jj2000.j2k.codestream.reader

Class HeaderDecoder

java.lang.Object

jj2000.j2k.codestream.reader.HeaderDecoder

All Implemented Interfaces:

Markers, ProgressionType, StdEntropyCoderOptions

public class HeaderDecoder
extends Object
implements ProgressionType, Markers, StdEntropyCoderOptions

This class reads Main and Tile-part headers from the codestream. It is created by the run() method of the Decoder instance.

A marker segment includes a marker and eventually marker segment parameters. It is designed by the three letters code of the marker associated with the marker segment. JPEG 2000 part 1 defines 6 types of markers:

• Delimiting : SOC,SOT (read in FileBitstreamReaderAgent),SOD,EOC (read in FileBitstreamReaderAgent).
• Fixed information: SIZ.
• Functional: COD,COC,RGN,QCD,QCC,POC.
• In bit-stream: SOP,EPH.
• Pointer: TLM,PLM,PLT,PPM,PPT.
• Informational: CRG,COM.

The main header is read when the constructor is called whereas tile-part headers are read when the FileBitstreamReaderAgent instance is created. The reading is done in 2 passes:

• All marker segments are buffered and their corresponding flag is activated (extractMainMarkSeg and extractTilePartMarkSeg methods).
• Buffered marker segment are analyzed in a logical way and specifications are stored in appropriate member of DecoderSpecs instance (readFoundMainMarkSeg and readFoundTilePartMarkSeg methods).

Whenever a marker segment is not recognized a warning message is displayed and its length parameter is used to skip it.

See Also:

DecoderSpecs, Decoder, FileBitstreamReaderAgent

Field Summary

Fields

Modifier and Type	Field and Description
static int	CRG_FOUND Flag bit for CRG marker segment found
int	mainHeadOff The offset of the main header in the input stream
int[]	nTileParts The number of tile parts per tile
static char	OPT_PREFIX The prefix for header decoder options: 'H'
static int	PPM_FOUND Flag bit for SOD marker segment found
static int	PPT_FOUND Flag bit for SOD marker segment found
static int	SOD_FOUND Flag bit for SOD marker segment found
Vector	tileOfTileParts Vector containing info as to which tile each tilepart belong

Fields inherited from interface jj2000.j2k.codestream.ProgressionType

COMP_POS_RES_LY_PROG, LY_RES_COMP_POS_PROG, POS_COMP_RES_LY_PROG, RES_LY_COMP_POS_PROG, RES_POS_COMP_LY_PROG

Fields inherited from interface jj2000.j2k.codestream.Markers

COC, COD, COM, CRG, EOC, EPH, EPH_LENGTH, ERS_SEG_SYMBOLS, ERS_SOP, MAX_COMP_BITDEPTH, MAX_LPPM, MAX_LPPT, PLM, PLT, POC, PPM, PPT, PRECINCT_PARTITION_DEF_SIZE, QCC, QCD, RCOM_GEN_USE, RGN, RSIZ_BASELINE, RSIZ_ER_FLAG, RSIZ_ROI, SCOX_HOR_CB_PART, SCOX_PRECINCT_PARTITION, SCOX_USE_EPH, SCOX_USE_SOP, SCOX_VER_CB_PART, SIZ, SOC, SOD, SOP, SOP_LENGTH, SOT, SQCX_EXP_MASK, SQCX_EXP_SHIFT, SQCX_GB_MSK, SQCX_GB_SHIFT, SQCX_NO_QUANTIZATION, SQCX_SCALAR_DERIVED, SQCX_SCALAR_EXPOUNDED, SRGN_IMPLICIT, SSIZ_DEPTH_BITS, TLM

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
HeaderDecoder(RandomAccessIO ehs, J2KImageReadParamJava j2krparam, HeaderInfo hi) Creates a HeaderDecoder instance and read in two passes the main header of the codestream.

