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#include <TwoPole.h>
Inheritance diagram for TwoPole:
This protected Filter subclass implements a two-pole digital filter. A method is provided for creating a resonance in the frequency response while maintaining a nearly constant filter gain.
by Perry R. Cook and Gary P. Scavone, 1995 - 2007.
Public Member Functions | |
TwoPole () | |
Default constructor creates a second-order pass-through filter. | |
~TwoPole () | |
Class destructor. | |
void | ignoreSampleRateChange (bool ignore=true) |
A function to enable/disable the automatic updating of class data when the STK sample rate changes. | |
void | clear (void) |
Clears the internal states of the filter. | |
void | setB0 (StkFloat b0) |
Set the b[0] coefficient value. | |
void | setA1 (StkFloat a1) |
Set the a[1] coefficient value. | |
void | setA2 (StkFloat a2) |
Set the a[2] coefficient value. | |
void | setResonance (StkFloat frequency, StkFloat radius, bool normalize=false) |
Sets the filter coefficients for a resonance at frequency (in Hz). | |
void | setGain (StkFloat gain) |
Set the filter gain. | |
StkFloat | getGain (void) const |
Return the current filter gain. | |
StkFloat | lastOut (void) const |
Return the last computed output value. | |
StkFloat | tick (StkFloat sample) |
Input one sample to the filter and return one output. | |
StkFrames & | tick (StkFrames &frames, unsigned int channel=0) |
Take a channel of the StkFrames object as inputs to the filter and replace with corresponding outputs. |
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Sets the filter coefficients for a resonance at frequency (in Hz). This method determines the filter coefficients corresponding to two complex-conjugate poles with the given frequency (in Hz) and radius from the z-plane origin. If normalize is true, the coefficients are then normalized to produce unity gain at frequency (the actual maximum filter gain tends to be slightly greater than unity when radius is not close to one). The resulting filter frequency response has a resonance at the given frequency. The closer the poles are to the unit-circle (radius close to one), the narrower the resulting resonance width. An unstable filter will result for radius >= 1.0. For a better resonance filter, use a BiQuad filter.
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Set the filter gain. The gain is applied at the filter input and does not affect the coefficient values. The default gain value is 1.0. Reimplemented from Filter. |
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Take a channel of the StkFrames object as inputs to the filter and replace with corresponding outputs.
The Reimplemented from Filter. |
The Synthesis ToolKit in C++ (STK) |
©1995-2007 Perry R. Cook and Gary P. Scavone. All Rights Reserved. |