mc.onepole~
Single-pole lowpass filter (multichannel)
Description
The onepole~ object implements the simplest of IIR filters, providing a 6dB per octave attenuation. This filter is very efficient and useful for gently rolling off harsh high end and for smoothing out control signals.
Discussion
The standard difference equation for this filter is
y(n) = a_{0} x(n) + b_{1} y(n-1)
Where
b_{1} = 1 - a_{0}
which can be factored down to
y(n) = y(n-1) + a_{0}[ x(n) - y(n-1) ]
As the value of the a_{0} coefficient is lowered (b_{1} increases) the input will be increasingly smoothed and the effective cutoff frequency (f_c) lowered. Calculating the a_0 coefficient from the f_c cutoff frequency is performed with the equation
a_{0} = sin(f_c * (pi/nyquist))
where f_s is the sampling frequency and f_c the cutoff frequency expressed in Hertz. onepole~ is a more efficient implementation of a biquad~ object with the following coefficients:
a_{0} &= a_{0}
a_{1} &= 0
a_{2} &= 0
b_{1} &= -b_{1}
b_{2} &= 0
Note the sign flip for b_{1} as biquad uses flipped signs for the feedback coefficients.
Arguments
center-frequency[float]hz
optional
Sets the center frequency for the filter, as described above.
Hz/linear/radians[symbol]
optional
Using the symbols
, , or for an optional second argument sets the frequency input mode. The default mode is Hz (which is the same as providing no mode argument). Using the argument sets the frequency input mode to linear (0 - 1). Using the argument sets the frequency input mode to radians (0 - 1).Attributes
Multichannel Group Attributes
chans[int]
The chans attribute sets the number of channels and instances in the MC wrapper object. To define a fixed number of channels regardless of what is connected to the object, set chans via a typed-in argument, for example typing 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). If an object does not have any multichannel signals connected to its inlets, 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 change 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.
initialvalues[list]
The initialvalues attribute only applies to object creation time so it must be set via a typed-in argument. initialvalues sets the first (and only the first) initial argument for successive instances in the MC wrapper. For example, typing 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 initialvalues does not determine the actual instance count; this can be done using the chans attribute. If there are more instances than elements for the initialvalues attribute, those instances are instantiated with the default value.
To set a default value of an argument for all instances, type it as an argument before any typed-in attributes. For example, modifying our example above: . 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 , , or messages.
values[list]
You can use values as an alternate name for the initialvalues attribute.
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 an 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 message instead of the target attribute. The voice index of 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. Note that target only affects messages, not setting attribute values.
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). For brevity the name bz can also be used.
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. For brevity the name @bzname can also be used.
op[symbol]
Sets the function that will be used when the attrui set to edit the op attribute, you can see a handy menu of the 40+ possible functions, so you don't have to memorize their names.
message is set. If you use
voiceprob[float]
The voiceprob attribute is used when employing the $ or * arguments to the message. It determines the probability that the message will be sent. For example, if voiceprob is 0.9, there is a 90% chance the setvalue message will be sent to a randomly chosen voice.
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]: 0
Adds or removes the object from the patcher's background layer.
adds the object to the background layer, 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'
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]: 0
Toggles whether an object ignores mouse clicks in a locked patcher.
jspainterfile[symbol]
JS Painter File
patching_rect[4 floats]: 0. 0. 100. 0.
Sets the position and size of the object in the patcher window.
position[2 floats]
write-only
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]: 0
Sets whether an object belongs to the patcher's presentation.
presentation_rect[4 floats]: 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]
write-only
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]
write-only
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
In right inlet: Sets the frequency for the filter (if no signal is connected). By default, frequency is expressed in Hz, where the allowable range is from 0 to one fourth of the current sampling rate. For convenience, onepole~ has two additional input modes that use the more conventional input range, 0 - 1 (see the and messages).
- center-frequency (Hz)
[int]
float
In right inlet: Sets the frequency for the filter (if no signal is connected). By default, frequency is expressed in Hz, where the allowable range is from 0 to one fourth of the current sampling rate. For convenience, onepole~ has two additional input modes that use the more conventional input range, 0 - 1 (see the and messages).
- center-frequency (Hz or 0 through 1 specified by object-argument)
[float]
Hz
In either inlet: Sets the frequency input mode to Hz (the default).
clear
In either inlet: Clears the internal state of onepole~. Since onepole~ does not have the inherent instability of other filter types, this should never be necessary.
linear
In either 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 traverses the full frequency range.
radians
In either inlet: Sets the frequency input mode to radians (0 - 1). Radians mode lets you set the center frequency (f_c) of the equation 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 right inlet: A signal can be used to set the frequency for the filter, with the same effect as a float. If a signal is connected to this inlet, its value is sampled once every signal vector.
