jj2000.j2k.codestream.writer

Class HeaderEncoder

java.lang.Object

jj2000.j2k.codestream.writer.HeaderEncoder

All Implemented Interfaces:

Markers, StdEntropyCoderOptions

public class HeaderEncoder
extends Object
implements Markers, StdEntropyCoderOptions

This class writes almost of the markers and marker segments in main header and in tile-part headers. It is created by the run() method of the Encoder instance.

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

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

Main Header is written when Encoder instance calls encodeMainHeader whereas tile-part headers are written when the EBCOTRateAllocator instance calls encodeTilePartHeader.

See Also:

Encoder, Markers, EBCOTRateAllocator

Field Summary

Fields

Modifier and Type	Field and Description
protected ByteArrayOutputStream	baos The ByteArrayOutputStream to store header data.
protected ForwardWT	dwt Reference to the DWT module
protected DataOutputStream	hbuf The DataOutputStream to store header data.
protected boolean[]	isOrigSig An array specifying, for each component,if the data was signed or not
protected int	nComp The number of components in the image
protected ImgData	origSrc The image data reader.
protected PostCompRateAllocator	ralloc Reference to the rate allocator
protected ROIScaler	roiSc Reference to the ROI module
protected Tiler	tiler Reference to the tiler module
protected J2KImageWriteParamJava	wp The encoder specifications

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
HeaderEncoder(ImgData origsrc, boolean[] isorigsig, ForwardWT dwt, Tiler tiler, J2KImageWriteParamJava wp, ROIScaler roiSc, PostCompRateAllocator ralloc) Initializes the header writer with the references to the coding chain.

Method Summary

Modifier and Type	Method and Description
void	encodeMainHeader() Write main header.
void	encodeTilePartHeader(int tileLength, int tileIdx) Writes tile-part header.
protected byte[]	getBuffer() Returns the byte-buffer used to store the codestream header.
protected int	getBufferLength() Returns the number of bytes used in the codestream header's buffer.
int	getLength() Returns the length of the header.
void	reset() Resets the contents of this HeaderEncoder to its initial state.
protected void	writeCOC(boolean mh, int tileIdx, int compIdx) Writes COC marker segment .
protected void	writeCOD(boolean mh, int tileIdx) Writes COD marker segment.
protected void	writeMainQCC(int compIdx) Writes QCC marker segment in main header.
protected void	writeMainQCD() Writes QCD marker segment in main header.
protected void	writePOC(boolean mh, int tileIdx) Writes POC marker segment.
protected void	writeTileQCC(int t, int compIdx) Writes QCC marker segment in tile header.
protected void	writeTileQCD(int tIdx) Writes QCD marker segment in tile header.
void	writeTo(BinaryDataOutput out) Writes the header to the specified BinaryDataOutput.
void	writeTo(OutputStream out) Writes the header to the specified OutputStream.

Methods inherited from class java.lang.Object

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

Field Detail

nComp

protected int nComp

The number of components in the image

baos

protected ByteArrayOutputStream baos

The ByteArrayOutputStream to store header data. This handler is kept in order to use methods not accessible from a general DataOutputStream. For the other methods, it's better to use variable hbuf.

See Also:

hbuf

hbuf

protected DataOutputStream hbuf

The DataOutputStream to store header data. This kind of object is useful to write short, int, .... It's constructor takes baos as parameter.

See Also:

baos

origSrc

protected ImgData origSrc

The image data reader. Source of original data info

isOrigSig

protected boolean[] isOrigSig

An array specifying, for each component,if the data was signed or not

ralloc

protected PostCompRateAllocator ralloc

Reference to the rate allocator

dwt

protected ForwardWT dwt

Reference to the DWT module

tiler

protected Tiler tiler

Reference to the tiler module

roiSc

protected ROIScaler roiSc

Reference to the ROI module

wp

protected J2KImageWriteParamJava wp

The encoder specifications

Constructor Detail

HeaderEncoder

public HeaderEncoder(ImgData origsrc,
                     boolean[] isorigsig,
                     ForwardWT dwt,
                     Tiler tiler,
                     J2KImageWriteParamJava wp,
                     ROIScaler roiSc,
                     PostCompRateAllocator ralloc)

Initializes the header writer with the references to the coding chain.

Parameters:

origsrc - The original image data (before any component mixing, tiling, etc.)

isorigsig - An array specifying for each component if it was originally signed or not.

dwt - The discrete wavelet transform module.

tiler - The tiler module.

encSpec - The encoder specifications

roiSc - The ROI scaler module.

ralloc - The post compression rate allocator.

