Dirac - A Video Codec

Created by the British Broadcasting Corporation.

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dirac::WaveletTransform Class Reference

A class to do wavelet transforms. More...

#include <wavelet_utils.h>

List of all members.

Public Member Functions

• WaveletTransform (int d=4, WltFilter f=DAUB97)

  Constructor.
  

• virtual ~WaveletTransform ()

  Destructor.
  

• void Transform (const Direction d, PicArray &pic_data)

  Transforms the data to and from the wavelet domain.
  

• SubbandList & BandList ()

  Returns the set of subbands.
  

• const SubbandList & BandList () const

  Returns the set of subbands.
  

• void SetBandWeights (const float cpd, const FrameSort &fsort, const ChromaFormat &cformat, const CompSort csort)

  Sets the subband weights.
  

• ValueType GetMeanDCVal () const

  Return the expected DC band value assuming a mid-grey picture (mean val=512).
  

Private Member Functions

• WaveletTransform (const WaveletTransform &cpy)

  Private, bodyless copy constructor: class should not be copied.
  

• WaveletTransform & operator= (const WaveletTransform &rhs)

  Private, bodyless copy operator=: class should not be assigned.
  

• float PerceptualWeight (float xf, float yf, CompSort cs)

  Given x and y spatial frequencies in cycles per degree, returns a weighting value.
  

Private Attributes

• SubbandList m_band_list
• int m_depth

  Depth of the transform.
  

• WltFilter m_filt_sort

  The filter set to be used.
  

• VHFilter * m_vhfilter

  A class to do the filtering required.
  

Classes

• class PredictStep97

  Class to do two-tap prediction lifting step for Daubechies (9,7). More...
  

• class PredictStepFourTap

  Class to do symmetric four-tap prediction lifting step. More...
  

• class PredictStepShift

  Class to do two-tap prediction lifting step. More...
  

• class UpdateStep97

  Class to do two-tap update lifting step for Daubechies (9,7). More...
  

• class UpdateStepFourTap

  Class to do symmetric four-tap update lifting step. More...
  

• class UpdateStepShift

  Class to do two-tap updating lifting step. More...
  

• class VHFilter

  A virtual parent class to do vertical and horizontal splitting with wavelet filters. More...
  

• class VHFilter13_5

  An extension of Approx9_7, with a better low-pass filter but more computation. More...
  

• class VHFilter5_3

  Class to do (5,3) wavelet filtering operations. More...
  

• class VHFilterApprox9_7

  Class to do an approximation to Daubechies (9,7) but with just two lifting steps. More...
  

• class VHFilterDaub9_7

  Class to do Daubechies (9,7) filtering operations. More...
  

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Detailed Description

A class to do forward and backward wavelet transforms by iteratively splitting or merging the lowest frequency band.

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Constructor & Destructor Documentation

dirac::WaveletTransform::WaveletTransform	(	int	d = 4,
		WltFilter	f = DAUB97
	)

virtual dirac::WaveletTransform::~WaveletTransform

(

)

[virtual]

dirac::WaveletTransform::WaveletTransform

(

const WaveletTransform &

cpy

)

[private]

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Member Function Documentation

const SubbandList& dirac::WaveletTransform::BandList

(

)

const [inline]

SubbandList& dirac::WaveletTransform::BandList

(

)

[inline]

ValueType dirac::WaveletTransform::GetMeanDCVal

(

)

const

WaveletTransform& dirac::WaveletTransform::operator=

(

const WaveletTransform &

rhs

)

[private]

float dirac::WaveletTransform::PerceptualWeight	(	float	xf,
		float	yf,
		CompSort	cs
	)			[private]

void dirac::WaveletTransform::SetBandWeights	(	const float	cpd,
		const FrameSort &	fsort,
		const ChromaFormat &	cformat,
		const CompSort	csort
	)

Sets perceptual weights for the subbands. Takes into account both perceptual factors (weight noise less at higher spatial frequencies) and the scaling needed for the wavelet transform.

Parameters:

	cpd	perctual factor - the number of cycles per degree
	fsort	the frame sort (I, L1 or L2)
	cformat	the chroma format
	csort	the component type (Y, U or V)

void dirac::WaveletTransform::Transform	(	const Direction	d,
		PicArray &	pic_data
	)

Transforms the data to and from the wavelet domain.

Parameters:

	d	the direction of the transform
	pic_data	the data to be transformed

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Member Data Documentation

SubbandList dirac::WaveletTransform::m_band_list [private]

int dirac::WaveletTransform::m_depth [private]

WltFilter dirac::WaveletTransform::m_filt_sort [private]

VHFilter* dirac::WaveletTransform::m_vhfilter [private]

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

• wavelet_utils.h

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© 2004 British Broadcasting Corporation. Dirac code licensed under the Mozilla Public License (MPL) Version 1.1.
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