ResamplePolyphaseGetFixedFilter

Gets polyphase resampling filter coefficients.

Syntax

IppStatus ippsResamplePolyphaseGetFixedFilter_16s(Ipp16s* pDst, int step, int height, const IppsResamplingPolyphaseFixed_16s* pSpec);

IppStatus ippsResamplePolyphaseGetFixedFilter_32f(Ipp32f* pDst, int step, int height, const IppsResamplingPolyphaseFixed_32f* pSpec);

Include Files

ipps.h

Domain Dependencies

Headers: ippcore.h, ippvm.h

Libraries: ippcore.lib, ippvm.lib

Parameters

pDst	The pointer to the output vector of filter coefficients.
step	The row step in pDst vector.
height	The number of filters (the number of rows in pDst vector).
pSpec	The pointer to the resampling state structure.

Description

This function exports filter coefficients from the polyphase resampling structure. If the step value is less than the filter length, only first step coefficients are exported.

Return Values

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error when one of the specified pointers is NULL.
ippStsSizeErr	Indicates an error when step or height is less than or equal to 0.
ippStsBadArgErr	Indicates an error when height is greater than the number of filters in pSpec structure.

Example

The code example below demonstrates export and import of the Polyphase Resampling Filter Bank.

int inRate=16000; // input frequency
 int outRate=8000; // output frequency
 int history; // half of filter length
 char fname[]="filter.flt\0";
 // coefficient file name
 {
 int size,len,height;
 FILE *file; short *pFilter;
 IppsresamplingPolyphaseFixed_16s *state;
 history=(int)(64.0f*0.5*IPP_MAX(1.0,1.0/(double)outRate/(double)inRate))+1;
 ippsResamplePolyphaseFixedGetSize_16s(inRate, outRate, 2*(history-1), &size, &len, &height, ippAlgHintFast);
 state = (IppsResamlingPolyphaseFixed_16s*)ippsMalloc_8u(size);
 ippsResamplePolyphaseFixedInit_16s(inRate,outRate,2*(history-1), 0.95f, 9.0f, state, ippAlgHintFast);
 pFilter=ippsMalloc_16s(len*height); ippsResamplePolyphaseGetFixedFilter_16s(pFilter,len,height,state);
 file=fopen(fname,"wb"); fwrite(&size,sizeof(int),1,file);
 fwrite(&len,sizeof(int),1,file);
 fwrite(&height,sizeof(int),1,file);
 fwrite(pFilter,sizeof(short),len*height,file);
 fclose(file); ippsFree(pFilter);
 ippsFree (state);
 }
 {
 int size,len,height; FILE *file;
 short *pFilter;
 IppsresamplingPolyphaseFixed_16s *state;
 history=(int)(64.0f*0.5*IPP_MAX(1.0,1.0/(double)outRate/(double)inRate))+1;
 file=fopen(fname,"rb");
 fread(&size,sizeof(int),1,file);
 fread(&len,sizeof(int),1,file);
 fread(&height,sizeof(int),1,file);
 pFilter=ippsMalloc_16s(len*height);
 fread(pFilter,sizeof(short),len*height,file);
 fclose(file);
 state=(IppsresamplingPolyphaseFixed_16s*)ippsMalloc_8u(size);
 ippsResamplePolyphaseFixedInit_16s(inRate,outRate,2*(history-1), 0.95f, 9.0f, state, ippAlgHintFast);
 ippsResamplePolyphaseSetFixedFilter_16s((const Ipp16s*)pFilter,len,height, (IppsresamplingPolyphaseFixed_16s*)state);
 ippsFree(pFilter);
 // use of polyphase filter
 … 
 ippsFree(state); 
}