FFT is short for Fast Fourier Transform, Full Fat Twinkies and Freakishly Funky Telegrams. But mostly the first one.
FFT is used in Arena and Avenue to get the amplitude(loudness) of a set frequency band or range. When a big fat kick is coming, the 10 to 200 hertz frequency bands are likely to spike.
You might know FFT already from Resolume Arena and Avenue. It is the setting that makes your visuals respond to incoming audio. It is possible to transmit this data to Wire and make it do all sorts of amazing things. This article is here to teach you all about that.
Let's start with the why question, why would you want FFT data in your Wire patch? The answer is simple: more control. Wire will receive the FFT data as an array of 1024 float values which each correspond to a frequency band. We will later explain how this exactly works as it is a rather advanced topic.
With this data you could make something rotate on a kick, shake on a snare and change color based on the overall amplitude of the sound.
To get the data into Wire simply create a Spectrum In node. This node will give you 1024 float values to work with. The lower the index, the lower the frequency.
The maximum frequency is dependent on your sample rate, this can be set in the preferences of Arena or Avenue.
The width of each band can be calculated by first dividing the sample rate by two. Take that value and divide it by 1024.
With a sample rate of 48000 you will end up with frequency bands of approximately 23 hz per band. So index 0 will cover the 0 to 23 hz bands, index 9 will cover 230hz to 253hz and so on.
It is important to remember that the hearing limit of most adults is between 15khz and 17khz.
This means that when we use a sample rate of 4800, index 675(15.525hz) and up might be out of range and therefore less useful.
A patch that contains the Spectrum In node will create a spectrum in tab in the effect, source or mixer you have made. This is a simple drop down menu where you can choose between local, composition or external.
If you choose local, the audio playing on the clip will be used.
If you choose composition, all the audio playing in the composition will be used.
If you choose external, the external FFT source set in the preferences will be used.
The chosen source will be used for the patch.