps that might be why it isn't simply the integers 0-5.
5 Stars Rating Systems are Poor Design (Score:3, Interesting)
Re:5 Stars Rating Systems are Poor Design (Score:3, Interesting)
Re:The beauty of AppleScript. (Score:5, Funny)
This shows the level of brainwashing only possibly seen in apple zealots.
Parent
Re:The beauty of AppleScript. (Score:5, Funny)
Parent
Re:The beauty of AppleScript. (Score:4, Funny)
Parent
Re:The beauty of AppleScript. (Score:3, Funny)
Future considerations, perhaps? (Score:4, Insightful)
Suppose in the future they added support for giving a song a percentage ranking. It's quite easy to do with the system they're using now. Data from the new software could be used with the old, as the old software is already expecting and can cope with a value in the 0 to 100 range, even if it does so slightly differently than the future versions.
Parent
Re:Is it really surprising? (Score:5, Informative)
Many people who read this site care about issues like this. We find it interesting to experiment with software systems, especially those which we do not have direct access to the source code of. It's fun to see how a consumer-grade application reacts to unexpected data, for instance.
He could have decompiled the application. But doing so would likely have been in violation of the licensing agreement he agreed to before using said software. You may question the legality of such agreements, but he may not have wanted to take the risk of publishing his findings. Litigation is expensive, after all.
Not only that, but it's quite difficult to decompile a program written in C, C++ or Objective-C. That's especially true when you're dealing with an optimized program. It often isn't obvious what a particular chunk of assembly code is doing, and thus is basically useless for such analysis.
Parent
Re:I'm just saying this... (Score:3, Insightful)