jj2000.j2k.entropy.encoder

Class StdEntropyCoder

java.lang.Object

jj2000.j2k.image.ImgDataAdapter

jj2000.j2k.entropy.encoder.EntropyCoder

jj2000.j2k.entropy.encoder.StdEntropyCoder

All Implemented Interfaces:

CodedCBlkDataSrcEnc, StdEntropyCoderOptions, ImgData, ForwWTDataProps

public class StdEntropyCoder
extends EntropyCoder
implements StdEntropyCoderOptions

This class implements the JPEG 2000 entropy coder, which codes stripes in code-blocks. This entropy coding engine can function in a single-threaded mode where one code-block is encoded at a time, or in a multi-threaded mode where multiple code-blocks are entropy coded in parallel. The interface presented by this class is the same in both modes.

The number of threads used by this entropy coder is specified by the "jj2000.j2k.entropy.encoder.StdEntropyCoder.nthreads" Java system property. If set to "0" the single threaded implementation is used. If set to 'n' ('n' larger than 0) then 'n' extra threads are started by this class which are used to encode the code-blocks in parallel (i.e. ideally 'n' code-blocks will be encoded in parallel at a time). On multiprocessor machines under a "native threads" Java Virtual Machine implementation each one of these threads can run on a separate processor speeding up the encoding time. By default the single-threaded implementation is used. The multi-threaded implementation currently assumes that the vast majority of consecutive calls to 'getNextCodeBlock()' will be done on the same component. If this is not the case, the speed-up that can be expected on multiprocessor machines might be significantly decreased.

The code-blocks are rectangular, with dimensions which must be powers of 2. Each dimension has to be no smaller than 4 and no larger than 256. The product of the two dimensions (i.e. area of the code-block) may not exceed 4096.

Context 0 of the MQ-coder is used as the uniform one (uniform, non-adaptive probability distribution). Context 1 is used for RLC coding. Contexts 2-10 are used for zero-coding (ZC), contexts 11-15 are used for sign-coding (SC) and contexts 16-18 are used for magnitude-refinement (MR).

This implementation buffers the symbols and calls the MQ coder only once per stripe and per coding pass, to reduce the method call overhead.

This implementation also provides some timing features. They can be enabled by setting the 'DO_TIMING' constant of this class to true and recompiling. The timing uses the 'System.currentTimeMillis()' Java API call, which returns wall clock time, not the actual CPU time used. The timing results will be printed on the message output. Since the times reported are wall clock times and not CPU usage times they can not be added to find the total used time (i.e. some time might be counted in several places). When timing is disabled ('DO_TIMING' is false) there is no penalty if the compiler performs some basic optimizations. Even if not the penalty should be negligeable.

The source module must implement the CBlkQuantDataSrcEnc interface and code-block's data is received in a CBlkWTData instance. This modules sends code-block's information in a CBlkRateDistStats instance.

See Also:

CBlkQuantDataSrcEnc, CBlkWTData, CBlkRateDistStats

Field Summary

Fields

Modifier and Type	Field and Description
StringSpec	bms By-pass mode specifications
StringSpec	css Causal stripes specifications
static String	DEF_THREADS_NUM The default value for the property in THREADS_PROP_NAME: 0
StringSpec	lcs The length calculation specifications
StringSpec	mqrs MQ reset specifications
StringSpec	rts Regular termination specifications
StringSpec	sss Error resilience segment symbol use specifications
static int	THREADS_PRIORITY_INC The increase in priority for the compressor threads, currently 3.
static String	THREADS_PROP_NAME The Java system property name for the number of threads to use: jj2000.j2k.entropy.encoder.StdEntropyCoder.nthreads
StringSpec	tts The termination type specifications