Multichannel Group Messages
deviate
Generate a random value for each channel around a center value. An optional number after the center value specifies the upper range size so it can be different from the lower range size.
Example: will generate random values for the cutoff attribute of the objects in the wrapper centered around 1000 Hz (between 900 and 1100 Hz). sends messages to the objects in the wrapper with random values between 900 and 1200.
If no message name is provided, a message is used by default.
- range
[float]
- message-name
[symbol]
- center-value
[float]
- upper-range
[float]
exponential
The
K * exp(-1 * N * channel) where channel starts at 0 for the first channel.
If the second argument is not present the default value is 1. Example: would generate, for four channels, values of 10, 3.678, 1.353, and 0.498. would generate 2, 5.437, 14.78, and 40.17.
If no message name is provided, a message is used by default.
- exponent
[float]
- message-name
[symbol]
- multiplier
[float]
scaledexponential
The
K * exp(-1 * N * (channel / num_channels) where channel starts at 0 for the first channel.
If the second argument is not present the default value is 1. Example: would generate, for six channels, values of 2, 2.363, 2.791, 3.297, 3.895, 4.602. for four channels would generate 2, 2.568, 3.297, 4.324. provides a way to keep the range of the exponential series roughly the same independent of the number of channels.
If no message name is provided, a message is used by default.
- exponent
[float]
- message-name
[symbol]
- base
[float]
increment
The
Example: for four channels would generate 2, 7, 12, and 17.
If no message name is provided, a message is used by default.
- increment-amount
[float]
- message-name
[symbol]
- start-value
[float]
harmonic
The
F * (1 + N * channel) where channel starts at 0 for the first channel.
Example: for five channels would generate 440, 880, 1320, 1760, and 2200. for
four channels would generate 440, 660, 880, and 1100.
If no message name is provided, a message is used by default.
- multiplier
[float]
- message-name
[symbol]
- fundamental
[float]
subharmonic
The
F / (1 + N * channel) where channel starts at 0 for the first channel.
Example: for five channels would generate 440, 220, 146.7, and 110.
If no message name is provided, a message is used by default.
- multiplier
[float]
- message-name
[symbol]
- fundamental
[float]
spread
The
Example: for four channels would generate 0, 2.5, 5, and 7.5.
If no message name is provided, a message is used by default.
- boundary-value
[float]
- message-name
[symbol]
- other-boundary-value
[float]
spreadinclusive
The
Example: for four channels would generate 0, 3.33, 6.66, and 10.
If no message name is provided, a message is used by default.
- boundary-value
[float]
- message-name
[symbol]
- other-boundary-value
[float]
spreadexclusive
The
Example: for four channels would generate 2, 4, 6, and 8.
If no message name is provided, a message is used by default.
- boundary-value
[float]
- message-name
[symbol]
- other-boundary-value
[float]
spreadincludefirst
The
Example: for four channels would generate 0, 2.5, 5, and 7.5.
If no message name is provided, a message is used by default.
- boundary-value
[float]
- message-name
[symbol]
- other-boundary-value
[float]
spreadincludesecond
The
Example: for four channels would generate 2.5, 5, 7.5, and 10.
If no message name is provided, a message is used by default.
- boundary-value
[float]
- message-name
[symbol]
- other-boundary-value
[float]
decide
The
Example: for four channels would generate 0, 0, 0, 0 because the probability of generating a 1 is zero. could generate 10, 0, 0, 10 if the randomly generated values exceeded 0.5 for the first and fourth channels.
If no message name is provided, a message is used by default.
- probability
[float]
- message-name
[symbol]
- value
[float]
randomrange
The
If no message name is provided, a message is used by default.
- low-value
[float]
- message-name
[symbol]
- high-value
[float]
generate
The op attribute. Arguments passed to will be given to the function that is called. Example: if op is set to , is the same as sending the message .
message runs the function whose name is stored in the- low-value
[float]
- message-name
[symbol]
- high-value
[float]
ease.linear
The MC wrapper provides access to the easing functions found in the Ease Package. These are accessed with message names consisting of
The messages generate an non-linear and inclusive range of values across the space of channels. When you use two number arguments, the first value will be the low end of the range and the second will be the high end of the range. For and functions, this means the low end value will be set for the first channel and the high end will be set for the last channel. For function variants, the high end will be set for the first channel and the low end will be set for the last channel.
