SoDa::ReSampler Class Reference

Rational Resampler. More...

#include <ReSampler.hxx>

Public Member Functions
	ReSampler (unsigned int interp_ratio, unsigned int decim_ratio, unsigned int _inlen, unsigned int filter_len)
	Constructor. More...
unsigned int	apply (std::complex< float > *in, std::complex< float > *out, float gain=1.0)
	apply the resampler to a buffer of IQ samples. More...
unsigned int	apply (float *in, float *out, float gain=1.0)
	apply the resampler to a buffer of scalar samples. More...

Private Member Functions
void	CreateFilter (unsigned int filter_len)
	create a filter bank for a polyphase resampler. More...

Private Attributes
int	filter_len
	the length of the polyphase filter that we're using. More...
unsigned int	iM
unsigned int	dN
unsigned int	Q
unsigned int	tail_index
unsigned int	inlen
unsigned int	M
unsigned int	N
std::complex< float > **	c_filt
	filter bank for interp/deci filter More...
std::complex< float > *	filt_fft
	the filtered image of the input stream More...
std::complex< float > *	interp_res
	the interpolation result More...
std::complex< float > *	in_fft
	the result of the first fft stage More...
std::complex< float > *	inbuf
	the fft input buffer More...
float	transform_gain
float	gain_correction
fftwf_plan	in_fft_plan
fftwf_plan	mid_ifft_plan

Detailed Description

Rational Resampler.

Create a resampler that upsamples by an interpolation rate and downsamples by a decimation rate.

Definition at line 41 of file ReSampler.hxx.

Constructor & Destructor Documentation

ReSampler()

SoDa::ReSampler::ReSampler	(	unsigned int	interp_ratio,
		unsigned int	decim_ratio,
		unsigned int	_inlen,
		unsigned int	filter_len
	)

Constructor.

Parameters

interp_ratio	upsample rate
decim_ratio	downsample rate
_inlen	the input buffer length (output buffer will be _inlin * interp_ratio / decimation_ratio)
filter_len	the minimum length of the antialiasing filter

Definition at line 82 of file ReSampler.cxx.

References c_filt, CreateFilter(), dN, filt_fft, filter_len, iM, in_fft, in_fft_plan, inbuf, inlen, interp_res, ipow(), M, mid_ifft_plan, N, Q, tail_index, and transform_gain.

Member Function Documentation

apply() [1/2]

unsigned int SoDa::ReSampler::apply	(	std::complex< float > *	in,
		std::complex< float > *	out,
		float	gain = 1.0
	)

apply the resampler to a buffer of IQ samples.

Parameters

in	input buffer
out	output buffer
gain	– multiply output by gain

Definition at line 272 of file ReSampler.cxx.

References c_filt, dN, filt_fft, iM, in_fft, in_fft_plan, inbuf, interp_res, M, mid_ifft_plan, N, Q, tail_index, and transform_gain.

Referenced by SoDa::ReSample48to625::apply(), SoDa::ReSample625to48::apply(), and main().

apply() [2/2]

unsigned int SoDa::ReSampler::apply	(	float *	in,
		float *	out,
		float	gain = 1.0
	)

apply the resampler to a buffer of scalar samples.

Parameters

in	input buffer
out	output buffer
gain	– multiply output by gain

Definition at line 322 of file ReSampler.cxx.

References c_filt, dN, filt_fft, iM, in_fft, in_fft_plan, inbuf, interp_res, M, mid_ifft_plan, N, Q, tail_index, and transform_gain.

CreateFilter()

void SoDa::ReSampler::CreateFilter ( unsigned int  filter_len )

private

create a filter bank for a polyphase resampler.

(Though we do it in the frequency domain.)

Parameters

filter_len

the minimum length of the anti-alias filter

Definition at line 171 of file ReSampler.cxx.

References c_filt, dN, filter_len, iM, and N.

Referenced by ReSampler().

Member Data Documentation

c_filt

std::complex<float>** SoDa::ReSampler::c_filt

private

filter bank for interp/deci filter

Definition at line 87 of file ReSampler.hxx.

Referenced by apply(), CreateFilter(), and ReSampler().

dN

unsigned int SoDa::ReSampler::dN

private

Definition at line 85 of file ReSampler.hxx.

Referenced by apply(), CreateFilter(), and ReSampler().

filt_fft

std::complex<float>* SoDa::ReSampler::filt_fft

private

the filtered image of the input stream

Definition at line 88 of file ReSampler.hxx.

Referenced by apply(), and ReSampler().

filter_len

int SoDa::ReSampler::filter_len

private

the length of the polyphase filter that we're using.

Definition at line 83 of file ReSampler.hxx.

Referenced by CreateFilter(), and ReSampler().

gain_correction

float SoDa::ReSampler::gain_correction

private

Definition at line 95 of file ReSampler.hxx.

iM

unsigned int SoDa::ReSampler::iM

private

Definition at line 85 of file ReSampler.hxx.

Referenced by apply(), CreateFilter(), and ReSampler().

in_fft

std::complex<float>* SoDa::ReSampler::in_fft

private

the result of the first fft stage

Definition at line 90 of file ReSampler.hxx.

Referenced by apply(), and ReSampler().

in_fft_plan

fftwf_plan SoDa::ReSampler::in_fft_plan

private

Definition at line 98 of file ReSampler.hxx.

Referenced by apply(), and ReSampler().

inbuf

std::complex<float>* SoDa::ReSampler::inbuf

private

the fft input buffer

Definition at line 91 of file ReSampler.hxx.

Referenced by apply(), and ReSampler().

inlen

unsigned int SoDa::ReSampler::inlen

private

Definition at line 86 of file ReSampler.hxx.

Referenced by ReSampler().

interp_res

std::complex<float>* SoDa::ReSampler::interp_res

private

the interpolation result

Definition at line 89 of file ReSampler.hxx.

Referenced by apply(), and ReSampler().

M

unsigned int SoDa::ReSampler::M

private

Definition at line 86 of file ReSampler.hxx.

Referenced by apply(), and ReSampler().

mid_ifft_plan

fftwf_plan SoDa::ReSampler::mid_ifft_plan

private

Definition at line 99 of file ReSampler.hxx.

Referenced by apply(), and ReSampler().

N

unsigned int SoDa::ReSampler::N

private

Definition at line 86 of file ReSampler.hxx.

Referenced by apply(), CreateFilter(), and ReSampler().

Q

unsigned int SoDa::ReSampler::Q

private

Definition at line 85 of file ReSampler.hxx.

Referenced by apply(), and ReSampler().

tail_index

unsigned int SoDa::ReSampler::tail_index

private

Definition at line 85 of file ReSampler.hxx.

Referenced by apply(), and ReSampler().

transform_gain

float SoDa::ReSampler::transform_gain

private

Definition at line 94 of file ReSampler.hxx.

Referenced by apply(), and ReSampler().

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The documentation for this class was generated from the following files:

• src/ReSampler.hxx
• src/ReSampler.cxx