Dirac - A Video Codec

Created by the British Broadcasting Corporation.


dirac::SequenceDecompressor Class Reference

Decompresses a sequence of pictures from a stream. More...

#include <seq_decompress.h>

Collaboration diagram for dirac::SequenceDecompressor:

Public Member Functions

 SequenceDecompressor (ParseUnitByteIO &parseunit, bool verbosity)
 Constructor.
 ~SequenceDecompressor ()
 Destructor.
void NewAccessUnit (ParseUnitByteIO &parseunit_byteio)
 Marks beginning of a new AccessUnit.
const PictureDecompressNextPicture (ParseUnitByteIO *p_parseunit_byteio)
 Decompress the next picture in sequence.
const PictureGetNextPicture ()
 Get the next picture available for display.
const PictureParamsGetNextPictureParams () const
 Get the next picture parameters.
bool Finished ()
 Determine if decompression is complete.
ParseParamsGetParseParams ()
 Interrogates for parse parameters.
SourceParamsGetSourceParams ()
 Interrogates for source parameters.
DecoderParamsGetDecoderParams ()
 Interrogates for coding parameters.

Private Member Functions

 SequenceDecompressor (const SequenceDecompressor &cpy)
 Copy constructor is private and body-less.
SequenceDecompressoroperator= (const SequenceDecompressor &rhs)
 Assignment = is private and body-less.

Private Attributes

bool m_all_done
 Completion flag, returned via the Finished method.
DecoderParams m_decparams
 Parameters for the decompression, as provided in constructor.
ParseParams m_parse_params
 The parse parameters obtained from the stream header.
SourceParams m_srcparams
 The source parameters obtained from the stream header.
PictureBufferm_pbuffer
 A picture buffer used for local storage of pictures whilst pending re-ordering or being used for reference.
int m_current_code_pnum
 Number of the picture in coded order which is to be decoded.
int m_delay
 A delay so that we don't display what we haven't decoded.
int m_last_picture_read
 Index, in display order, of the last picture read.
int m_show_pnum
 Index, in display order of the picture to be displayed next - computed from delay and current_code_pnum.
PictureDecompressorm_pdecoder
 Picture decompressor object.
int m_highest_pnum
 Highest picture-num processed - for tracking end-of-sequence.

Detailed Description

This class decompresses a sequence of frames, picture by picture.

Constructor & Destructor Documentation

◆ SequenceDecompressor() [1/2]

dirac::SequenceDecompressor::SequenceDecompressor ( ParseUnitByteIO & parseunit,
bool verbosity )

Initializes the decompressor with an input stream and level of output detail.

Parameters
parseunitFirst access-unit of new sequence
verbositywhen true, increases the amount of information displayed during decompression

Referenced by operator=(), and SequenceDecompressor().

◆ ~SequenceDecompressor()

dirac::SequenceDecompressor::~SequenceDecompressor ( )

Closes files and releases resources.

◆ SequenceDecompressor() [2/2]

dirac::SequenceDecompressor::SequenceDecompressor ( const SequenceDecompressor & cpy)
private

Copy constructor is private and body-less. This class should not be copied.

References SequenceDecompressor().

Member Function Documentation

◆ DecompressNextPicture()

const Picture * dirac::SequenceDecompressor::DecompressNextPicture ( ParseUnitByteIO * p_parseunit_byteio)

This function decodes the next picture in coding order and returns the next picture in display order. In general these will differ, and because of re-ordering there is a delay which needs to be imposed. This creates problems at the start and at the end of the sequence which must be dealt with. At the start we just keep outputting picture 0. At the end you will need to loop for longer to get all the pictures out. It's up to the calling function to do something with the decoded pictures as they come out – write them to screen or to file, as required.

Parameters
p_parseunit_byteioPicture information in Dirac-stream format
Returns
reference to the next locally decoded picture available for display

◆ Finished()

bool dirac::SequenceDecompressor::Finished ( )

Indicates whether or not the last picture in the sequence has been decompressed.

Returns
true if last picture has been compressed; false if not

◆ GetDecoderParams()

DecoderParams & dirac::SequenceDecompressor::GetDecoderParams ( )
inline

Returns the decoder parameters used for this decompression run.

Returns
decoder parameters.

References m_decparams.

◆ GetNextPicture()

const Picture * dirac::SequenceDecompressor::GetNextPicture ( )

◆ GetNextPictureParams()

const PictureParams * dirac::SequenceDecompressor::GetNextPictureParams ( ) const

◆ GetParseParams()

ParseParams & dirac::SequenceDecompressor::GetParseParams ( )
inline

Returns the parse parameters used for this decompression run.

Returns
parse parameters.

References m_parse_params.

◆ GetSourceParams()

SourceParams & dirac::SequenceDecompressor::GetSourceParams ( )
inline

Returns the source parameters used for this decompression run.

Returns
source parameters.

References m_srcparams.

◆ NewAccessUnit()

void dirac::SequenceDecompressor::NewAccessUnit ( ParseUnitByteIO & parseunit_byteio)
Parameters
parseunit_byteioAccessUnit info in Dirac-stream format

◆ operator=()

SequenceDecompressor & dirac::SequenceDecompressor::operator= ( const SequenceDecompressor & rhs)
private

Assignment = is private and body-less. This class should not be assigned.

References SequenceDecompressor().

Member Data Documentation

◆ m_all_done

bool dirac::SequenceDecompressor::m_all_done
private

◆ m_current_code_pnum

int dirac::SequenceDecompressor::m_current_code_pnum
private

◆ m_decparams

DecoderParams dirac::SequenceDecompressor::m_decparams
private

Referenced by GetDecoderParams().

◆ m_delay

int dirac::SequenceDecompressor::m_delay
private

◆ m_highest_pnum

int dirac::SequenceDecompressor::m_highest_pnum
private

◆ m_last_picture_read

int dirac::SequenceDecompressor::m_last_picture_read
private

◆ m_parse_params

ParseParams dirac::SequenceDecompressor::m_parse_params
private

Referenced by GetParseParams().

◆ m_pbuffer

PictureBuffer* dirac::SequenceDecompressor::m_pbuffer
private

◆ m_pdecoder

PictureDecompressor* dirac::SequenceDecompressor::m_pdecoder
private

◆ m_show_pnum

int dirac::SequenceDecompressor::m_show_pnum
private

◆ m_srcparams

SourceParams dirac::SequenceDecompressor::m_srcparams
private

Referenced by GetSourceParams().


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

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