mirror of
https://github.com/thestk/stk
synced 2026-01-11 03:51:53 +00:00
123 lines
4.1 KiB
C++
123 lines
4.1 KiB
C++
/***************************************************/
|
|
/*! \class Filter
|
|
\brief STK filter class.
|
|
|
|
This class implements a generic structure that
|
|
can be used to create a wide range of filters.
|
|
It can function independently or be subclassed
|
|
to provide more specific controls based on a
|
|
particular filter type.
|
|
|
|
In particular, this class implements the standard
|
|
difference equation:
|
|
|
|
a[0]*y[n] = b[0]*x[n] + ... + b[nb]*x[n-nb] -
|
|
a[1]*y[n-1] - ... - a[na]*y[n-na]
|
|
|
|
If a[0] is not equal to 1, the filter coeffcients
|
|
are normalized by a[0].
|
|
|
|
The \e gain parameter is applied at the filter
|
|
input and does not affect the coefficient values.
|
|
The default gain value is 1.0. This structure
|
|
results in one extra multiply per computed sample,
|
|
but allows easy control of the overall filter gain.
|
|
|
|
by Perry R. Cook and Gary P. Scavone, 1995 - 2005.
|
|
*/
|
|
/***************************************************/
|
|
|
|
#ifndef STK_FILTER_H
|
|
#define STK_FILTER_H
|
|
|
|
#include "Stk.h"
|
|
#include <vector>
|
|
|
|
class Filter : public Stk
|
|
{
|
|
public:
|
|
//! Default constructor creates a zero-order pass-through "filter".
|
|
Filter(void);
|
|
|
|
//! Overloaded constructor which takes filter coefficients.
|
|
/*!
|
|
An StkError can be thrown if either of the coefficient vector
|
|
sizes is zero, or if the a[0] coefficient is equal to zero.
|
|
*/
|
|
Filter( std::vector<StkFloat> &bCoefficients, std::vector<StkFloat> &aCoefficients );
|
|
|
|
//! Class destructor.
|
|
virtual ~Filter(void);
|
|
|
|
//! Sets all internal states of the filter to zero.
|
|
void clear(void);
|
|
|
|
//! Set filter coefficients.
|
|
/*!
|
|
An StkError can be thrown if either of the coefficient vector
|
|
sizes is zero, or if the a[0] coefficient is equal to zero. If
|
|
a[0] is not equal to 1, the filter coeffcients are normalized by
|
|
a[0]. The internal state of the filter is not cleared unless the
|
|
\e clearState flag is \c true.
|
|
*/
|
|
void setCoefficients( std::vector<StkFloat> &bCoefficients, std::vector<StkFloat> &aCoefficients, bool clearState = false );
|
|
|
|
//! Set numerator coefficients.
|
|
/*!
|
|
An StkError can be thrown if coefficient vector is empty. Any
|
|
previously set denominator coefficients are left unaffected. Note
|
|
that the default constructor sets the single denominator
|
|
coefficient a[0] to 1.0. The internal state of the filter is not
|
|
cleared unless the \e clearState flag is \c true.
|
|
*/
|
|
void setNumerator( std::vector<StkFloat> &bCoefficients, bool clearState = false );
|
|
|
|
//! Set denominator coefficients.
|
|
/*!
|
|
An StkError can be thrown if the coefficient vector is empty or
|
|
if the a[0] coefficient is equal to zero. Previously set
|
|
numerator coefficients are unaffected unless a[0] is not equal to
|
|
1, in which case all coeffcients are normalized by a[0]. Note
|
|
that the default constructor sets the single numerator coefficient
|
|
b[0] to 1.0. The internal state of the filter is not cleared
|
|
unless the \e clearState flag is \c true.
|
|
*/
|
|
void setDenominator( std::vector<StkFloat> &aCoefficients, bool clearState = false );
|
|
|
|
//! 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.
|
|
*/
|
|
virtual void setGain(StkFloat gain);
|
|
|
|
//! Return the current filter gain.
|
|
virtual StkFloat getGain(void) const;
|
|
|
|
//! Return the last computed output value.
|
|
virtual StkFloat lastOut(void) const;
|
|
|
|
//! Input one sample to the filter and return one output.
|
|
virtual StkFloat tick( StkFloat input );
|
|
|
|
//! Take a channel of the StkFrames object as inputs to the filter and replace with corresponding outputs.
|
|
/*!
|
|
The \c channel argument should be zero or greater (the first
|
|
channel is specified by 0). An StkError will be thrown if the \c
|
|
channel argument is equal to or greater than the number of
|
|
channels in the StkFrames object.
|
|
*/
|
|
virtual StkFrames& tick( StkFrames& frames, unsigned int channel = 0 );
|
|
|
|
protected:
|
|
|
|
StkFloat gain_;
|
|
std::vector<StkFloat> b_;
|
|
std::vector<StkFloat> a_;
|
|
std::vector<StkFloat> outputs_;
|
|
std::vector<StkFloat> inputs_;
|
|
|
|
};
|
|
|
|
#endif
|