mc.pfft~

Spectral processing manager for patchers (multichannel)

Description

The pfft~ object is designed to simplify spectral audio processing using the Fast Fourier Transform (FFT). In addition to performing the FFT and the Inverse Fast Fourier Transform (IFFT), pfft~ (with the help of its companion fftin~ and fftout~ objects) manages the necessary signal windowing, overlapping and adding needed to create a real-time Short Term Fourier Transform (STFT) analysis/resynthesis system.

Discussion

The number of inlets on the pfft~ object is determined by the number of fftin~ and/or in objects in the enclosed subpatch. Patchers loaded into a pfft~ object can only be given signal inlets by fftin~ objects within the patch. See fftin~ and in for details.

Arguments

subpatch-name [symbol]

Name of patcher to load

FFT-size [int]

Optional
Unitssamples

Specifies the FFT size, in samples, of the overlapped windows which are transformed to and from the spectral domain by the FFT/IFFT. The window size must be a power of 2, and defaults to 512. (Note: The size of the spectral "frames" processed by the pfft~ object's subpatch will be half this size, as the 2nd half of the spectrum is a mirror of the first and thus redundant, unless the full-spectrum-flag is present.)

overlap-factor (hop-size-denominator) [int]

Optional

The third argument determines the overlap factor for FFT analysis and resynthesis windows. The hop size (number of samples between each successive FFT window) of Fast Fourier transforms performed is equal to the size of the Fast Fourier transform divided by this overlap factor. (e.g. if the frame size is 512 and the overlap is set to 4 then the hop size is 128 samples). The value must be a power of 2 and defaults to 2. A value of 4 is recommended for most applications.

start-onset [int]

Optional
Unitssamples

The fourth argument specifies the start onset in samples for the Fast Fourier transform. It must be a multiple of the current signal vector size and defaults to 0.

full-spectrum-flag (0 or nonzero) [int]

Optional

A non-zero fifth argument may be used to specify "full-spectrum mode". In this mode, the pfft~ object will internally compute a complex FFT and process full DC to SR mirrored spectra (instead of simply eliminating the redundant half of the spectrum). This takes extra computing power but may be potentially useful in some of the more esoteric spectral processing applications.

'args' and list-of-argument-values [symbol]

Optional

Use the argument args followed by an argument value to initialize any pound-sign arguments in the loaded patcher (e.g., args #1). If used, the args argument must be the last argument word used; everything which appears after the word args will be treated as an argument value.

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]

Sets the justification for the object's text.

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.

Multichannel Group Attributes

chans [int]

The chans attribute sets the number of channels and instances in the MC wrapper object. If you want a fixed number of channels regardless of what is connected to the object, you could set chans via a typed-in argument, for example typing mc.cycle~ @chans 100 would create 100 instances of a cycle~ object inside the MC wrapper. If chans is 0, the wrapper object will auto-adapt to the number of channels in its input multichannel signals (using the maximum of all connected signals). For objects without connected multichannel signals, the chans attribute will need to have a non-zero value if you want more than one instance.

If chans is changed while the audio is on, the number of instances will not updated until audio is restarted. However, if chans is reduced while the audio is on, any extra channels will no longer process audio and will output a zero signal.

values [int]

The values attribute only applies to object creation time so it must be set via typed-in argument syntax. values sets the first (and only the first) initial argument for successive instances in the MC wrapper. For example, typing mc.cycle~ @chans 4 @values 50 60 70 80 would assign an initial frequency to the cycle~ instances inside the wrapper. The first instance would be assigned a frequency of 50, the second a frequency of 60, the third 70, and the fourth 80. Note that values does not determine the actual instance count; this can be done using the chans attribute. If there are more instances than elements for the values attribute, those instances are instantiated with the default value.

If you want to set a default initial value for all instances, simply type it as an argument before any typed-in attributes. For example, modifying our example above: mc.cycle~ 100 @chans 10 @values 50 60 70 80. In this example, the first four instances are set as before, but the next six are created with a frequency argument of 100.

