svf~

State-variable filter with simultaneous outputs

Description

The svf~ object is an implementation of a state-variable filter algorithm described in Hal Chamberlin's book, "Musical Applications of Microprocessors." A unique feature of this filter object is that it produces lowpass, highpass, bandpass, and bandreject (notch) output simultaneously - all four are available as outlets.

Examples

Four filter outputs are simultaneously available from the svf~ object

Arguments

center-frequency [float]

Optional
Unitshz

Sets the initial center frequency for the filter. The default value is 0.

resonance [float]

Optional

Sets the initial resonance value for the filter. The default value is 0.01.

Hz [symbol]

Optional

Sets the frequency input mode to Hz (the default mode - hence this is the same as providing no mode argument).

linear [symbol]

Optional

Sets the frequency input mode to linear (0 -1).

radians [symbol]

Optional

Sets the frequency input mode to radians (0 -1).

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.

jspainterfile [symbol]

JS Painter File

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 [4 floats]

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.

Messages

int

Arguments

center-frequency/resonance [int]
In middle and right inlets: Integer values are converted to floats and can be sent in the two right inlets to change the center frequency and resonance of the filter. By default, the center frequency is expressed in Hz, where the allowable range is from 0 to one quarter of the current sampling rate. If a signal is connected to one of the inlets, a number received in that inlet is ignored. The values are sampled once every signal vector.

float

Arguments

center-frequency/resonance [float]
In middle and right inlets: A float can be sent in the two right inlets to change the center frequency and resonance of the filter. By default, the center frequency is expressed in Hz, where the allowable range is from 0 to one quarter of the current sampling rate. For convenience, svf~ has two additional input modes that use the more conventional input range, 0 - 1. (see the linear and radians messages). If a signal is connected to one of the inlets, a number received in that inlet is ignored. The values are sampled once every signal vector.

Hz

In either inlet: Sets the frequency input mode to Hz (the default).

clear

Clears the object's sample-memory in case of a blow-up.

linear

In any inlet: Sets the frequency input mode to linear (0 - 1). Linear mode is simply a scaled version of the standard Hz mode, except that values in the 0-1 range traverse the full frequency range.

radians

In any inlet: Sets the frequency input mode to radians (0 - 1). Radians mode lets you set the center frequency directly -- while the input has the same range (0-1), the output has a curved frequency response that is closer to the exponential pitch scale of the human ear.

signal

In left inlet: Signal to be filtered.

In middle inlet: Sets the filter center frequency in Hz.

In right inlet: Sets the bandpass filter "Q" - roughly, the sharpness of the filter - where Q is defined as the filter bandwidth divided by the center frequency. Useful Q values are typically between 0.01 and 500.

Output

signal

The filtered input signal.

See Also

Name Description
Sound Processing Techniques Sound Processing Techniques
biquad~ Two-pole, two-zero filter
comb~ Apply a comb filter effect
cross~ Third-order crossover filter
onepole~ Single-pole lowpass filter
lores~ Resonant lowpass filter
reson~ Resonant bandpass filter
Audio Filtering Audio Filtering