Dirac - A Video Codec

Created by the British Broadcasting Corporation.

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dirac::BandCodec Class Reference

A general class for coding and decoding wavelet subband data. More...

#include <band_codec.h>

Inheritance diagram for dirac::BandCodec:

List of all members.

Public Member Functions

• BandCodec (SubbandByteIO *subband_byteio, size_t number_of_contexts, const SubbandList &band_list, int band_num)

  Constructor.
  

• void InitContexts ()

  Initialise the contexts according to predefined counts.
  

Protected Member Functions

• void CodeVal (PicArray &in_data, const int xpos, const int ypos, const ValueType val)

  Code an individual quantised value and perform inverse-quantisation.
  

• void DecodeVal (PicArray &out_data, const int xpos, const int ypos)

  Decode an individual quantised value and perform inverse-quantisation.
  

• void CodeQIndexOffset (const int offset)

  Encode the offset for a code block quantiser.
  

• int DecodeQIndexOffset ()

  Decode the offset for a code block quantiser.
  

• void SetToVal (const CodeBlock &code_block, PicArray &pic_data, const ValueType val)

  Set a code block area to a given value.
  

• void ClearBlock (const CodeBlock &code_block, PicArray &pic_data)

  Set all block values to 0.
  

Protected Attributes

• int m_bnum

  variables
  

• const Subband m_node

  the subband being coded
  

• int m_vol

  size of the subband
  

• int m_reset_coeff_num

  the number of coefficients after which contexts are reset
  

• int m_coeff_count

  count of the coefficients since the last context reset
  

• int m_qf

  quantisation value
  

• ValueType m_offset

  reconstruction point
  

• ValueType m_nhood_sum

  sum of a neighbourhood of previously (de)coded values
  

• Subband m_pnode

  the parent subband
  

• int m_pxp

  coords of the parent subband
  

• int m_pyp
• int m_pxl
• int m_pyl
• int m_pxpos

  position of the parent coefficient
  

• int m_pypos
• bool m_parent_notzero

  True if the parent of a coeff is not zero.
  

Private Member Functions

• virtual void DoWorkCode (PicArray &in_data)
• virtual void DoWorkDecode (PicArray &out_data)
• virtual void CodeCoeffBlock (const CodeBlock &code_block, PicArray &in_data)
• virtual void DecodeCoeffBlock (const CodeBlock &code_block, PicArray &out_data)
• void ResetAll ()

  The method by which _all_ the counts are resized.
  

• int ChooseFollowContext (const int bin_number) const

  A function for choosing the context for "follow bits".
  

• int ChooseInfoContext () const

  A function for choosing the context for "information bits".
  

• int ChooseSignContext (const PicArray &data, const int xpos, const int ypos) const

  A function for choosing the context for sign bits.
  

• BandCodec (const BandCodec &cpy)

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

• BandCodec & operator= (const BandCodec &rhs)

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

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Detailed Description

A general class for coding and decoding wavelet subband data, deriving from the abstract ArithCodec class.

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Constructor & Destructor Documentation

dirac::BandCodec::BandCodec	(	SubbandByteIO *	subband_byteio,
		size_t	number_of_contexts,
		const SubbandList &	band_list,
		int	band_num
	)

Creates a BandCodec object to encode subband data

Parameters:

	subband_byteio	inout/output for the encoded bits
	number_of_contexts	the number of contexts used in the encoding process
	band_list	the set of all the subbands
	band_num	the number of the subband being coded

dirac::BandCodec::BandCodec

(

const BandCodec &

cpy

)

[private]

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Member Function Documentation

int dirac::BandCodec::ChooseFollowContext

(

const int

bin_number

)

const [inline, private]

int dirac::BandCodec::ChooseInfoContext

(

)

const [inline, private]

int dirac::BandCodec::ChooseSignContext	(	const PicArray &	data,
		const int	xpos,
		const int	ypos
	)			const [inline, private]

void dirac::BandCodec::ClearBlock	(	const CodeBlock &	code_block,
		PicArray &	pic_data
	)			[inline, protected]

virtual void dirac::BandCodec::CodeCoeffBlock	(	const CodeBlock &	code_block,
		PicArray &	in_data
	)			[private, virtual]

Reimplemented in dirac::LFBandCodec, and dirac::IntraDCBandCodec.

void dirac::BandCodec::CodeQIndexOffset

(

const int

offset

)

[protected]

void dirac::BandCodec::CodeVal	(	PicArray &	in_data,
		const int	xpos,
		const int	ypos,
		const ValueType	val
	)			[inline, protected]

virtual void dirac::BandCodec::DecodeCoeffBlock	(	const CodeBlock &	code_block,
		PicArray &	out_data
	)			[private, virtual]

Reimplemented in dirac::LFBandCodec, and dirac::IntraDCBandCodec.

int dirac::BandCodec::DecodeQIndexOffset

(

)

[protected]

void dirac::BandCodec::DecodeVal	(	PicArray &	out_data,
		const int	xpos,
		const int	ypos
	)			[inline, protected]

virtual void dirac::BandCodec::DoWorkCode

(

PicArray &

in_data

)

[private, virtual]

Reimplemented in dirac::LFBandCodec, and dirac::IntraDCBandCodec.

virtual void dirac::BandCodec::DoWorkDecode

(

PicArray &

out_data

)

[private, virtual]

Reimplemented in dirac::LFBandCodec, and dirac::IntraDCBandCodec.

void dirac::BandCodec::InitContexts

(

)

[virtual]

Implements dirac::ArithCodecBase.

BandCodec& dirac::BandCodec::operator=

(

const BandCodec &

rhs

)

[private]

void dirac::BandCodec::ResetAll

(

)

[private, virtual]

Implements dirac::ArithCodecBase.

void dirac::BandCodec::SetToVal	(	const CodeBlock &	code_block,
		PicArray &	pic_data,
		const ValueType	val
	)			[inline, protected]

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Member Data Documentation

int dirac::BandCodec::m_bnum [protected]

int dirac::BandCodec::m_coeff_count [protected]

ValueType dirac::BandCodec::m_nhood_sum [protected]

const Subband dirac::BandCodec::m_node [protected]

ValueType dirac::BandCodec::m_offset [protected]

bool dirac::BandCodec::m_parent_notzero [protected]

Subband dirac::BandCodec::m_pnode [protected]

int dirac::BandCodec::m_pxl [protected]

int dirac::BandCodec::m_pxp [protected]

int dirac::BandCodec::m_pxpos [protected]

int dirac::BandCodec::m_pyl [protected]

int dirac::BandCodec::m_pyp [protected]

int dirac::BandCodec::m_pypos [protected]

int dirac::BandCodec::m_qf [protected]

int dirac::BandCodec::m_reset_coeff_num [protected]

int dirac::BandCodec::m_vol [protected]

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

• band_codec.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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