jj2000.j2k.codestream.writer

Class FileCodestreamWriter

java.lang.Object

jj2000.j2k.codestream.writer.CodestreamWriter

jj2000.j2k.codestream.writer.FileCodestreamWriter

All Implemented Interfaces:

Markers

public class FileCodestreamWriter
extends CodestreamWriter
implements Markers

This class implements a CodestreamWriter for Java streams. The streams can be files or network connections, or any other resource that presents itself as a OutputStream. See the CodestreamWriter abstract class for more details on the implementation of the CodestreamWriter abstract class.

Before any packet data is written to the bit stream (even in simulation mode) the complete header should be written to the HeaderEncoder object supplied to the constructor, following the procedure explained in the HeaderEncoder class. Otherwise incorrect estimates are given by getMaxAvailableBytes() for rate allocation.

See Also:

CodestreamWriter, HeaderEncoder

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEF_BUF_LEN The default buffer length, 1024 bytes
(package private) byte[]	ephMarker Array used to store the EPH markers values
private int	lenLastNoROI Length of last packets containing no ROI information
(package private) int	ndata The number of bytes already written to the bit stream, excluding the header length, magic number and header length info.
private int	offLastROIPkt Offset of end of last packet containing ROI information
private OutputStream	out The file to write
(package private) int	packetIdx The packet index (when start of packet markers i.e.
private static int	SOP_MARKER_LIMIT The upper limit for the value of the Nsop field of the SOP marker
(package private) byte[]	sopMarker Array used to store the SOP markers values
private int	tileIdx Index of the current tile

Fields inherited from class jj2000.j2k.codestream.writer.CodestreamWriter

maxBytes

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

Constructor Summary

Constructors

Constructor and Description
FileCodestreamWriter(File file, int mb) Opens the file 'file' for writing the bit stream, using the 'he' header encoder.
FileCodestreamWriter(OutputStream os, int mb) Uses the output stream 'os' for writing the bit stream, using the 'he' header encoder.
FileCodestreamWriter(String fname, int mb) Opens the file named 'fname' for writing the bit stream, using the 'he' header encoder.

Method Summary

Modifier and Type	Method and Description
void	close() Writes the EOC marker and closes the underlying stream.
void	commitBitstreamHeader(HeaderEncoder he) Writes the header data in the codestream and actualize ndata with the header length.
int	getLength() Returns the current length of the entire bit stream.
int	getMaxAvailableBytes() Returns the number of bytes remaining available in the bit stream.
int	getOffLastROIPkt() Gives the offset of the end of last packet containing ROI information
private void	initSOP_EPHArrays() Performs the initialisation of the arrays that are used to store the values used to write SOP and EPH markers
int	writePacketBody(byte[] body, int blen, boolean sim, boolean roiInPkt, int roiLen) Writes a packet body to the bit stream and returns the number of bytes used by this body .If in simulation mode then no data is written to the bit stream but the number of bytes is calculated.
int	writePacketHead(byte[] head, int hlen, boolean sim, boolean sop, boolean eph) Writes a packet head to the bit stream and returns the number of bytes used by this header.

Methods inherited from class java.lang.Object

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

Field Detail

SOP_MARKER_LIMIT

private static final int SOP_MARKER_LIMIT

The upper limit for the value of the Nsop field of the SOP marker

See Also:

Constant Field Values

tileIdx

private int tileIdx

Index of the current tile

out

private OutputStream out

The file to write

ndata

int ndata

The number of bytes already written to the bit stream, excluding the header length, magic number and header length info.

DEF_BUF_LEN

public static int DEF_BUF_LEN

The default buffer length, 1024 bytes

sopMarker

byte[] sopMarker

Array used to store the SOP markers values

ephMarker

byte[] ephMarker

Array used to store the EPH markers values

packetIdx

int packetIdx

The packet index (when start of packet markers i.e. SOP markers) are used.

offLastROIPkt

private int offLastROIPkt

Offset of end of last packet containing ROI information

lenLastNoROI

private int lenLastNoROI

Length of last packets containing no ROI information

Constructor Detail

FileCodestreamWriter

public FileCodestreamWriter(File file,
                            int mb)
                     throws IOException

Opens the file 'file' for writing the bit stream, using the 'he' header encoder. The magic number is written to the bit stream. Normally, the header encoder must be empty (i.e. no data has been written to it yet). A BufferedOutputStream is used on top of the file to increase throughput, the length of the buffer is DEF_BUF_LEN.

Parameters:

file - The file where to write the bit stream

mb - The maximum number of bytes that can be written to the bit stream.

Throws:

IOException - If an error occurs while trying to open the file for writing or while writing the magic number.

FileCodestreamWriter

public FileCodestreamWriter(String fname,
                            int mb)
                     throws IOException

Opens the file named 'fname' for writing the bit stream, using the 'he' header encoder. The magic number is written to the bit stream. Normally, the header encoder must be empty (i.e. no data has been written to it yet). A BufferedOutputStream is used on top of the file to increase throughput, the length of the buffer is DEF_BUF_LEN.

