avir::CDSPFracFilterBankLin< fptype > Class Template Reference

#include <avir.h>

Public Member Functions
int	calcInitComplexity (const CBuffer< uint8_t > &FracUseMap) const
void	copyInitParams (const CDSPFracFilterBankLin &s)
void	createAllFilters ()
const fptype *	getFilter (const int i)
int	getFilterLen () const
int	getFracCount () const
int	getOrder () const
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)
bool	operator== (const CDSPFracFilterBankLin &s) const

Detailed Description

template<class 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

template<class fptype>

int avir::CDSPFracFilterBankLin< fptype >::calcInitComplexity

(

const CBuffer< uint8_t > &

FracUseMap

)

const

Function 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.

template<class fptype>

void avir::CDSPFracFilterBankLin< fptype >::copyInitParams

(

const CDSPFracFilterBankLin< fptype > &

s

)

Copy constructor 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.

template<class fptype>

void avir::CDSPFracFilterBankLin< fptype >::createAllFilters

(

)

Function makes sure all fractional delay filters were created.

template<class fptype>

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

(

const int

i

)

Function returns the pointer to the specified interpolation table filter.

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 after previous order coefficients, separated by FilterLen elements.

template<class fptype>

int avir::CDSPFracFilterBankLin< fptype >::getFilterLen

(

)

const

Returns

The length of each fractional delay filter, in samples (taps). Always an even value.

template<class fptype>

int avir::CDSPFracFilterBankLin< fptype >::getFracCount

(

)

const

Returns

The number of fractional filters in use by *this bank.

template<class fptype>

int avir::CDSPFracFilterBankLin< fptype >::getOrder

(

)

const

Returns

The order of the interpolation polynomial.

template<class 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
	)

Function 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.

template<class fptype>

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

(

const CDSPFracFilterBankLin< fptype > &

s

)

const

Operator 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.