staffpad::audio::FourierTransform Class Reference

#include <FourierTransform_pffft.h>

Public Member Functions
	FourierTransform (int32_t newBlockSize)
	~FourierTransform ()
int	getSize () const
void	forwardReal (const SamplesReal &t, SamplesComplex &c)
void	inverseReal (const SamplesComplex &c, SamplesReal &t)

Private Attributes
PFFFT_Setup *	realFftSpec = nullptr
PFFFT_Setup *	complexFftSpec = nullptr
float *	_pffft_scratch = nullptr
const int32_t	_blockSize
int32_t	_order = 0

Detailed Description

Definition at line 14 of file FourierTransform_pffft.h.

Constructor & Destructor Documentation

FourierTransform()

staffpad::audio::FourierTransform::FourierTransform

(

int32_t

newBlockSize

)

Definition at line 7 of file FourierTransform_pffft.cpp.

    : _blockSize { newBlockSize }
{
  _pffft_scratch = (float*)pffft_aligned_malloc(_blockSize * sizeof(float));
  realFftSpec = pffft_new_setup(_blockSize, PFFFT_REAL);
}

References _blockSize, _pffft_scratch, and realFftSpec.

~FourierTransform()

staffpad::audio::FourierTransform::~FourierTransform

(

)

Definition at line 14 of file FourierTransform_pffft.cpp.

{
  if (_pffft_scratch)
  {
    pffft_aligned_free(_pffft_scratch);
    _pffft_scratch = nullptr;
  }
  if (realFftSpec)
  {
    pffft_destroy_setup(realFftSpec);
    realFftSpec = nullptr;
  }
}

References _pffft_scratch, and realFftSpec.

Member Function Documentation

forwardReal()

void staffpad::audio::FourierTransform::forwardReal	(	const SamplesReal &	t,
		SamplesComplex &	c
	)

Definition at line 28 of file FourierTransform_pffft.cpp.

{
  assert(t.getNumSamples() == _blockSize);
 
  for (auto ch = 0; ch < t.getNumChannels(); ++ch)
  {
    auto* spec = c.getPtr(ch); // interleaved complex numbers, size _blockSize + 2
    auto* cpx_flt = (float*)spec;
    pffft_transform_ordered(realFftSpec, t.getPtr(ch), cpx_flt, _pffft_scratch, PFFFT_FORWARD);
    // pffft combines dc and nyq values into the first complex value,
    // adjust to CCS format.
    auto dc = cpx_flt[0];
    auto nyq = cpx_flt[1];
    spec[0] = {dc, 0.f};
    spec[c.getNumSamples() - 1] = {nyq, 0.f};
  }
}

References _blockSize, _pffft_scratch, staffpad::SamplesFloat< T >::getNumChannels(), staffpad::SamplesFloat< T >::getNumSamples(), staffpad::SamplesFloat< T >::getPtr(), and realFftSpec.

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getSize()

int staffpad::audio::FourierTransform::getSize ( ) const

inline

Definition at line 20 of file FourierTransform_pffft.h.

{ return static_cast<int>(_blockSize); }

References _blockSize.

inverseReal()

void staffpad::audio::FourierTransform::inverseReal	(	const SamplesComplex &	c,
		SamplesReal &	t
	)

Definition at line 46 of file FourierTransform_pffft.cpp.

{
  assert(c.getNumSamples() == _blockSize / 2 + 1);
 
  for (auto ch = 0; ch < c.getNumChannels(); ++ch)
  {
    auto* spec = c.getPtr(ch);
    // Use t to convert in-place from CCS to pffft format
    t.assignSamples(ch, (float*)spec);
    auto* ts = t.getPtr(ch);
    ts[0] = spec[0].real();
    ts[1] = spec[c.getNumSamples() - 1].real();
    pffft_transform_ordered(realFftSpec, ts, ts, _pffft_scratch, PFFFT_BACKWARD);
  }
}

References _blockSize, _pffft_scratch, staffpad::SamplesFloat< T >::assignSamples(), staffpad::SamplesFloat< T >::getNumChannels(), staffpad::SamplesFloat< T >::getNumSamples(), staffpad::SamplesFloat< T >::getPtr(), and realFftSpec.

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Member Data Documentation

_blockSize

const int32_t staffpad::audio::FourierTransform::_blockSize

private

Definition at line 30 of file FourierTransform_pffft.h.

Referenced by forwardReal(), FourierTransform(), getSize(), and inverseReal().

_order

int32_t staffpad::audio::FourierTransform::_order = 0

private

Definition at line 31 of file FourierTransform_pffft.h.

_pffft_scratch

float* staffpad::audio::FourierTransform::_pffft_scratch = nullptr

private

Definition at line 28 of file FourierTransform_pffft.h.

Referenced by forwardReal(), FourierTransform(), inverseReal(), and ~FourierTransform().

complexFftSpec

PFFFT_Setup* staffpad::audio::FourierTransform::complexFftSpec = nullptr

private

Definition at line 27 of file FourierTransform_pffft.h.

realFftSpec

PFFFT_Setup* staffpad::audio::FourierTransform::realFftSpec = nullptr

private

Definition at line 26 of file FourierTransform_pffft.h.

Referenced by forwardReal(), FourierTransform(), inverseReal(), and ~FourierTransform().

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

• FourierTransform_pffft.h
• FourierTransform_pffft.cpp