To change instance values or attributes after the wrapper object has been created, use the setvalue, applyvalues, or replicatevalues messages.

replicate [int]

When replicate is enabled, input single-channel or multichannel signals containing fewer channels than the number instances in the MC wrapper object are repeated to fill all input channels. For example, when replicate is enabled and you connect a two-channel multichannel signal to the input of an MC wrapper object with four instances, channel 1 of the input will be repeated to channel 3, and channel 2 of the input will be repeated to channel 4. If replicate were disabled, channels 3 and 4 of the input would be set to zero.

target [int]

The target attribute sets a voice index for targeting specific wrapper instances. Subsequent messages are directed to an individual instance instead of all instances. It is strongly recommended you use the more reliable setvalue message instead of the target attribute. The voice index of setvalue will override the current setting of target. When target is 0, incoming messages are sent to all instances. When target is -1, incoming messages do nothing.

usebusymap [int]

When usebusymap is enabled, the MC wrapper controls whether individual instances process audio using a busy map maintained by either an mc.noteallocator~ or mc.voiceallocator~ object. When a channel in the busy map is marked as "free" or "released" no audio processing occurs by any instance on the channel corresponding to the voice index. When usebusymap is disabled, instances in the MC wrapper process audio at all times. This will also be true if usebusymap is enabled and there is no local or named busy map available. (See the busymapname attribute for a description of local and named busy maps).

zero [int]

When the zero attribute is enabled, channels in the MC wrapper due to the use of a busy map output zero signals. To save a small amount of CPU at the risk of loud and unpleasant noises due to uncleared signal data, you can disable zero. In this case, disabled channels in the MC wrapper do nothing to their output channels. If usebusymap is disabled or there is no active local or named busy map available, the setting of the zero attribute has no effect.

Conveniently, when usebusymap is enabled in mc.mixdown~ object, disabled channels are not mixed to the output. When unused signals from wrapped objects with zero disabled feed into mc.mixdown~, they will be ignored, reducing the risk of unpleasantness getting past the mix output.

busymapname [symbol]

When the usebusymap attribute is enabled, an MC wrapper object uses the local busy map of any mc.voiceallocator~ or mc.noteallocator~ in the same patcher by default. To use a named global busy map instead, set the busymapname attribute to the desired name.

Messages

bang

Patchers loaded into a pfft~ object can only accept bang messages by in objects within the patch. The number of inputs is determined by the in objects in the enclosed subpatch. See in for details.

int

Arguments

input [int]
Integer values sent to the pfft~ object cause the object to act according to the user-defined functionality within it.

float

Arguments

input [float]
Floating-point values sent to the pfft~ object cause the object to act according to the user-defined functionality within it.

list

Arguments

input [list]
Lists sent to the pfft~ object cause the object to act according to the user-defined functionality within it.

anything

Arguments

input [list]
Messages sent to the pfft~ object cause the object to act according to the user-defined functionality within it.

clear

Clears all of the pfft~ object's internal buffers.

(mouse)

Double-clicking with the mouse on the pfft~ object opens a Max patcher window containing the patcher loaded by the object.

mute

Arguments

mute-flag (0 or 1) [int]
The word mute, followed by a 1 or 0, will mute or unmute the pfft~, turning off signal processing within the enclosed subpatch.

open

Arguments

subpatch-filename [int]
The word open will open the subpatch loaded into the pfft~ object.

wclose

Arguments

subpatch-filename [int]
Closes the enclosed subpatch if it is open.

Multichannel Group Messages

deviate

Arguments

range [float]
message-name [symbol]
center-value [float]
Generate a random value for each channel around a center value. If no message name is provided then a float message is used by default.

exponential

Arguments

exponent [float]
base [float]
The exponential message generates an exponential series using the second argument as a base and the first argument as an exponent.

scaledexponential

Arguments

exponent [float]
base [float]
The scaledexponential message generates an exponential series using the second argument as a base and the first argument as an exponent. Values are scaled by the instance number, so the total range of the series is independent of the number of channels.

increment

Arguments

increment-amount [float]
message-name [symbol]
start-value [float]
Generate a increasing value for each channel starting at a specified value. If no message name is provided then a float message is used by default.

