avir::CDSPFracFilterBankLin< fptype > Class Template Reference

Sinc function-based fractional delay filter bank. More...

#include <avir.h>

Public Member Functions
int	calcInitComplexity (const CBuffer< char > &FracUseMap) const
	Returns an approximate initialization complexity, expressed in the number of multiply-add operations.
void	copyInitParams (const CDSPFracFilterBankLin &s)
	Copies a limited set of parameters of the source filter bank.
void	createAllFilters ()
	Makes sure all fractional delay filters were created.
const fptype *	getFilter (const int i)
	Returns the pointer to the specified interpolation table filter.
const fptype *	getFilterConst (const int i) const
	Returns the pointer to the specified interpolation table filter.
int	getFilterLen () const
	Returns the length of each fractional delay filter, in samples (taps). Always an even value.
int	getFracCount () const
	Returns the number of fractional filters in use by this bank.
int	getOrder () const
	Returns the order of the interpolation polynomial.
void	init (const int ReqFracCount, const int ReqOrder, const double BaseLen, const double Cutoff, const double aWFAlpha, const CFltBuffer &aExtFilter, const int aAlignment=0, const int FltLenAlign=1)
	Initializes (builds) the filter bank based on the supplied parameters.
bool	operator== (const CDSPFracFilterBankLin &s) const
	Compares this filter bank and another filter bank, and returns true, if their parameters are equal. Alignment is not taken into account.

Detailed Description

template<typename fptype>
class avir::CDSPFracFilterBankLin< fptype >

Sinc function-based fractional delay filter bank.

Class implements storage and initialization of a bank of sinc function-based fractional delay filters, expressed as 1st order polynomial interpolation coefficients. The filters are produced from a single "long" windowed low-pass filter. Also supports 0th-order ("nearest neighbor") interpolation.

This class also supports multiplication of each fractional delay filter by an external filter (usually a low-pass filter).

Template Parameters

fptype

Specifies storage type of the filter coefficients bank. The filters are initially calculated using the "double" precision.

Member Function Documentation

calcInitComplexity()

template<typename fptype>

int avir::CDSPFracFilterBankLin< fptype >::calcInitComplexity

(

const CBuffer< char > &

FracUseMap

)

const

Returns an approximate initialization complexity, expressed in the number of multiply-add operations.

This includes fractional delay filters calculation and multiplication by an external filter. This function can only be called after the init() function.

Parameters

FracUseMap

Fractional delays use map, each element corresponds to a single fractional delay, will be compared to the internal table fill flags. This map should include 0 and 1 values only.

Returns

The complexity of the initialization, expressed in the number of multiply-add operations.

copyInitParams()

template<typename fptype>

void avir::CDSPFracFilterBankLin< fptype >::copyInitParams

(

const CDSPFracFilterBankLin< fptype > &

s

)

Copies a limited set of parameters of the source filter bank.

The actual filters are not copied. Such copying is used during filtering steps "modeling" stage. A further init() function call is required.

Parameters

s	Source filter bank.

getFilter()

template<typename fptype>

const fptype * avir::CDSPFracFilterBankLin< fptype >::getFilter

(

const int

i

)

Returns the pointer to the specified interpolation table filter.

The filter will be created if it is not yet created.

Parameters

i	Filter (fractional delay) index, in the range 0 to ReqFracCount - 1, inclusive.

Returns

Pointer to filter. Higher order polynomial coefficients are stored after previous order coefficients, separated by FilterLen elements.

getFilterConst()

template<typename fptype>

const fptype * avir::CDSPFracFilterBankLin< fptype >::getFilterConst

(

const int

i

)

const

Returns the pointer to the specified interpolation table filter.

This function can be only used if the createAllFilters() function was called.

Parameters

i	Filter (fractional delay) index, in the range 0 to ReqFracCount - 1, inclusive.

Returns

Pointer to filter. Higher order polynomial coefficients are stored after previous order coefficients, separated by FilterLen elements.

init()

template<typename fptype>

void avir::CDSPFracFilterBankLin< fptype >::init	(	const int	ReqFracCount,
		const int	ReqOrder,
		const double	BaseLen,
		const double	Cutoff,
		const double	aWFAlpha,
		const CFltBuffer &	aExtFilter,
		const int	aAlignment = 0,
		const int	FltLenAlign = 1 )

Initializes (builds) the filter bank based on the supplied parameters.

If the supplied parameters are equal to previously defined parameters, function does nothing (alignment is assumed to be never changing between the init() function calls).

Parameters

ReqFracCount	Required number of fractional delays in the filter bank. The minimal value is 2.
ReqOrder	Required order of the interpolation polynomial (0 or 1).
BaseLen	Low-pass filter's base length, in samples (taps). Affects the actual length of the filter and its overall steepness.
Cutoff	Low-pass filter's normalized cutoff frequency, [0; 1].
aWFAlpha	Peaked Cosine window function's Alpha parameter.
aExtFilter	External filter to apply to each fractional delay filter.
aAlignment	Memory alignment of the filter bank, power-of-2 value. 0 - use default stdlib alignment.
FltLenAlign	Filter's length alignment, power-of-2 value.

operator==()

template<typename fptype>

bool avir::CDSPFracFilterBankLin< fptype >::operator==

(

const CDSPFracFilterBankLin< fptype > &

s

)

const

Compares this filter bank and another filter bank, and returns true, if their parameters are equal. Alignment is not taken into account.

Parameters

s	Filter bank to compare to.

Returns

true, if compared banks have equal parameters.