Method Detail

reset

public void reset()

Resets the contents of this HeaderEncoder to its initial state. It erases all the data in the header buffer and reactualizes the headerLength field of the bit stream writer.

getBuffer

protected byte[] getBuffer()

Returns the byte-buffer used to store the codestream header.

Returns:

A byte array countaining codestream header

getLength

public int getLength()

Returns the length of the header.

Returns:

The length of the header in bytes

writeTo

public void writeTo(BinaryDataOutput out)
             throws IOException

Writes the header to the specified BinaryDataOutput.

Parameters:

out - Where to write the header.

Throws:

IOException

getBufferLength

protected int getBufferLength()

Returns the number of bytes used in the codestream header's buffer.

Returns:

Header length in buffer (without any header overhead)

writeTo

public void writeTo(OutputStream out)
             throws IOException

Writes the header to the specified OutputStream.

Parameters:

out - Where to write the header.

Throws:

IOException

writeCOD

protected void writeCOD(boolean mh,
                        int tileIdx)
                 throws IOException

Writes COD marker segment. COD is a functional marker segment containing the code style default (coding style, decomposition, layering) used for compressing all the components in an image.

The values can be overriden for an individual component by a COC marker in either the main or the tile header.

Parameters:

mh - Flag indicating whether this marker belongs to the main header

tileIdx - Tile index if the marker belongs to a tile-part header

Throws:

IOException

See Also:

writeCOC(boolean, int, int)

writeCOC

protected void writeCOC(boolean mh,
                        int tileIdx,
                        int compIdx)
                 throws IOException

Writes COC marker segment . It is a functional marker containing the coding style for one component (coding style, decomposition, layering).

Its values overrides any value previously set in COD in the main header or in the tile header.

Parameters:

mh - Flag indicating whether the main header is to be written

tileIdx - Tile index

compIdx - index of the component which need use of the COC marker segment.

Throws:

IOException

See Also:

writeCOD(boolean, int)

writeMainQCD

protected void writeMainQCD()
                     throws IOException

Writes QCD marker segment in main header. QCD is a functional marker segment countaining the quantization default used for compressing all the components in an image. The values can be overriden for an individual component by a QCC marker in either the main or the tile header.

Throws:

IOException

writeMainQCC

protected void writeMainQCC(int compIdx)
                     throws IOException

Writes QCC marker segment in main header. It is a functional marker segment countaining the quantization used for compressing the specified component in an image. The values override for the specified component what was defined by a QCC marker in either the main or the tile header.

Parameters:

compIdx - Index of the component which needs QCC marker segment.

Throws:

IOException

writeTileQCD

protected void writeTileQCD(int tIdx)
                     throws IOException

Writes QCD marker segment in tile header. QCD is a functional marker segment countaining the quantization default used for compressing all the components in an image. The values can be overriden for an individual component by a QCC marker in either the main or the tile header.

Parameters:

tIdx - Tile index

Throws:

IOException

writeTileQCC

protected void writeTileQCC(int t,
                            int compIdx)
                     throws IOException

Writes QCC marker segment in tile header. It is a functional marker segment countaining the quantization used for compressing the specified component in an image. The values override for the specified component what was defined by a QCC marker in either the main or the tile header.

Parameters:

t - Tile index

compIdx - Index of the component which needs QCC marker segment.

Throws:

IOException

writePOC

protected void writePOC(boolean mh,
                        int tileIdx)
                 throws IOException

Writes POC marker segment. POC is a functional marker segment containing the bounds and progression order for any progression order other than default in the codestream.

Parameters:

mh - Flag indicating whether the main header is to be written

tileIdx - Tile index

Throws:

IOException

encodeMainHeader

public void encodeMainHeader()
                      throws IOException

Write main header. JJ2000 main header corresponds to the following sequence of marker segments:

1. SOC
2. SIZ
3. COD
4. COC (if needed)
5. QCD
6. QCC (if needed)
7. POC (if needed)

Throws:

IOException

encodeTilePartHeader

public void encodeTilePartHeader(int tileLength,
                                 int tileIdx)
                          throws IOException

Writes tile-part header. JJ2000 tile-part header corresponds to the following sequence of marker segments:

1. SOT
2. COD (if needed)
3. COC (if needed)
4. QCD (if needed)
5. QCC (if needed)
6. RGN (if needed)
7. POC (if needed)
8. SOD

Parameters:

length - The length of the current tile-part.

tileIdx - Index of the tile to write

Throws:

IOException