When the messages are supplied with three numerical arguments, the first two specify the range as in the two-argument case, but the third argument, which will be constrained between 0 and 1, defines a mid point. Between the first channel and the channel closest to the mid point, the entire range of the function is applied. Between the mid point and the last channel, the range of the function is applied with the values reversed, creating a mirror image. The mirror image is exact when the third argument is 0.5, otherwise it will be biased toward 0 or 1. With a mid point of 1, the result is the same as if the third argument was not supplied at all. With a mid point of 0, the result is the same as if it was entirely reversed. In other words, it's as if the version of the function were used instead of the version that was originally specified -- or vice versa.
Available messages are: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , and . Refer to the Ease Package documentation for details on these functions and demonstrations of their behavior.
If no message name is provided, a message is used by default.
- low-value
[float]
- message-name
[symbol]
- high-value
[float]
- mid-point
[float]
smoothstep
The
If no message name is provided, a message is used by default.
- low-value
[float]
- message-name
[symbol]
- high-value
[float]
- mid-point
[float]
setvalue
The word
Instead of a number, the message can also take a symbol indicating that the target channel index should be randomly chosen:
- urn object). Before chosing a channel, will also decide whether to send the message according to the current value of the voiceprob attribute. If voiceprob is 0.1, there is a 10% chance of sending the message. If voiceprob is 0.9, there is a 90% chance of sending the message. will choose a channel randomly but avoid duplicate choices until all channels have been chosen (similar to the Max
- urn object). Unlike it will always send the message. will choose a channel randomly but avoid duplicate choices until all channels have been chosen (similar to the Max
- random object). Before chosing a channel, will also decide whether to send the message according to the current value of the voiceprob attribute. If voiceprob is 0.1, there is a 10% chance of sending the message. If voiceprob is 0.9, there is a 90% chance of sending the message. will choose a channel randomly (similar to the Max
- random object). Unlike it will always send the message. will choose a channel randomly (similar to the Max
- channel
[int]
- message
[symbol]
- message arguments
[list]
setvaluerange
The word
Example: , sends the message 50 to channels 1 - 4. If the second argument is -1, the message is sent to all subsequent channels. For example, sends the message 50 to all channels between 2 and the current number of voices.
Note: the random channel selection feature using , , , and does not work with the message.
- low channel
[int]
- high channel
[int]
- message
[symbol]
- message arguments
[list]
applymessages
The word
, followed by one or more numbers and/or symbols, sends individual messages successively to instances in the MC wrapper, starting with the first instance. For example, the message will send the '0' message to the first instance, and the 'bang' message to the second instance. If there are more instances than arguments to , the extra instances are unaffected.- messages
[list]
applyvalues
The word
, 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 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 , the extra instances are unaffected.- message-name
[symbol]
- values
[list]
replicatevalues
The word
, 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 , the message continues sending values to successive instances, restarting with the first element, if it runs out of arguments to send. For example, 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.- message-name
[symbol]
- values
[list]
applynvalues
Whereas wave~ to set start/end points. The message syntax is [applynvalues N value1, value2 etc.] where N is the number of values to set for each instance. For example, the message will send 500 600 to the first instance and 900 1000 to the second instance. If there are more instances than specified in , the extra instances are unaffected.
can only set one value, the message permits sending a message or setting an attribute with multiple values to instances in the MC wrapper, starting with the first instance. This is helpful for messages that require multiple values, such as the list message to- message
[int]
- values
[list]
replicatenvalues
Whereas wave~ to set start/end points. The message syntax is [replicatenvalues N value1, value2 etc.] where N is the number of values to set for each instance. Unlike , the message continues sending values to successive instances, restarting with the first group, if it runs out of arguments to send. For example, to an MC wrapper object with three instances will send 500 600 to the first instance, 900 1000 to the second instance, and 500 600 to the third instance.
can only set one value, the message permits sending a message or setting an attribute with multiple values to instances in the MC wrapper, starting with the first instance. This is helpful for messages that require multiple values, such as the list message to- message
[int]
- values
[list]
Output
signal
The filtered signal.
See Also
Name | Description |
---|---|
biquad~ | Two-pole, two-zero filter |
comb~ | Apply a comb filter effect |
cross~ | Third-order crossover filter |
lores~ | Resonant lowpass filter |
reson~ | Resonant bandpass filter |
svf~ | State-variable filter with simultaneous outputs |