fftin~

Input for a patcher loaded by pfft~

Description

The fftin~ object provides an signal input to a patcher loaded by a pfft~ object; it won't do anything if you try to use it anywhere other than inside a patcher loaded by the pfft~ object. 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

Name Type Opt Description
inlet-assignment int Obligatory. 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 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.

Messages

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

Information for box attributes common to all objects

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.

Examples

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

See Also

Name Description
cartopol Cartesian to Polar coordinate conversion
cartopol~ Signal Cartesian to Polar coordinate conversion
fft~ Fast Fourier transform
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
in Message input for a patcher loaded by poly~ or pfft~
out Message output for a patcher loaded by poly~ or pfft~
pfft~ Spectral processing manager for patchers
poltocar Polar to Cartesian coordinate conversion
poltocar~ Signal Polar to Cartesian coordinate conversion
vectral~ Vector-based envelope follower
MSP Tutorial 26: Frequency Domain Signal Processing with pfft~ MSP Tutorial 26: Frequency Domain Signal Processing with pfft~