Method Summary

Methods

Modifier and Type	Method and Description
void	checkMarkerLength(DataInputStream ehs, String str) Checks that the marker segment length is correct.
Dequantizer	createDequantizer(CBlkQuantDataSrcDec src, int[] rb, DecoderSpecs decSpec2) Returns the dequantizer parameters.
EntropyDecoder	createEntropyDecoder(CodedCBlkDataSrcDec src, J2KImageReadParamJava j2krparam) Creates and returns the entropy decoder corresponding to the information read from the codestream header and with the special additional parameters from the parameter list.
ROIDeScaler	createROIDeScaler(CBlkQuantDataSrcDec src, J2KImageReadParamJava j2krparam, DecoderSpecs decSpec2) Creates and returns the ROIDeScaler corresponding to the information read from the codestream header and with the special additional parameters from the parameter list.
void	extractTilePartMarkSeg(short marker, RandomAccessIO ehs, int tileIdx, int tilePartIdx) This method extracts a marker segment in a tile-part header and stores it into a byte buffer for the second pass.
int	getCbULX() Returns the horizontal code-block partition origin.Allowable values are 0 and 1, nothing else.
int	getCbULY() Returns the vertical code-block partition origin.
int	getCompSubsX(int c) Returns the component sub-sampling factor, with respect to the reference grid, along the horizontal direction for the specified component.
int	getCompSubsY(int c) Returns the component sub-sampling factor, with respect to the reference grid, along the vertical direction for the specified component.
DecoderSpecs	getDecoderSpecs() Return the DecoderSpecs instance filled when reading the headers
int	getImgHeight() Returns the image height in the reference grid.
int	getImgULX() Return the horizontal upper-left coordinate of the image in the reference grid.
int	getImgULY() Return the vertical upper-left coordinate of the image in the reference grid.
int	getImgWidth() Returns the image width in the reference grid.
int	getMaxCompImgHeight() Return the maximum height among all components
int	getMaxCompImgWidth() Return the maximum width among all components
int	getNomTileHeight() Returns the nominal width of the tiles in the reference grid.
int	getNomTileWidth() Returns the nominal width of the tiles in the reference grid.
int	getNumComps() Returns the number of components in the image.
int	getNumFoundMarkSeg() Returns the number of found marker segments in the current header.
int	getNumTiles() Return the number of tiles in the image
int	getOriginalBitDepth(int c) Returns the original bitdepth of the specified component.
ByteArrayInputStream	getPackedPktHead(int tile) Return the packed packet headers for a given tile.
static String[][]	getParameterInfo() Returns the parameters that are used in this class.
int	getPPX(int t, int c, int rl) Returns the precinct partition width for the specified tile-component and resolution level.
int	getPPY(int t, int c, int rl) Returns the precinct partition height for the specified component, tile and resolution level.
Point	getTilingOrigin(Point co) Returns the tiling origin, referred to as '(Px,Py)' in the 'ImgData' interface.
boolean	isOriginalSigned(int c) Returns true if the original data of the specified component was signed.
boolean	precinctPartitionUsed() Returns the boolean used to know if the precinct partition is used
void	readFoundTilePartMarkSeg(int tileIdx, int tpIdx) Return the DecoderSpecs instance filled when reading the headers
void	resetHeaderMarkers() Method that resets members indicating which markers have already been found
void	setTileOfTileParts(int tile) Sets the tile of each tile part in order.
String	toString() Print information about the current header.

Methods inherited from class java.lang.Object

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

Field Detail

OPT_PREFIX

public static final char OPT_PREFIX

The prefix for header decoder options: 'H'

See Also:

Constant Field Values

nTileParts

public int[] nTileParts

The number of tile parts per tile

SOD_FOUND

public static final int SOD_FOUND

Flag bit for SOD marker segment found

See Also:

Constant Field Values

PPM_FOUND

public static final int PPM_FOUND

Flag bit for SOD marker segment found

See Also:

Constant Field Values

PPT_FOUND

public static final int PPT_FOUND

Flag bit for SOD marker segment found

See Also:

Constant Field Values

CRG_FOUND

public static final int CRG_FOUND

Flag bit for CRG marker segment found

See Also:

Constant Field Values

mainHeadOff

public int mainHeadOff

The offset of the main header in the input stream

tileOfTileParts

public Vector tileOfTileParts

Vector containing info as to which tile each tilepart belong

Constructor Detail

HeaderDecoder

public HeaderDecoder(RandomAccessIO ehs,
             J2KImageReadParamJava j2krparam,
             HeaderInfo hi)
              throws IOException

Creates a HeaderDecoder instance and read in two passes the main header of the codestream. The first and last marker segments shall be respectively SOC and SOT.