harmonic

Arguments

multiplier [float]
fundamental [float]
The harmonic message generate a harmonic series using the second argument as the fundamental frequency and the first argument as a multiplier.

subharmonic

Arguments

multiplier [float]
fundamental [float]
The subharmonic message generate a subharmonic series using the second argument as the fundamental frequency and the first argument as a multiplier.

spread

Arguments

boundary-value [float]
message-name [symbol]
other-boundary-value [float]
Generate a range of values distributed to each channel. If no message name is provided then a float message is used by default. The first boundary value is included in the range outputs, but the last boundary value is not.

spreadinclusive

Arguments

boundary-value [float]
message-name [symbol]
other-boundary-value [float]
Generate a range of values distributed to each channel. If no message name is provided then a float message is used by default. Both the first and last boundary values are included in the range outputs.

spreadexclusive

Arguments

boundary-value [float]
message-name [symbol]
other-boundary-value [float]
Generate a range of values distributed to each channel. If no message name is provided then a float message is used by default. Neither the first nor last boundary values are included in the range outputs.

spreadincludefirst

Arguments

boundary-value [float]
message-name [symbol]
other-boundary-value [float]
Generate a range of values distributed to each channel. If no message name is provided then a float message is used by default. The first boundary value is included in the range outputs, but the last boundary value is not. The spreadincludefirst message is the same as the spread message.

spreadincludesecond

Arguments

boundary-value [float]
message-name [symbol]
other-boundary-value [float]
Generate a range of values distributed to each channel. If no message name is provided then a float message is used by default. The first boundary value is not included in the range outputs, but the last boundary value is included.

setvalue

Arguments

channel [int]
message [symbol]
message arguments [list]
The word setvalue, followed by both a channel index (starting at 1) and any message that can be sent to the wrapped object, sends the message to an individual instance within the MC wrapper. setvalue 0, followed by a message, sends the message to all instances. The setvalue message can be used in any inlet.

applyvalues

Arguments

message-name [symbol]
values [list]
The word applyvalues, followed by an optional message name and one or more message arguments, sends individual values in the arguments successively to instances in the MC wrapper, starting with the first instance. For example, the message applyvalues 4 5 6 will send 4 to the first instance, 5 to the second instance, and 6 to the third instance. If there are more instances than arguments to applyvalues, the extra instances are unaffected.

replicatevalues

Arguments

message-name [symbol]
values [list]
The word replicatevalues, followed by an optional message name and one or more message arguments, sends individual values in the arguments successively to instances in the MC wrapper, starting with the first instance. Unlike applyvalues, the replicatevalues message continues sending values to successive instances, restarting with the first element, if it runs out of arguments to send. For example, replicatevalues 4 5 to an MC wrapper object with three instances will send 4 to the first instance, 5 to the second instance, and 4 to the third instance.

Output

message

Any messages received by an out object in a loaded patcher appear at the message outlet of the pfft~ object which corresponds to the number argument of the out object. The message outlets of a pfft~ object appear to the right of the rightmost signal outlet.

signal

The output is the result of the FFT-based signal processing subpatch. As with the fft~ and ifft~ objects, pfft~ introduces a slight delay from input to output (although it is less than half the delay than with an fft~ / ifft~ combination). The I/ O delay is equal to the window size minus the hop size (e.g., for a 1024-sample FFT window with an overlap factor of 4, the hop size is equal to 256, and the overall delay from input to output is 768 samples). The number of outlets is determined by the number of fftout~ and/or out objects in the loaded subpatcher. Patchers loaded into a pfft~ object can be given outlets by fftout~ or out objects within the patch. See fftout~ and out for details.

See Also

Name Description
cartopol Convert cartesian to polar coordinates
cartopol~ Signal Cartesian to Polar coordinate conversion
fft~ Fast Fourier transform
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
in Message input for a patcher loaded by poly~ or pfft~
out Message output for a patcher loaded by poly~ or pfft~
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
MSP Analysis Tutorial 4: Signal Processing with pfft~ MSP Analysis Tutorial 4: Signal Processing with pfft~