Fields inherited from class jj2000.j2k.entropy.encoder.EntropyCoder

OPT_PREFIX, src

Fields inherited from class jj2000.j2k.image.ImgDataAdapter

imgdatasrc, tIdx

Fields inherited from interface jj2000.j2k.entropy.StdEntropyCoderOptions

FIRST_BYPASS_PASS_IDX, MAX_CB_AREA, MAX_CB_DIM, MIN_CB_DIM, NUM_EMPTY_PASSES_IN_MS_BP, NUM_NON_BYPASS_MS_BP, NUM_PASSES, OPT_BYPASS, OPT_PRED_TERM, OPT_RESET_MQ, OPT_SEG_SYMBOLS, OPT_TERM_PASS, OPT_VERT_STR_CAUSAL, STRIPE_HEIGHT

Constructor Summary

Constructors

Constructor and Description
StdEntropyCoder(CBlkQuantDataSrcEnc src, CBlkSizeSpec cblks, PrecinctSizeSpec pss, StringSpec bms, StringSpec mqrs, StringSpec rts, StringSpec css, StringSpec sss, StringSpec lcs, StringSpec tts) Instantiates a new entropy coder engine, with the specified source of data, nominal block width and height.

Method Summary

Modifier and Type	Method and Description
void	finalize() Prints the timing information, if collected, and calls 'finalize' on the super class.
int	getCBlkHeight(int t, int c) Returns the code-block height for the specified tile and component.
int	getCBlkWidth(int t, int c) Returns the code-block width for the specified tile and component.
CBlkRateDistStats	getNextCodeBlock(int c, CBlkRateDistStats ccb) Returns the next coded code-block in the current tile for the specified component, as a copy (see below).
int	getPPX(int t, int c, int rl) Returns the precinct partition width for the specified component, tile and resolution level.
int	getPPY(int t, int c, int rl) Returns the precinct partition height for the specified component, tile and resolution level.
void	initTileComp(int nt, int nc) Load options, length calculation type and termination type for each tile-component.
void	nextTile() Advances to the next tile, in standard scan-line order (by rows then columns).
boolean	precinctPartitionUsed(int c, int t) Returns true if precinct partition is used for the specified component and tile, returns false otherwise.
void	setTile(int x, int y) Changes the current tile, given the new indexes.

Methods inherited from class jj2000.j2k.entropy.encoder.EntropyCoder

createInstance, getAnSubbandTree, getCbULX, getCbULY, getParameterInfo, isReversible

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

Methods inherited from class java.lang.Object

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

Methods inherited from interface jj2000.j2k.image.ImgData

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

Field Detail

THREADS_PROP_NAME

public static final String THREADS_PROP_NAME

The Java system property name for the number of threads to use: jj2000.j2k.entropy.encoder.StdEntropyCoder.nthreads

See Also:

Constant Field Values

DEF_THREADS_NUM

public static final String DEF_THREADS_NUM

The default value for the property in THREADS_PROP_NAME: 0

See Also:

Constant Field Values

THREADS_PRIORITY_INC

public static final int THREADS_PRIORITY_INC

The increase in priority for the compressor threads, currently 3. The compressor threads will have a priority of THREADS_PRIORITY_INC more than the priority of the thread calling this class constructor. Used only in the multi-threaded implementation.

See Also:

Constant Field Values

bms

public StringSpec bms

By-pass mode specifications

mqrs

public StringSpec mqrs

MQ reset specifications

rts

public StringSpec rts

Regular termination specifications

css

public StringSpec css

Causal stripes specifications

sss

public StringSpec sss

Error resilience segment symbol use specifications

lcs

public StringSpec lcs

The length calculation specifications

tts

public StringSpec tts

The termination type specifications

Constructor Detail

StdEntropyCoder

public StdEntropyCoder(CBlkQuantDataSrcEnc src,
                       CBlkSizeSpec cblks,
                       PrecinctSizeSpec pss,
                       StringSpec bms,
                       StringSpec mqrs,
                       StringSpec rts,
                       StringSpec css,
                       StringSpec sss,
                       StringSpec lcs,
                       StringSpec tts)

Instantiates a new entropy coder engine, with the specified source of data, nominal block width and height.

If the 'OPT_PRED_TERM' option is given then the MQ termination must be 'TERM_PRED_ER' or an exception is thrown.