Parameters:

ehs - The encoded header stream where marker segment are extracted.

j2krparam - The parameter list of the decoder

hi - The HeaderInfo holding information found in marker segments

Throws:

IOException - If an I/O error occurs while reading from the encoded header stream.

EOFException - If the end of the encoded header stream is reached before getting all the data.

CorruptedCodestreamException - If invalid data is found in the codestream main header.

Method Detail

getMaxCompImgHeight

public int getMaxCompImgHeight()

Return the maximum height among all components

Returns:

Maximum component height

getMaxCompImgWidth

public int getMaxCompImgWidth()

Return the maximum width among all components

Returns:

Maximum component width

getImgWidth

public final int getImgWidth()

Returns the image width in the reference grid.

Returns:

The image width in the reference grid

getImgHeight

public final int getImgHeight()

Returns the image height in the reference grid.

Returns:

The image height in the reference grid

getImgULX

public final int getImgULX()

Return the horizontal upper-left coordinate of the image in the reference grid.

Returns:

The horizontal coordinate of the image origin.

getImgULY

public final int getImgULY()

Return the vertical upper-left coordinate of the image in the reference grid.

Returns:

The vertical coordinate of the image origin.

getNomTileWidth

public final int getNomTileWidth()

Returns the nominal width of the tiles in the reference grid.

Returns:

The nominal tile width, in the reference grid.

getNomTileHeight

public final int getNomTileHeight()

Returns the nominal width of the tiles in the reference grid.

Returns:

The nominal tile width, in the reference grid.

getTilingOrigin

public final Point getTilingOrigin(Point co)

Returns the tiling origin, referred to as '(Px,Py)' in the 'ImgData' interface.

Parameters:

co - If not null this object is used to return the information. If null a new one is created and returned.

Returns:

The coordinate of the tiling origin, in the canvas system, on the reference grid.

See Also:

ImgData

isOriginalSigned

public final boolean isOriginalSigned(int c)

Returns true if the original data of the specified component was signed. If the data was not signed a level shift has to be applied at the end of the decompression chain.

Parameters:

c - The index of the component

Returns:

True if the original image component was signed.

getOriginalBitDepth

public final int getOriginalBitDepth(int c)

Returns the original bitdepth of the specified component.

Parameters:

c - The index of the component

Returns:

The bitdepth of the component

getNumComps

public final int getNumComps()

Returns the number of components in the image.

Returns:

The number of components in the image.

getCompSubsX

public final int getCompSubsX(int c)

Returns the component sub-sampling factor, with respect to the reference grid, along the horizontal direction for the specified component.

Parameters:

c - The index of the component

Returns:

The component sub-sampling factor X-wise.

getCompSubsY

public final int getCompSubsY(int c)

Returns the component sub-sampling factor, with respect to the reference grid, along the vertical direction for the specified component.

Parameters:

c - The index of the component

Returns:

The component sub-sampling factor Y-wise.

createDequantizer

public final Dequantizer createDequantizer(CBlkQuantDataSrcDec src,
                            int[] rb,
                            DecoderSpecs decSpec2)

Returns the dequantizer parameters. Dequantizer parameters normally are the quantization step sizes, see DequantizerParams.

Parameters:

src - The source of data for the dequantizer.

rb - The number of range bits for each component. Must be the number of range bits of the mixed components.

decSpec2 - The DecoderSpecs instance after any image manipulation.

