Audio React
This control section lets you set audio tracks that will affect the particle grid in a variety of ways. Form can extract loudness data from audio files and create keyframes automatically to drive other controls in the plug-in. The five "Reactors" offer controls that let you specify frequency ranges (such as bass, midtones, or trebles) that then drive a specific parameter based on the loudness of the frequency over time.

Reading the Reactor
Before we get into the controls, it is helpful to look at some Audio Reactor controls in a real example. In the screen shot above, you see that we have an audio layer chosen, AquoVisit.wav from Adobe's Production Studio CS3 demo media. This is the source file that we will use to drive the animation.

Reactor 1 is open and the Time Offset is 0.00--this means that the current time of the playhead is used to grab the audio sample. Next, the Frequency and Width are set to choose a band of sound centered at 800 Hz with a width of 75 Hz. This means that we're instructing Form to only listen to a selected range of sound in the midtones, centered around 800 Hz. Here is a sample of the band of sound that Form is extracting: 800 Hz sample. Within that specified band of sound, Form will evaluate the loudness and assign a number to drive the Particle Size as designated in the Map To pop-up. The Particle size is currently set to 2. Form then computes the loudness, multiplies it by the strength factor, and then multiplies by the particle size and then draws each particle at that size.

If Delay Max is set to zero, Form will simply change the particle size at that instant in time across the entire grid. But what if we want a ripple effect, or a movement that seems to travel across the grid in time with the music? That's where Delay Direction and Delay Max come into play.

To create a an effect over time, the plug-in must specify where and when the reactor will apply the Particle size. The Delay Direction is set to move inward (from the outer edges of the form shape in 3D space) over a period of .2 seconds (the Delay Max value), which creates a rippling change in the Particle size. Whew! It sounds crazy, but it lets you generate dynamic visuals in just a few seconds.
Audio Layer
Select the audio layer to use. Note: When working on Windows, we recommend using 44Khz, 16-bit .wav files. These seem to process much faster than other audio formats, and .mp3 format seems to be particularly slow. You can use QuickTime Player Pro or another audio processing tool to convert other formats to .wav files.
Reactor 1-5
All five reactors offer exactly the the same set of controls. Multiple controls are useful for driving different control values with the Map To command.

Each Reactor has the following options:
Time Offset
Adjusts the timing. It basically slides the time sampling forward or backward from the current time indicator.
Frequency
Defines the active frequency for the Reactor. For example, roughly 50-500 Hz is the bass, 500-5000 Hz is the midtones and above 5000 Hz is the highs/trebles.
Width
Defines how wide the frequency response is that Form will use to sample the loudness from the audio. 100 means it is wide and 1 is a very narrow (specific) frequency response. So, to select only the sound from a bass drum, you'd want to select a low Frequency and a relatively narrow width.

Threshold
This value is basically subtracted from the output so that a minimum level is required for any visible effect. This is useful when there is a lot of background noise in a recording, or wide-frequency sounds that interfere with the desired sounds.
Strength
Defines how strong the effect is on the parameter and is used as a multiplier to the Map To value. Large Strength values can cause huge changes in the image, so use this carefully. Also, since this value is a multiplier, you will need to set some value in the control that the Reactor is affecting. For example, if the Map To is set to the Disperse value, then you need to set a Disperse value that is greater than 0.
Map To
The audio reactor can drive other controls in the plug-in. For example, choosing Particle Size from the Map To menu will alter the current Particle Size setting in the Particle section of the plug-in. To define which controls will be affected, choose one of the following from the pop-up menu: Particle Size, Particle Opacity, Fractal, Disperse, Displace X, Displace Y, Displace Z, Sphere 1 Size, Sphere 1 Strength, Sphere 2 Size, Sphere 2 Strength, TW Scale (Transform Scale), TW Offset X (Transform Offset), TW Offset Y (Transform Offset), and TW Offset Z (Transform Offset).
Delay Direction
Allows you to select the direction in which the audio reactor delay travels or ripples through the form. Direction options include: X Left to Right, X Right to Left, X Outwards, Y Top to Bottom, Y Bottom To Top, Y Outwards, Z Back to Front, Z Front to Back, Z Outwards, Outwards (from the center), and Inwards (towards the center). This is used in concert with the Delay Max control to allow the system to generate a traveling animation that is offset in the chosen direction over the period set by Delay Max. The following screen shots show a X Left to Right Reactor used to drive Disperse, with a Delay Max of .25 seconds.

The first frame - no dispersion | Dispersion starts on the left
Dispersion moves across midpoint | Dispersion completes one traversal in .25 seconds

Delay Max
Defines the length of the delay buffer, which is the maximum time a sound stays "visible" as ripples in the Delay Direction option chosen above.
X Mid, Y Mid, Z Mid
Only used for the Delay Direction -- Outwards and Inwards. Defines the position in 3D space inside the particle grid where the sound is first/last seen - the point where sounds ripple from or towards.