iTunes 4.8 visualizer

May 21, 2005 10:40 AM

After spending a solid half hour staring at the new iTunes 4.8 visualizer and not seeing it loop around once, I started wondering how this was possible. Certain aspects repeat, but never in quite the same forms or colours. Is there a simple explanation?
posted by hopeless romantique to computers & internet (13 comments total)

If the iTunes visualizer is anything like Milkdrop or any of the Geiss visualizers for Winamp (which it seems to be trying to mimic), then it's a combination of a bunch of different wave styles, effect filters and color palettes. All of them play over one another randomly, in iTunes case. As you say, certain aspects repeat, but the number of different variables make for a few hundred (thousand?) combinations. If you want to see it in action, and you have a Windows machine handy, download Winamp and Milkdrop. It lets you change the different variables yourself and save them.
posted by eyeballkid at 11:08 AM on May 21, 2005

Actually, eyeballkid, I do believe you have your chronology reversed. Geiss didn't start working on visualizers at Nullsoft until 2001. iTunes, which was released the second week of 2001, has always had its visualizer, and there was a similar visualizer available as a plugin for iTunes' precursor, SoundJam, in 2000. So who's mimicing whom here?

If you want to know how iTunes' visualizer works, go to www.soundspectrum.com. It's pretty much what eyeballkid said, a bunch of different waveforms and delta-fields and color pallettes that get combined randomly. iTunes' visualizer is a lite version of G-Force, and there's full documentation available. I checked the 4.8 version to make sure it's the same...I'm not sure what you're seeing that's new, hopeless romantique. Then again, I usually use G-Force. Maybe they folded in some of the newer features Andy O'Meara's developed?
posted by jbrjake at 11:45 AM on May 21, 2005

to see what's going on in the itunes visualizer try playing around with the q/w, a/s and z/x keys. It will allow you to change the displacement map, wave style and colors. As was said the reason there don't seem to be repeats is because when on demo mode the three variables change at different rates. Apple apparently buys the GForce code off Andy every now and again to get new features. GForce allows you to make custom wave styles, maps and color palattes, but I find that the presets that ship with it are pretty nasty and need to be gone through. the Itunes viz is not really to my taste either. I still really like Andy's older visualizer -- Whitecap.
posted by n9 at 11:56 AM on May 21, 2005

There's no mimicry going on at all. Milkdrop and the iTunes visualizer aren't even comparable. Not even in the same league...or galaxy, for that matter. iTunes is pretty, but Milkdrop is just mindblowing.
posted by baphomet at 12:12 PM on May 21, 2005

question was about itunes.
posted by n9 at 12:23 PM on May 21, 2005

So who's mimicing whom here?

It's hardly an Apple or Nullsoft original.

These types of visualizers were available in the mid 90's as well. I had a DOS program that would generate all kinds of random patterns based on whatever CD was playing.

A lot of this goes back to the old PC demo scene.

They're essentially just fancy spectrum analyzers.


In short -- Unless you understand complex mathematical algorithms, there's no easy answer.
posted by o0o0o at 1:05 PM on May 21, 2005

The general answer is, combinatorial explosion. There are thousands of unique comments on metafilter, all formed of the same 26 (or 256) characters.

Assume that the visualizer has only eight independently varying -- that is, orthogonal -- variable, like colors, forms, sizes, etc. Assume each variable can take ten values, e.g., color might be one of ten colors, the current shape one of ten shapes, ten sizes.

We then have 10⁸ or one hundred million possible combinations of the eight variables. If the variables were changed to display a different combination every second, it would still take 1157 days, or over three years before all possible combinations were displayed.
posted by orthogonality at 1:38 PM on May 21, 2005

One easy way to learn about visualizers is to create some of your own.

Nullsoft's AVS (Advanced Visualization Studio) for Winamp lets you build up your own visualizations using simple elements, such as a waveform that changes with the music. You can then for example add a fadeout. There are a ton of effects you can use, and some are similiar to the effects in the iTunes visualizer. Some of the effects use a random number generator to drive them.

In the interest of full-disclosure, I used to do some development on Winamp plug-ins, so I'm a bit biased.

In short, the reason it doesn't repeat is because it fuses a combination of data from the song you're playing and random elements.

If you're interested in the technical details, many of the visualizers use something like a Fast Fourier Transform (Wikipedia, for beginners) to retrieve frequency information from the music.
posted by formless at 2:01 PM on May 21, 2005

Consider a very simple visualizer, in which up of one shape of one color starting at one screen position, "morphs" into another shape of another color at a second position. other than the shapes, the rest of the screen will be black; again, a bare-bones visualizer.

A modern computer display can shows colors that vary in 256 increments along three dimensions. Since this is more than most eyes can distinguish, and to purposely underestimate the variety of combinations, we'll use only 16 distinct values along each color "dimension". So we have a total of 16*16*16 = 16^3 = 4096 colors.

A modern computer display is at least 800 by 600 pixels. Again, since a human might not easily distinguish between two adjacent pixels, and to underestimate available combinations, we'll use only points that are exact multiples of 50 pixels. That gives us 800/50 = 16 positions along the width of the screen (the x axis) and 600/50 = 12 positions along the y axis, or 16*12 = 192 discrete starting or ending positions.

We'll start and end with one of five shapes: circle, triangle, square, pentagon, hexagon, and we'll let each shape take a radius or height of 5, 10, 15, or 20 pixels. This gives us 5 * 4 = 20 shape and size combinations.

20 shapes * 4096 colors * 192 starting points = 15,728,640 or over fifteen million starting graphics. Note that's because the starting graphic was made of 16*16*16 colors * 5 * 4 shapes * 16 * 12 positions, or seven independent variables, in case my ballpark of ten independent variables in my post above seemed too ambitious.

But remember we will morph to the ending graphic, adding another seven independent variables, giving us 15,728,640 - 1 possibilities (as it will be no fun if the graphic we morph to is the same as the one we start with). That gives us 15,728,640 * (15,728,640 - 1 ) = 247,390,100,520,960 or over 247 trillion combinations. And again, we were conservative by not using all the colors or positions or shapes or sizes at our disposal.

If we did one morph per second, it would take almost eight million years to see them all.
posted by orthogonality at 2:17 PM on May 21, 2005

Actually, eyeballkid, I do believe you have your chronology reversed. Geiss didn't start working on visualizers at Nullsoft until 2001.

" The latest version of Geiss is 4.24, released January 4, 2000."

Which, if my math is correct, is before 2001. I recall the Geiss visualizers being around a while before that, 1998 maybe? I don't know when he started working for Nullsoft. I didn't even know he worked for them, I always thought his plug-ins were third party things.

Regardless, my original answer is just a simpler explanation of ortho's more verbose reply above (even if my estimate of variations are way low ;).
posted by eyeballkid at 3:27 PM on May 21, 2005

something else you might want to consider is that unless the you're listening to the exact same music for four hours, even if the exact same settings DO repeat - you're going to be listening to different music and so it's going to look different.
posted by jaded at 3:59 PM on May 21, 2005

Skip all the math -- here is how it really works. The iTunes visualizer is (or at least was when Apple licensed it) Andy O'Meara's G-Force. As it turns out, O'Meara is an interesting guy: hardcore raver, devout Christian, and U.S. Navy officer.
posted by jjg at 4:20 PM on May 21, 2005

Don't forget one of the oldest, Cthugha, dated back 'to 94 or so.
posted by tomble at 2:11 AM on May 22, 2005