Description
Use the filterdesign object to create a dictionary containing a specification for a filter that can be realized by several other objects including the cascade~ object.
Arguments
None.
Attributes
frequency [2 floats]
Filter cutoff frequencies specified in units defined by the units attribute. For lowpass and highpass filters a single frequency will be used to define the cutoff. For bandpass and bandstop filters two frequencies are required.
name [symbol]
Name to which the output dictionary is bound
order [int]
The order of the filter, which is to say the number of poles and zeroes. For reference, the biquad~ object is a second-order filter (2 poles and 2 zeroes).
passband_ripple [float]
Magnitude ripple in the passband for Chebyshev Type 1 filters in decibels. Higher amounts of ripple will provide a narrower transition band given a constant order for the filter.
response [symbol]
Filter response shape
Possible values:
'lowpass'
(
Low frequencies pass through, high frequencies are attenuated
)
'highpass'
(
High frequencies pass through, low frequencies are attenuated
)
'bandpass'
(
A band of frequencies pass through, low and high frequencies are attenuated
)
'bandstop'
(
A band of frequencies are attenuated, low and high frequencies pass through
)
samplerate [int]
Samplerate used when unit attribute is set to hertz. If the samplerate is set to zero then MSP's samplerate will be used.
sos_output [int]
Inclusion of coefficients for second-order-sections in the output dictionary. This is the native format used by cascade~, zplane~, and filtergraph~.
stopband_attenuation [float]
Minimum attenuation in Chebyshev Type 2 filter stopband in decibels. For given order of filter, greater attenuation results in a wider transition band and less attenuation in the stopband results in a narrower transition band.
tf_output [int]
Include single-section transfer function coefficients in the output dictionary. This representation works well for low-ordered filters but quickly becomes subject to floating-point precision roundoff as the order of the filter increases.
topology [symbol]
The organization of the zeroes and poles used to realize the filter.
Possible values:
'butterworth'
(
Gentle transition, flat passband, monotonically decreasing stopband
)
'chebyshev-1'
(
Steepest transition, definable ripple in passband, monotonically decreasing stopband
)
'chebyshev-2'
(
Moderate transition, flat passband, definable ripple in the stopband
)
units [symbol]
Units of measurement for specifying frequencies
Possible values:
'hertz'
(
Cycles per second, based on the
samplerate
attribute
)
'normalized'
(
Range from 0.0 to 1.0; 1.0 is the nyquist frequency
)
'radians'
(
Range from 0.0 to pi; pi is the nyquist frequency
)
zpk_output [int]
Include zeroes-poles-gain representation in the output dictionary. Zeroes-poles-gain (ZPK) provides a more accurate representation of the filter's response than the single-section transfer function (see tf_output attribute) for higher-order filters. If calculating coefficients for second-order-sections (see sos_output attribute) the ZPK representation is calculated as an intermediary stage.
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]
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]
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]
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]
Text Justification
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
bang
(mouse)
Output
dictionary
A filterdesign dictionary containing the specified filter characteristics.
See Also
| Name | Description |
|---|---|
| Sound Processing Techniques | Sound Processing Techniques |
| filterdetail | Detail the characteristics of a filter |
| plot~ | Visualize two-dimensional data |
| cascade~ | Cascaded series of biquad filters |
| Audio Filtering | Audio Filtering |