avir::CLancIR::CResizeFilters Class Reference

Class for fractional delay filter bank storage and calculation. More...

#include <lancir.h>

Classes
class	CSineGen
	Sine-wave signal generator class. More...

Public Member Functions
const float *	getFilter (const double x)
	Filter acquisition function.
bool	update (const double la0, const double k0, const int ElCount0)
	Function updates the filter bank.

Public Attributes
int	KernelLen
	Resampling filter kernel's length, taps. Available after the update() function call. Always an even value, should not be lesser than 4.

Protected Member Functions
void	makeFilterNorm (float *op, const double FracDelay) const
	Filter calculation function.
void	setBuf (const int bi)
	Current buffer (filter batch) repositioning function.

Static Protected Member Functions
static void	replicateFilter (float *const p, const int kl, const int erp)
	Filter tap replication function, for SIMD operations.

Protected Attributes
float *	Bufs [BufCount]
	Address-aligned Bufs0.
float *	Bufs0 [BufCount]
	Buffers that hold all filters, original.
int	Bufs0Len [BufCount]
	Allocated lengthes in Bufs0, in float elements.
int	CurBuf
	Filter buffer currently being filled.
int	CurBufFill
	The number of fractional positions filled in the current filter buffer.
int	ElCount
	Current ElCount.
int	ElRepl
	The number of repetitions of each filter tap.
float **	Filters
	Fractional delay filters for all positions. A particular pointer equals NULL if a filter for such position has not been created yet.
int	FiltersLen
	Allocated length of Filters, in elements.
int	fl2
	Half resampling filter's length, integer.
int	FracCount
	The number of fractional positions for which filters can be created.
double	Freq
	Circular frequency of the filter.
double	FreqA
	Circular frequency of the window function.
double	k
	Current k.
int	KernelLenA
	SIMD-aligned and replicated filter kernel's length.
double	la
	Current la.
double	Len2
	Half resampling filter's length, unrounded.

Static Protected Attributes
static const int	BufCount = 4
	The maximal number of buffers (filter batches) that can be in use.
static const int	BufLen = 256
	The number of fractional filters a single buffer (filter batch) may contain. Both the BufLen and BufCount should correspond to the FracCount used.

Friends
class	CResizeScanline

Detailed Description

Class for fractional delay filter bank storage and calculation.

Member Function Documentation

getFilter()

const float * avir::CLancIR::CResizeFilters::getFilter

(

const double

x

)

Filter acquisition function.

Function returns filter at the specified fractional offset. This function can only be called after a prior update() function call.

Parameters

x	Fractional offset, [0; 1].

Returns

Pointer to a previously-calculated or a new filter.

makeFilterNorm()

void avir::CLancIR::CResizeFilters::makeFilterNorm ( float * op, const double FracDelay ) const

protected

Filter calculation function.

Function creates a filter for the specified fractional delay. The update() function should be called prior to calling this function. The created filter is normalized (DC gain=1).

Parameters

[out]	op	Output filter buffer.
	FracDelay	Fractional delay, 0 to 1, inclusive.

replicateFilter()

static void avir::CLancIR::CResizeFilters::replicateFilter ( float *const p, const int kl, const int erp )

staticprotected

Filter tap replication function, for SIMD operations.

Function replicates taps of the specified filter so that it can be used with SIMD loading instructions. This function works "in-place".

Parameters

[in,out]	p	Filter buffer pointer, should be sized to contain kl * erp elements.
	kl	Filter kernel's length, in taps.
	erp	The number of repetitions to apply.

setBuf()

void avir::CLancIR::CResizeFilters::setBuf ( const int bi )

protected

Current buffer (filter batch) repositioning function.

Function changes the buffer currently being filled, checks its size and reallocates it, if necessary, then resets its fill counter.

Parameters

bi	A new current buffer index.

update()

bool avir::CLancIR::CResizeFilters::update	(	const double	la0,
		const double	k0,
		const int	ElCount0 )

Function updates the filter bank.

Parameters

la0	Lanczos a parameter value (greater or equal to 2.0), can be fractional.
k0	Resizing step.
ElCount0	Image's element count, may be used for SIMD filter tap replication.

Returns

true if an update occured and scanline resizing positions should be updated unconditionally.