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fftin~ Reference

Input for a patcher loaded by pfft~

fftin~

Description

The fftin~ object provides an signal input to a patcher loaded by a pfft~ object.

Examples

fftin~ outputs a frequency/domain signal pair and a sync signal that indicates the bin number

Discussion

Where the pfft~ object manages the windowing and overlap of the incoming signal, fftin~ applies the windowing function (the envelope) and performs the Fast Fourier Transform.

Arguments

inlet-assignment [int]

Determines the inlet number of the pfft~ which will be routed into the fftin~ object. Inlet assignment starts at one, for the leftmost inlet in the pfft~. Multiple fftin~ objects will typically have different inlet numbers.

window-envelope-function [symbol]

Optional

Specifies the window envelope function the fftin~ object will apply to overlapping FFTs on the input signal. The options are square (i.e. no window envelope), hanning (the default), triangle, hamming and blackman (Note: The Blackman window should be used with an overlap of 4 or more). If the symbol nofft is used, then the fftin~ object will not use a windowing envelope and will not perform a Fast Fourier Transform -- it will echo the first half of its input sample window to its real output and the second half of its input sample window to its imaginary output. This can allow you to input raw control signals from outside the parent patcher through inlets in the pfft~ object, provided its overlap is set to 2. Other overlap values may not yield useful results.

Attributes

Common Box Attributes

Messages

signal

Dummy inlet. The signal input for an fftin~ object is an inlet in the pfft~ subpatcher which contains the object.

Output

signal

Out left outlet: This output contains the real-values resulting from the Fast Fourier transform performed on the corresponding inlet of the pfft~. This output frame is only half the size of the parent pfft~ object's FFT size because the spectrum of a real input signal is symmetrical and therefore half of it is redundant. The real and imaginary pairs for one spectrum are called a spectral frame.

Out middle outlet: This output contains the imaginary-values resulting from the Fast Fourier transform performed on the corresponding inlet of the pfft~. This output frame is only half the size of the parent pfft~ object's FFT size because the spectrum of a real input signal is symmetrical and therefore half of it is redundant. The real and imaginary pairs for one spectrum are called a spectral frame.

Out right outlet: A stream of samples corresponding to the index of the current bin whose data is being sent out the first two outlets. This is a number from 0 - (frame size - 1). The spectral frame size inside a pfft~ object's subpatch is equal to half the FFT window size.

See Also

Name Description
Spectral Processing Spectral Processing
Sound Processing Techniques Sound Processing Techniques
cartopol
cartopol~
fft~
fftinfo~
fftout~
frameaccum~
framedelta~
ifft~
in
out
pfft~
poltocar
poltocar~
vectral~
MSP Analysis Tutorial 4: Signal Processing with pfft~ MSP Analysis Tutorial 4: Signal Processing with pfft~