Parameters:

fname - The name of file where to write the bit stream

mb - The maximum number of bytes that can be written to the bit stream.

Throws:

IOException - If an error occurs while trying to open the file for writing or while writing the magic number.

FileCodestreamWriter

public FileCodestreamWriter(OutputStream os,
                            int mb)
                     throws IOException

Uses the output stream 'os' for writing the bit stream, using the 'he' header encoder. The magic number is written to the bit stream. Normally, the header encoder must be empty (i.e. no data has been written to it yet). No BufferedOutputStream is used on top of the output stream 'os'.

Parameters:

os - The output stream where to write the bit stream.

mb - The maximum number of bytes that can be written to the bit stream.

Throws:

IOException - If an error occurs while writing the magic number to the 'os' output stream.

Method Detail

getMaxAvailableBytes

public final int getMaxAvailableBytes()

Returns the number of bytes remaining available in the bit stream. This is the maximum allowed number of bytes minus the number of bytes that have already been written to the bit stream. If more bytes have been written to the bit stream than the maximum number of allowed bytes, then a negative value is returned.

Specified by:

getMaxAvailableBytes in class CodestreamWriter

Returns:

The number of bytes remaining available in the bit stream.

getLength

public int getLength()

Returns the current length of the entire bit stream.

Specified by:

getLength in class CodestreamWriter

Returns:

the current length of the bit stream

writePacketHead

public int writePacketHead(byte[] head,
                           int hlen,
                           boolean sim,
                           boolean sop,
                           boolean eph)
                    throws IOException

Writes a packet head to the bit stream and returns the number of bytes used by this header. It returns the total number of bytes that the packet head takes in the bit stream. If in simulation mode then no data is written to the bit stream but the number of bytes is calculated. This can be used for iterative rate allocation.

If the length of the data that is to be written to the bit stream is more than the space left (as returned by getMaxAvailableBytes()) only the data that does not exceed the allowed length is written, the rest is discarded. However the value returned by the method is the total length of the packet, as if all of it was written to the bit stream.

If the bit stream header has not been commited yet and 'sim' is false, then the bit stream header is automatically commited (see commitBitstreamHeader() method) before writting the packet.

Specified by:

writePacketHead in class CodestreamWriter

Parameters:

head - The packet head data.

hlen - The number of bytes in the packet head.

sim - Simulation mode flag. If true nothing is written to the bit stream, but the number of bytes that would be written is returned.

sop - Start of packet header marker flag. This flag indicates whether or not SOP markers should be written. If true, SOP markers should be written, if false, they should not.

eph - End of Packet Header marker flag. This flag indicates whether or not EPH markers should be written. If true, EPH markers should be written, if false, they should not.

Returns:

The number of bytes spent by the packet head.

Throws:

IOException - If an I/O error occurs while writing to the output stream.

See Also:

commitBitstreamHeader(jj2000.j2k.codestream.writer.HeaderEncoder)

writePacketBody

public int writePacketBody(byte[] body,
                           int blen,
                           boolean sim,
                           boolean roiInPkt,
                           int roiLen)
                    throws IOException

Writes a packet body to the bit stream and returns the number of bytes used by this body .If in simulation mode then no data is written to the bit stream but the number of bytes is calculated. This can be used for iterative rate allocation.

If the length of the data that is to be written to the bit stream is more than the space left (as returned by getMaxAvailableBytes()) only the data that does not exceed the allowed length is written, the rest is discarded. However the value returned by the method is the total length of the packet body , as if all of it was written to the bit stream.

Specified by:

writePacketBody in class CodestreamWriter

Parameters:

body - The packet body data.

blen - The number of bytes in the packet body.

sim - Simulation mode flag. If true nothing is written to the bit stream, but the number of bytes that would be written is returned.

roiInPkt - Whether or not this packet contains ROI information

roiLen - Number of byte to read in packet body to get all the ROI information

Returns:

The number of bytes spent by the packet body.

Throws:

IOException - If an I/O error occurs while writing to the output stream.

See Also:

commitBitstreamHeader(jj2000.j2k.codestream.writer.HeaderEncoder)

close

public void close()
           throws IOException

Writes the EOC marker and closes the underlying stream.

Specified by:

close in class CodestreamWriter

Throws:

IOException - If an error occurs while closing the underlying stream.

getOffLastROIPkt

public int getOffLastROIPkt()

Gives the offset of the end of last packet containing ROI information

Specified by:

getOffLastROIPkt in class CodestreamWriter

Returns:

End of last ROI packet

commitBitstreamHeader

public void commitBitstreamHeader(HeaderEncoder he)
                           throws IOException

Writes the header data in the codestream and actualize ndata with the header length. The header is either a MainHeaderEncoder or a TileHeaderEncoder.

Specified by:

commitBitstreamHeader in class CodestreamWriter

Parameters:

he - The current header encoder.

Throws:

IOException - If an I/O error occurs while writing the data.

initSOP_EPHArrays

private void initSOP_EPHArrays()

Performs the initialisation of the arrays that are used to store the values used to write SOP and EPH markers