jj2000.j2k.entropy.encoder

Class PostCompRateAllocator

java.lang.Object

jj2000.j2k.image.ImgDataAdapter

jj2000.j2k.entropy.encoder.PostCompRateAllocator

All Implemented Interfaces:

ImgData

Direct Known Subclasses:

EBCOTRateAllocator

public abstract class PostCompRateAllocator
extends ImgDataAdapter

This is the abstract class from which post-compression rate allocators which generate layers should inherit. The source of data is a 'CodedCBlkDataSrcEnc' which delivers entropy coded blocks with rate-distortion statistics.

The post compression rate allocator implementation should create the layers, according to a rate allocation policy, and send the packets to a CodestreamWriter. Since the rate allocator sends the packets to the bit stream then it should output the packets to the bit stream in the order imposed by the bit stream profiles.

See Also:

CodedCBlkDataSrcEnc, CodestreamWriter

Field Summary

Fields

Modifier and Type	Field and Description
(package private) CodestreamWriter	bsWriter The bit-stream writer
(package private) HeaderEncoder	headEnc The header encoder
protected int	numLayers The number of layers.
static char	OPT_PREFIX The prefix for rate allocation options: 'A'
private static String[][]	pinfo The list of parameters that is accepted for entropy coding.
protected CodedCBlkDataSrcEnc	src The source of entropy coded data
protected J2KImageWriteParamJava	wp The source of entropy coded data

Fields inherited from class jj2000.j2k.image.ImgDataAdapter

imgdatasrc, tIdx

Constructor Summary

Constructors

Constructor and Description
PostCompRateAllocator(CodedCBlkDataSrcEnc src, int nl, CodestreamWriter bw, J2KImageWriteParamJava wp) Initializes the source of entropy coded data.

Method Summary

Modifier and Type	Method and Description
static PostCompRateAllocator	createInstance(CodedCBlkDataSrcEnc src, float rate, CodestreamWriter bw, J2KImageWriteParamJava wp) Creates a PostCompRateAllocator object for the appropriate rate allocation parameters in the parameter list 'pl', having 'src' as the source of entropy coded data, 'rate' as the target bitrate and 'bw' as the bit stream writer object.
int	getNumLayers() Returns the number of layers that are actually generated.
static String[][]	getParameterInfo() Returns the parameters that are used in this class and implementing classes.
abstract void	initialize() Initializes the rate allocation points, taking into account header overhead and such.
private static LayersInfo	parseAlayers(String params, float rate) Convenience method that parses the 'Alayers' option.
abstract void	runAndWrite() Runs the rate allocation algorithm and writes the data to the bit stream.
void	setHeaderEncoder(HeaderEncoder headEnc) Keep a reference to the header encoder.

Methods inherited from class jj2000.j2k.image.ImgDataAdapter

getCompImgHeight, getCompImgWidth, getCompSubsX, getCompSubsY, getCompULX, getCompULY, getImgHeight, getImgULX, getImgULY, getImgWidth, getNomRangeBits, getNomTileHeight, getNomTileWidth, getNumComps, getNumTiles, getNumTiles, getTile, getTileCompHeight, getTileCompWidth, getTileHeight, getTileIdx, getTilePartULX, getTilePartULY, getTileWidth, nextTile, setTile

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

OPT_PREFIX

public static final char OPT_PREFIX

The prefix for rate allocation options: 'A'

See Also:

Constant Field Values

pinfo

private static final String[][] pinfo

The list of parameters that is accepted for entropy coding. Options for entropy coding start with 'R'.

src

protected CodedCBlkDataSrcEnc src

The source of entropy coded data

wp

protected J2KImageWriteParamJava wp

The source of entropy coded data

numLayers

protected int numLayers

The number of layers.

bsWriter

CodestreamWriter bsWriter

The bit-stream writer

headEnc

HeaderEncoder headEnc

The header encoder

Constructor Detail

PostCompRateAllocator

public PostCompRateAllocator(CodedCBlkDataSrcEnc src,
                             int nl,
                             CodestreamWriter bw,
                             J2KImageWriteParamJava wp)

Initializes the source of entropy coded data.

Parameters:

src - The source of entropy coded data.

nl - The number of layers to create

bw - The packet bit stream writer.

wp - The parameters list

See Also:

ProgressionType

Method Detail

setHeaderEncoder

public void setHeaderEncoder(HeaderEncoder headEnc)

Keep a reference to the header encoder.

Parameters:

headEnc - The header encoder

initialize

public abstract void initialize()
                         throws IOException

Initializes the rate allocation points, taking into account header overhead and such. This method must be called after the header has been simulated but before calling the runAndWrite() one. The header must be rewritten after a call to this method since the number of layers may change.

Throws:

IOException

See Also:

runAndWrite()

runAndWrite

public abstract void runAndWrite()
                          throws IOException

Runs the rate allocation algorithm and writes the data to the bit stream. This must be called after the initialize() method.

Throws:

IOException

See Also:

initialize()

getNumLayers

public int getNumLayers()

Returns the number of layers that are actually generated.

Returns:

The number of layers generated.

getParameterInfo

public static String[][] getParameterInfo()

Returns the parameters that are used in this class and implementing classes. It returns a 2D String array. Each of the 1D arrays is for a different option, and they have 3 elements. The first element is the option name, the second one is the synopsis, the third one is a long description of what the parameter is and the fourth is its default value. The synopsis or description may be 'null', in which case it is assumed that there is no synopsis or description of the option, respectively. Null may be returned if no options are supported.

Returns:

the options name, their synopsis and their explanation, or null if no options are supported.

createInstance

public static PostCompRateAllocator createInstance(CodedCBlkDataSrcEnc src,
                                                   float rate,
                                                   CodestreamWriter bw,
                                                   J2KImageWriteParamJava wp)

Creates a PostCompRateAllocator object for the appropriate rate allocation parameters in the parameter list 'pl', having 'src' as the source of entropy coded data, 'rate' as the target bitrate and 'bw' as the bit stream writer object.

Parameters:

src - The source of entropy coded data.

rate - The target bitrate for the rate allocation

bw - The bit stream writer object, where the bit stream data will be written.

wp - The parameter list (or options).

parseAlayers

private static LayersInfo parseAlayers(String params,
                                       float rate)

Convenience method that parses the 'Alayers' option.

Parameters:

params - The parameters of the 'Alayers' option

rate - The overall target bitrate

Returns:

The layer specification.