Dirac - A Video Codec

Created by the British Broadcasting Corporation.


dirac::SequenceCompressor Class Reference

Compresses a sequence of frames from a stream. More...

#include <seq_compress.h>

Collaboration diagram for dirac::SequenceCompressor:

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List of all members.

Public Member Functions

Private Member Functions

Private Attributes


Detailed Description

This class compresses a sequence of frames, frame by frame. It currently uses GOP parameters set in the encoder parameters in order to define the temporal prediction structure. A version to incorporate non-GOP structures is TBC.


Constructor & Destructor Documentation

dirac::SequenceCompressor::SequenceCompressor StreamPicInput pin,
std::ostream *  outfile,
EncoderParams encp
 

Creates a sequence compressor, and prepares to begin compressing with the first frame.Sets up frame padding in the picture input if necesary

Parameters:
pin an input stream containing a sequence of frames
outfile an output stream for the compressed output
encp parameters for the encoding process

dirac::SequenceCompressor::~SequenceCompressor  ) 
 

Destructor. Must delete IO objects created by constructor.

dirac::SequenceCompressor::SequenceCompressor const SequenceCompressor cpy  )  [private]
 

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


Member Function Documentation

int dirac::SequenceCompressor::CodedToDisplay const int  fnum  )  [private]
 

Uses the GOP parameters to convert frame numbers in coded order to display order

Parameters:
fnum the frame number in coded order

Frame& dirac::SequenceCompressor::CompressNextFrame  ) 
 

This function codes the next frame in coding order and returns the next frame 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 frame 0. At the end you will need to loop for longer to get all the frames out. It's up to the calling function to do something with the decoded frames as they come out -- write them to screen or to file, for example. . If coding is fast enough the compressed version could be watched real-time (with suitable buffering in the calling function to account for encode-time variations).

NOTE: LoadNextFrame must be called atleast once before invoking this method.

Returns:
reference to the next locally decoded frame available for display

void dirac::SequenceCompressor::EndSequence  ) 
 

bool dirac::SequenceCompressor::Finished  )  [inline]
 

Indicates whether or not the last frame in the sequence has been compressed.

Returns:
true if last frame has been compressed; false if not

const Frame* dirac::SequenceCompressor::GetFrameEncoded  ) 
 

const MEData* dirac::SequenceCompressor::GetMEData  ) 
 

bool dirac::SequenceCompressor::LoadNextFrame  ) 
 

Load one frame of data into the Sequence Compressor. Sets m_all_done to true if no more data is available to be loaded.

Returns:
true - if frame load succeeded. false - otherwise

void dirac::SequenceCompressor::MakeFrameReport  )  [private]
 

void dirac::SequenceCompressor::MakeSequenceReport  )  [private]
 

SequenceCompressor& dirac::SequenceCompressor::operator= const SequenceCompressor rhs  )  [private]
 

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

void dirac::SequenceCompressor::WriteStreamHeader  )  [private]
 

This contains all the block information used for motion compensation. However, temporal prediction structures are defined via the frame headers, and so a simple GOP need not be used or, if so, can be altered on the fly.


Member Data Documentation

bool dirac::SequenceCompressor::m_all_done [private]
 

int dirac::SequenceCompressor::m_current_code_fnum [private]
 

int dirac::SequenceCompressor::m_current_display_fnum [private]
 

int dirac::SequenceCompressor::m_delay [private]
 

EncoderParams& dirac::SequenceCompressor::m_encparams [private]
 

FrameBuffer* dirac::SequenceCompressor::m_fbuffer [private]
 

FrameCompressor dirac::SequenceCompressor::m_fcoder [private]
 

bool dirac::SequenceCompressor::m_just_finished [private]
 

Flag which is false if we've been all-done for more than one frame, true otherwise (so that we can take actions on finishing once only).

int dirac::SequenceCompressor::m_last_frame_read [private]
 

FrameBuffer* dirac::SequenceCompressor::m_origbuffer [private]
 

StreamPicInput* dirac::SequenceCompressor::m_pic_in [private]
 

QualityMonitor dirac::SequenceCompressor::m_qmonitor [private]
 

int dirac::SequenceCompressor::m_show_fnum [private]
 


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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