SuperCollider CLASSES

IFFT

Inverse Fast Fourier Transform

Description

The inverse fast fourier transform converts from frequency content to a signal.

The fast fourier transform analyzes the frequency content of a signal. The IFFT UGen converts this frequency-domain information back into time-domain audio data. Most often this is used as the end of a process which begins with FFT, followed by frequency-domain processing using PV (phase-vocoder) UGens, followed by IFFT.

Class Methods

*new (buffer, wintype: 0, winsize: 0)

*ar (buffer, wintype: 0, winsize: 0)

*kr (buffer, wintype: 0, winsize: 0)

returns a time domain signal from converting the FFT frequency domain signal chain. The *new method is equivalent to the *ar message returns an audio rate signal.

Arguments:

buffer

The FFT "chain" signal coming originally from an FFT UGen, perhaps via other PV UGens.

wintype

Defines how the data is windowed:
-1rectangular windowing, simple but typically not recommended;
0(the default) Sine windowing, typically recommended for phase-vocoder work;
1Hann windowing, typically recommended for analysis work.

winsize

Can be used to account for zero-padding, in the same way as the FFT UGen.

Returns:

The time-domain audio signal.

Discussion:

The IFFT UGen converts the FFT data in-place (in the original FFT buffer) and overlap-adds the result to produce a continuous signal at its output.

Inherited class methods

Instance Methods

Inherited instance methods

Examples

// without any modification, convert FFT chain (frequency domain signal) back to audio (time domain signal)
(
{   var in, chain;
    in = WhiteNoise.ar;
    chain = FFT(LocalBuf(2048), in);
    IFFT.ar(chain) * -20.dbamp // inverse FFT
}.play;
)