Parameters:

src - The source of data

cbks - Code-block size specifications

pss - Precinct partition specifications

bms - By-pass mode specifications

mqrs - MQ-reset specifications

rts - Regular termination specifications

css - Causal stripes specifications

sss - Error resolution segment symbol use specifications

lcs - Length computation specifications

tts - Termination type specifications

See Also:

MQCoder

Method Detail

finalize

public void finalize()
              throws Throwable

Prints the timing information, if collected, and calls 'finalize' on the super class.

Overrides:

finalize in class Object

Throws:

Throwable

getCBlkWidth

public int getCBlkWidth(int t,
                        int c)

Returns the code-block width for the specified tile and component.

Specified by:

getCBlkWidth in class EntropyCoder

Parameters:

t - The tile index

c - the component index

Returns:

The code-block width for the specified tile and component

getCBlkHeight

public int getCBlkHeight(int t,
                         int c)

Returns the code-block height for the specified tile and component.

Specified by:

getCBlkHeight in class EntropyCoder

Parameters:

t - The tile index

c - The component index

Returns:

The code-block height for the specified tile and component.

getNextCodeBlock

public CBlkRateDistStats getNextCodeBlock(int c,
                                          CBlkRateDistStats ccb)

Returns the next coded code-block in the current tile for the specified component, as a copy (see below). The order in which code-blocks are returned is not specified. However each code-block is returned only once and all code-blocks will be returned if the method is called 'N' times, where 'N' is the number of code-blocks in the tile. After all the code-blocks have been returned for the current tile calls to this method will return 'null'.

When changing the current tile (through 'setTile()' or 'nextTile()') this method will always return the first code-block, as if this method was never called before for the new current tile.

The data returned by this method is always a copy of the internal data of this object, if any, and it can be modified "in place" without any problems after being returned.

Specified by:

getNextCodeBlock in interface CodedCBlkDataSrcEnc

Parameters:

c - The component for which to return the next code-block.

ccb - If non-null this object might be used in returning the coded code-block in this or any subsequent call to this method. If null a new one is created and returned. If the 'data' array of 'cbb' is not null it may be reused to return the compressed data.

Returns:

The next coded code-block in the current tile for component 'n', or null if all code-blocks for the current tile have been returned.

See Also:

CBlkRateDistStats

setTile

public void setTile(int x,
                    int y)

Changes the current tile, given the new indexes. An IllegalArgumentException is thrown if the indexes do not correspond to a valid tile.

This default implementation just changes the tile in the source.

Specified by:

setTile in interface ImgData

Overrides:

setTile in class ImgDataAdapter

Parameters:

x - The horizontal index of the tile.

y - The vertical index of the new tile.

nextTile

public void nextTile()

Advances to the next tile, in standard scan-line order (by rows then columns). An NoNextElementException is thrown if the current tile is the last one (i.e. there is no next tile).

This default implementation just advances to the next tile in the source.

Specified by:

nextTile in interface ImgData

Overrides:

nextTile in class ImgDataAdapter

initTileComp

public void initTileComp(int nt,
                         int nc)

Load options, length calculation type and termination type for each tile-component.

Parameters:

nt - The number of tiles

nc - The number of components

getPPX

public int getPPX(int t,
                  int c,
                  int rl)

Returns the precinct partition width for the specified component, tile and resolution level.

Specified by:

getPPX in interface CodedCBlkDataSrcEnc

Parameters:

t - the tile index

c - the component

rl - the resolution level

Returns:

The precinct partition width for the specified component, tile and resolution level

getPPY

public int getPPY(int t,
                  int c,
                  int rl)

Returns the precinct partition height for the specified component, tile and resolution level.

Specified by:

getPPY in interface CodedCBlkDataSrcEnc

Parameters:

t - the tile index

c - the component

rl - the resolution level

Returns:

The precinct partition height for the specified component, tile and resolution level

precinctPartitionUsed

public boolean precinctPartitionUsed(int c,
                                     int t)

Returns true if precinct partition is used for the specified component and tile, returns false otherwise.

Specified by:

precinctPartitionUsed in interface CodedCBlkDataSrcEnc

Parameters:

c - The component

t - The tile

Returns:

True if precinct partition is used for the specified component and tile, returns false otherwise.