Returns:

The dequantizer

getCbULX

public final int getCbULX()

Returns the horizontal code-block partition origin.Allowable values are 0 and 1, nothing else.

getCbULY

public final int getCbULY()

Returns the vertical code-block partition origin. Allowable values are 0 and 1, nothing else.

getPPX

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

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

Parameters:

c - the component index

t - the tile index

rl - the resolution level

Returns:

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

getPPY

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

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

Parameters:

c - the component

t - the tile index

rl - the resolution level

Returns:

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

precinctPartitionUsed

public final boolean precinctPartitionUsed()

Returns the boolean used to know if the precinct partition is used

checkMarkerLength

public void checkMarkerLength(DataInputStream ehs,
                     String str)
                       throws IOException

Checks that the marker segment length is correct.

Parameters:

ehs - The encoded header stream

str - The string identifying the marker, such as "SIZ marker"

Throws:

IOException - If an I/O error occurs

extractTilePartMarkSeg

public void extractTilePartMarkSeg(short marker,
                          RandomAccessIO ehs,
                          int tileIdx,
                          int tilePartIdx)
                            throws IOException

This method extracts a marker segment in a tile-part header and stores it into a byte buffer for the second pass. The marker is first recognized, then its flag is activated and, finally, its content is buffered in an element of byte arrays accessible thanks to a hashTable. If a marker segment is not recognized, it prints a warning and skip it according to its length.

Parameters:

marker - The marker to process

ehs - The encoded header stream

tileIdx - The index of the current tile

tilePartIdx - The index of the current tile part

Throws:

IOException

readFoundTilePartMarkSeg

public void readFoundTilePartMarkSeg(int tileIdx,
                            int tpIdx)
                              throws IOException

Return the DecoderSpecs instance filled when reading the headers

Parameters:

tileIdx - The index of the current tile

tpIdx - Index of the current tile-part

Throws:

IOException

getDecoderSpecs

public DecoderSpecs getDecoderSpecs()

Return the DecoderSpecs instance filled when reading the headers

Returns:

The DecoderSpecs of the decoder

createEntropyDecoder

public EntropyDecoder createEntropyDecoder(CodedCBlkDataSrcDec src,
                                  J2KImageReadParamJava j2krparam)

Creates and returns the entropy decoder corresponding to the information read from the codestream header and with the special additional parameters from the parameter list.

Parameters:

src - The bit stream reader agent where to get code-block data from.

j2krparam - The parameter list containing parameters applicable to the entropy decoder (other parameters can also be present).

Returns:

The entropy decoder

createROIDeScaler

public ROIDeScaler createROIDeScaler(CBlkQuantDataSrcDec src,
                            J2KImageReadParamJava j2krparam,
                            DecoderSpecs decSpec2)

Creates and returns the ROIDeScaler corresponding to the information read from the codestream header and with the special additional parameters from the parameter list.

Parameters:

src - The bit stream reader agent where to get code-block data from.

pl - The parameter list containing parameters applicable to the entropy decoder (other parameters can also be present).

Returns:

The ROI descaler

resetHeaderMarkers

public void resetHeaderMarkers()

Method that resets members indicating which markers have already been found

toString

public String toString()

Print information about the current header.

Overrides:

toString in class Object

Returns:

Information in a String

getParameterInfo

public static String[][] getParameterInfo()

Returns the parameters that are used in this class. 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 and the third one is a long description of what the parameter is. The synopsis or description may be 'null', in which case it is assumed that there is no synopsis or description of the option, respectively.

Returns:

the options name, their synopsis and their explanation.

getNumTiles

public int getNumTiles()

Return the number of tiles in the image

Returns:

The number of tiles

getPackedPktHead

public ByteArrayInputStream getPackedPktHead(int tile)
                                      throws IOException

Return the packed packet headers for a given tile.

Returns:

An input stream containing the packed packet headers for a particular tile

Throws:

IOException - If an I/O error occurs while reading from the encoder header stream

setTileOfTileParts

public void setTileOfTileParts(int tile)

Sets the tile of each tile part in order. This information is needed for identifying which packet header belongs to which tile when using the PPM marker.

Parameters:

tile - The tile number that the present tile part belongs to.

getNumFoundMarkSeg

public int getNumFoundMarkSeg()

Returns the number of found marker segments in the current header.

Returns:

The number of marker segments found in the current header.