jj2000.j2k.codestream.writer

Class PktEncoder

java.lang.Object

jj2000.j2k.codestream.writer.PktEncoder

public class PktEncoder
extends Object

This class builds packets and keeps the state information of packet interdependencies. It also supports saving the state and reverting (restoring) to the last saved state, with the save() and restore() methods.

Each time the encodePacket() method is called a new packet is encoded, the packet header is returned by the method, and the packet body can be obtained with the getLastBodyBuf() and getLastBodyLen() methods.

Field Summary

Fields

Modifier and Type	Field and Description
static char	OPT_PREFIX The prefix for packet encoding options: 'P'

Constructor Summary

Constructors

Constructor and Description
PktEncoder(CodedCBlkDataSrcEnc infoSrc, J2KImageWriteParamJava wp, Point[][][] numPrec) Creates a new packet header encoder, using the information from the 'infoSrc' object.

Method Summary

Modifier and Type	Method and Description
BitOutputBuffer	encodePacket(int ly, int c, int r, int t, CBlkRateDistStats[][] cbs, int[][] tIndx, BitOutputBuffer hbuf, byte[] bbuf, int pIdx) Encodes a packet and returns the buffer containing the encoded packet header.
byte[]	getLastBodyBuf() Returns the buffer of the body of the last encoded packet.
int	getLastBodyLen() Returns the length of the body of the last encoded packet, in bytes.
static String[][]	getParameterInfo() Returns the parameters that are used in this class and implementing classes.
PrecInfo	getPrecInfo(int t, int c, int r, int p) Returns information about a given precinct
int	getROILen() Gives the length to read in current packet body to get all ROI information
boolean	isPacketWritable() Returns true if the current packet is writable i.e.
boolean	isROIinPkt() Tells if there was ROI information in the last written packet
void	reset() Resets the state of the object to the initial state, as if the object was just created.
void	restore() Restores the last saved state of this object.
void	save() Saves the current state of this object.

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 packet encoding options: 'P'

See Also:

Constant Field Values

Constructor Detail

PktEncoder

public PktEncoder(CodedCBlkDataSrcEnc infoSrc,
                  J2KImageWriteParamJava wp,
                  Point[][][] numPrec)

Creates a new packet header encoder, using the information from the 'infoSrc' object. The information used is the number of components, number of tiles, subband decomposition, etc.

Note that this constructor visits all the tiles in the 'infoSrc' object. The 'infoSrc' object is left at the original tile (i.e. the current tile before calling this constructor), but any side effects of visiting the tiles is not reverted.

Parameters:

infoSrc - The source of information to construct the object.

encSpec - The parameters for the encoding

maxNumPrec - Maximum number of precinct in each tile, component and resolution level.

pl - ParameterList instance that holds command line options

Method Detail

encodePacket

public BitOutputBuffer encodePacket(int ly,
                                    int c,
                                    int r,
                                    int t,
                                    CBlkRateDistStats[][] cbs,
                                    int[][] tIndx,
                                    BitOutputBuffer hbuf,
                                    byte[] bbuf,
                                    int pIdx)

Encodes a packet and returns the buffer containing the encoded packet header. The code-blocks appear in a 3D array of CBlkRateDistStats, 'cbs'. The first index is the tile index in lexicographical order, the second index is the subband index (as defined in the Subband class), and the third index is the code-block index (whithin the subband tile) in lexicographical order as well. The indexes of the new truncation points for each code-block are specified by the 3D array of int 'tIndx'. The indices of this array are the same as for cbs. The truncation point indices in 'tIndx' are the indices of the elements of the 'truncIdxs' array, of the CBlkRateDistStats class, that give the real truncation points. If a truncation point index is negative it means that the code-block has not been included in any layer yet. If the truncation point is less than or equal to the highest truncation point used in previous layers then the code-block is not included in the packet. Otherwise, if larger, the code-block is included in the packet. The body of the packet can be obtained with the getLastBodyBuf() and getLastBodyLen() methods.

Layers must be coded in increasing order, in consecutive manner, for each tile, component and resolution level (e.g., layer 1, then layer 2, etc.). For different tile, component and/or resolution level no particular order must be followed.

Parameters:

ly - The layer index (starts at 1).

c - The component index.

r - The resolution level

t - Index of the current tile

cbs - The 3D array of coded code-blocks.

tIndx - The truncation point indices for each code-block.

hbuf - The header buffer. If null a new BitOutputBuffer is created and returned. This buffer is reset before anything is written to it.

bbuf - The body buffer. If null a new one is created. If not large enough a new one is created.

pIdx - The precinct index.

Returns:

The buffer containing the packet header.

getLastBodyBuf

public byte[] getLastBodyBuf()

Returns the buffer of the body of the last encoded packet. The length of the body can be retrieved with the getLastBodyLen() method. The length of the array returned by this method may be larger than the actual body length.

Returns:

The buffer of body of the last encoded packet.

Throws:

IllegalArgumentException - If no packet has been coded since last reset(), last restore(), or object creation.

See Also:

getLastBodyLen()

getLastBodyLen

public int getLastBodyLen()

Returns the length of the body of the last encoded packet, in bytes. The body itself can be retrieved with the getLastBodyBuf() method.

Returns:

The length of the body of last encoded packet, in bytes.

See Also:

getLastBodyBuf()

save

public void save()

Saves the current state of this object. The last saved state can be restored with the restore() method.

See Also:

restore()

restore

public void restore()

Restores the last saved state of this object. An IllegalArgumentException is thrown if no state has been saved.

See Also:

save()

reset

public void reset()

Resets the state of the object to the initial state, as if the object was just created.

isPacketWritable

public boolean isPacketWritable()

Returns true if the current packet is writable i.e. should be written. Returns false otherwise.

isROIinPkt

public boolean isROIinPkt()

Tells if there was ROI information in the last written packet

getROILen

public int getROILen()

Gives the length to read in current packet body to get all ROI information

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.

getPrecInfo

public PrecInfo getPrecInfo(int t,
                            int c,
                            int r,
                            int p)

Returns information about a given precinct

Parameters:

t - Tile index.

c - Component index.

r - Resolution level index.

p - Precinct index