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https://github.com/thestk/stk
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81 lines
2.4 KiB
C++
81 lines
2.4 KiB
C++
/***************************************************/
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/*! \class TwoZero
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\brief STK two-zero filter class.
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This protected Filter subclass implements
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a two-zero digital filter. A method is
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provided for creating a "notch" in the
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frequency response while maintaining a
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constant filter gain.
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by Perry R. Cook and Gary P. Scavone, 1995 - 2005.
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*/
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/***************************************************/
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#ifndef STK_TWOZERO_H
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#define STK_TWOZERO_H
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#include "Filter.h"
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class TwoZero : protected Filter
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{
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public:
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//! Default constructor creates a second-order pass-through filter.
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TwoZero();
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//! Class destructor.
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~TwoZero();
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//! Clears the internal states of the filter.
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void clear(void);
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//! Set the b[0] coefficient value.
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void setB0(StkFloat b0);
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//! Set the b[1] coefficient value.
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void setB1(StkFloat b1);
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//! Set the b[2] coefficient value.
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void setB2(StkFloat b2);
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//! Sets the filter coefficients for a "notch" at \e frequency (in Hz).
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/*!
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This method determines the filter coefficients corresponding to
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two complex-conjugate zeros with the given \e frequency (in Hz)
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and \e radius from the z-plane origin. The coefficients are then
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normalized to produce a maximum filter gain of one (independent of
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the filter \e gain parameter). The resulting filter frequency
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response has a "notch" or anti-resonance at the given \e
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frequency. The closer the zeros are to the unit-circle (\e radius
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close to or equal to one), the narrower the resulting notch width.
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*/
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void setNotch(StkFloat frequency, StkFloat radius);
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//! Set the filter gain.
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/*!
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The gain is applied at the filter input and does not affect the
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coefficient values. The default gain value is 1.0.
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*/
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void setGain(StkFloat gain);
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//! Return the current filter gain.
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StkFloat getGain(void) const;
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//! Return the last computed output value.
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StkFloat lastOut(void) const;
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//! Input one sample to the filter and return one output.
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StkFloat tick(StkFloat sample);
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//! Take a channel of the StkFrames object as inputs to the filter and replace with corresponding outputs.
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/*!
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The \c channel argument should be zero or greater (the first
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channel is specified by 0). An StkError will be thrown if the \c
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channel argument is equal to or greater than the number of
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channels in the StkFrames object.
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*/
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StkFrames& tick( StkFrames& frames, unsigned int channel = 0 );
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};
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#endif
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