filterdesign
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.
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'
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]
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 [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
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 |