fft~
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fft~

Fast Fourier transform

Description

fft~ performs a Fast Fourier transform on any incoming signal and outputs the real and imaginary parts of that transform as well as a synchronization signal.

Examples

Fast Fourier transform of an audio signal

Arguments

number-of-FFT-samples [int]

Optional

The first argument specifies the number of points (samples) in the FFT. It must be a power of two. The default number of points is 512.

spectral-frame-size [int]

Optional

The second argument specifies the number of samples between successive FFTs. This must be at least the number of points, and must also be a power of two. The default interval is 512.

phase [int]

Optional

The third argument specifies the offset into the interval where the FFT will start. This must either be 0 or a multiple of the signal vector size. fft~ will correct bad arguments, but if you change the signal vector size after creating an fft~ and the offset is no longer a multiple of the vector size, the fft~ will not operate when signal processing is turned on.

Attributes

Common Box Attributes

annotation [symbol]

Sets the text that will be displayed in the Clue window when the user moves the mouse over the object.

background [int] (default: 0)

Adds or removes the object from the patcher's background layer. background 1 adds the object to the background layer, background 0 removes it. Objects in the background layer are shown behind all objects in the default foreground layer.

color [4 floats]

Sets the color for the object box outline.

fontface [int]

Sets the type style used by the object. The options are:

plain
bold
italic
bold italic

Possible values:

0 = 'regular'
1 = 'bold'
2 = 'italic'
3 = 'bold italic'

fontname [symbol]

Sets the object's font.

fontsize [float]

Sets the object's font size (in points).

Possible values:

'8'
'9'
'10'
'11'
'12'
'13'
'14'
'16'
'18'
'20'
'24'
'30'
'36'
'48'
'64'
'72'

hidden [int] (default: 0)

Toggles whether an object is hidden when the patcher is locked.

hint [symbol]

Sets the text that will be displayed in as a pop-up hint when the user moves the mouse over the object in a locked patcher.

ignoreclick [int] (default: 0)

Toggles whether an object ignores mouse clicks in a locked patcher.

patching_rect [4 floats] (default: 0. 0. 100. 0.)

Sets the position and size of the object in the patcher window.

position [2 floats]

g/s(set)

Sets the object's x and y position in both patching and presentation modes (if the object belongs to its patcher's presentation), leaving its size unchanged.

presentation [int] (default: 0)

Sets whether an object belongs to the patcher's presentation.

presentation_rect [4 floats] (default: 0. 0. 0. 0.)

Sets the x and y position and width and height of the object in the patcher's presentation, leaving its patching position unchanged.

rect [4 floats]

g/s(set)

Sets the x and y position and width and height of the object in both patching and presentation modes (if the object belongs to its patcher's presentation).

size [2 floats]

g/s(set)

Sets the object's width and height in both patching and presentation modes (if the object belongs to its patcher's presentation), leaving its position unchanged.

textcolor [float]

Sets the color for the object's text in RGBA format.

textjustification [int]

Text Justification

Possible values:

0 = 'left'
1 = 'center'
2 = 'right'

varname [symbol]

Sets the patcher's scripting name, which can be used to address the object by name in pattr, scripting messages to thispatcher, and the js object.

Messages

phase

Arguments

offset [int]
Offset from the beginning of a period when the FFT is performed.

signal

In left inlet: The real part of a complex signal that will be transformed.

In right inlet: The imaginary part of a complex signal that will be transformed.

If signals are connected only to the left inlet and left outlet, a real FFT (fast Fourier transform) will be performed. Otherwise, a complex FFT will be performed.

Output

signal

Out left outlet: The real part of the Fourier transform of the input. The output begins after all the points of the input have been received.

Out middle outlet: The imaginary part of the Fourier transform of the input. The output begins after all the points of the input have been received.

Out right outlet: A sync signal that ramps from 0 to the number of points minus 1 over the period in which the FFT output occurs. You can use this signal as an input to the index~ object to perform calculations in the frequency domain. When the FFT is not being sent out (in the case where the interval is larger than the number of points), the sync signal is 0.

See Also

Name Description
cartopol Convert cartesian to polar coordinates
cartopol~ Signal Cartesian to Polar coordinate conversion
fftin~ Input for a patcher loaded by pfft~
fftinfo~ Report information about a patcher loaded by pfft~
fftout~ Output for a patcher loaded by pfft~
frameaccum~ Compute "running phase" of successive phase deviation frames
framedelta~ Compute phase deviation between successive FFT frames
ifft~ Inverse fast Fourier transform
index~ Read from a buffer~ with no interpolation
pfft~ Spectral processing manager for patchers
poltocar Convert polar to cartesian coordinates
poltocar~ Signal Polar to Cartesian coordinate conversion
vectral~ Vector-based envelope follower
MSP Analysis Tutorial 3: Using the FFT MSP Analysis Tutorial 3: Using the FFT