mc.biquad~

Two-pole, two-zero filter (multichannel)

Description

biquad~ implements a two-pole, two-zero filter using the following equation:

y[n] = a0 * x[n] + a1 * x[n-1] + a2 * x[n-2] - b1 * y[n-1] - b2 * y[n-2]

You can specify the coefficients a0, a1, a2, b1, and b2 as signals or floats (if you make the filter explode by making the b coefficients too high, you can recover (after lowering them) with the clear message, or by turning the audio on and off).

Arguments

a0 [float]

Set the initial value for the a0 filter coefficient. If a signal is connected to the second inlet, the coefficient supplied as an argument is ignored.

a1 [float]

Set the initial value for the a1 filter coefficient. If a signal is connected to the third inlet, the coefficient supplied as an argument is ignored.

a2 [float]

Set the initial value for the a2 filter coefficient. If a signal is connected to the fourth inlet, the coefficient supplied as an argument is ignored.

b1 [float]

Set the initial value for the b1 filter coefficient. If a signal is connected to the fifth inlet, the coefficient supplied as an argument is ignored.

b2 [float]

Set the initial value for the b2 filter coefficient. If a signal is connected to the sixth inlet, the coefficient supplied as an argument is ignored.

Attributes

smooth [int] (default: 1)

Toggles the smoothing of filter coeffient changes.

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

int

Arguments

filter-coefficient [int]
Converted to float.

The coefficients in inlets 2 to 6 may be specified by a number instead of a signal. If a signal is also connected to the inlet, the number value is ignored.

float

Arguments

filter-coefficient [float]
The coefficients in inlets 2 to 6 may be specified by a float instead of a signal. If a signal is also connected to the inlet, the float is ignored.

list

Arguments

a0 [float]
a1 [float]
a2 [float]
b1 [float]
b2 [float]
The five filter coefficients can be provided as a list in the left inlet. The first number in the list is coefficient a0, the next is a1, and so on. If a signal is connected to a given inlet, the coefficient supplied in the list for that inlet is ignored.

clear

Clears the biquad~ object's memory of previous inputs and outputs, resetting xn-1, xn-2, yn-1, and yn-2 to 0.

dictionary

Arguments

dictionary-name [symbol]
The word dictionary, followed by a symbol that references a named filterdesign object dictionary (set via the name attribute), will cause the biquad~ object to use the dictionary values for filter coefficients.

signal

In left inlet: Signal to be filtered. The filter mixes the current input sample with the two previous input samples and the two previous output samples according to the formula:

yn = a0xn + a1xn-1 + a2xn-2 - b1yn-1 - b2yn-2.

In 2nd inlet: Amplitude coefficient a0, for scaling the amount of the current input to be passed directly to the output.

In 3rd inlet: Amplitude coefficient a1, for scaling the amount of the previous input sample to be added to the output.

In 4th inlet: Amplitude coefficient a2, for scaling the amount of input sample n-2 to be added to the output.

In 5th inlet: Amplitude coefficient b1, for scaling the amount of the previous output sample to be added to the current output.

In right inlet: Amplitude coefficient b2, for scaling the amount of output sample n-2 to be added to the current output. .

stoke

Arguments

a0 [float]
a1 [float]
a2 [float]
b1 [float]
b2 [float]
The word stoke, followed by a list that specifies a set of filter coefficient values, will preload the filter so that it starts in a given initial state, allowing the filter to be used for purposes such as a ringing oscillator.

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

signal

The filtered signal.

See Also

Name Description
buffir~ buffer-based FIR filter
cascade~ Cascaded series of biquad filters
comb~ Apply a comb filter effect
cross~ Third-order crossover filter
filtergraph~ Filter editor
lores~ Resonant lowpass filter
onepole~ Single-pole lowpass filter
reson~ Resonant bandpass filter
svf~ State-variable filter with simultaneous outputs
teeth~ Comb filter with feedforward and feedback delay control
Audio Filtering Audio Filtering