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Sound draws a spiral. If you start from C, and go up the stairway of notes to D, E, F, and so on, you’ll get to another C, which is not the same place you previously were but one floor up from where you started. Since the ratio of frequencies of two notes an octave apart is 2:1, going up one floor means doubling the frequency.
So what if this relationship were literally visualized in 3D animation? The result did not turn out very simple and clear since even a single note of an instrument contains multiple frequencies as its component. But at least it’s somewhat fun to watch, isn’t it?
Clicking on the demo below starts/stops the sound. Watch out for the volume on your PC.

Sound.comuteSpectrum() method, which is used to analyze the sound, seems to have several problems. One of them that is critical is that the method doesn’t work properly when more than two movies play sound simultaneously in FireFox. If you don’t see the demo, try closing other browser windows.

Another demo that works without music is also posted to wonderfl.

An experiment on turning a video image into some kind of environmental music, noise, or whatever.
The idea itself is not at all new, but what I found interesting is that flash player(or AIR application) keeps interacting with the movement in the camera even while it is in the background. This means that it is possible to make an application that stays in background but is controllable through gestures.

Since the wavelength is inversely proportional to frequency, the pitch of sound can be modulated by shortening the sample data discarding some portion of it.
Based on the example on the on-line reference that make the sound octave high, I made a sample that shifts the pitch by half tones.

In equal temperament, the ratio of the wavelength of a note to the next is two to the one twelfth power, and this ratio is used to determine the amount of sample data to be skipped.
Actually, this sample is more like playing a tape at a fast-speed. I was thinking how real pitch-shift that doesn’t change the duration can be realized but couldn’t come up with the answer. Any idea?