CADI.Common.LogicalTarget.JPEG2000.Decode
Class RawDecoder

java.lang.Object
  CADI.Common.LogicalTarget.JPEG2000.Decode.RawDecoder

All Implemented Interfaces:

Decoder

public class RawDecoder
extends java.lang.Object
implements Decoder

This class decodes bits from a compatible JPEG2000 codestream (without encoded with the MQ), i.e. when a byte 0xFF is found, the first bit of the following byte is skipped. This class could be used when encoding using the bypass mode of JPEG2000 or in other situations, for instance when decoding the packet headers. Usge example:
construct
decodeBit
decodeBit
swapInputByteStream
restart
decodeBit
decodeBit
...

Version:

1.0

Author:

Group on Interactive Coding of Images (GICI)

Field Summary

private boolean	foundFF Flag used to know if a byte with a value of 0xFF has been found.
private ByteStream	inputByteStream Bytestream from which the MQ decoder reads data.
private int	L Byte position to be read from the inputByteStream.
private int	t Number of bits to transfer (down counter).
private int	Tr Byte to transfer.

Constructor Summary

RawDecoder()
Constructor that does not initializes nothing.

RawDecoder(ByteStream inputByteStream)
Constructor that initializes the internal registers and outputByteStream.

Method Summary

boolean	decodeBit() Decode a bit.
boolean	decodeBit(int context) Decode a bit using some context.
void	reset() For compatibility.
void	restart() Fills the Tr register.
void	swapInputByteStream(ByteStream inputByteStream) Swaps the current inputByteStream.

Methods inherited from class java.lang.Object

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

Field Detail

inputByteStream

private ByteStream inputByteStream

Bytestream from which the MQ decoder reads data.

The content must be understood as a ByteStream.

t

private int t

Number of bits to transfer (down counter).

Usually it is initialized to 8, then count down until 0.

Tr

private int Tr

Byte to transfer.

Byte flushed to the outputByteStream.

L

private int L

Byte position to be read from the inputByteStream.

Only positive values allowed. The first byte is 0.

foundFF

private boolean foundFF

Flag used to know if a byte with a value of 0xFF has been found. In this case a new byte is readed from the bytestream although it does not be used.

True when a 0xFF byte is found.

Constructor Detail

RawDecoder

public RawDecoder()

Constructor that does not initializes nothing. Before to use this class you should call the swapInputByteStream function.

RawDecoder

public RawDecoder(ByteStream inputByteStream)
           throws ErrorException

Constructor that initializes the internal registers and outputByteStream.

Parameters:

inputByteStream - the input stream of bytes

Throws:

ErrorException - when end of ByteStream is reached

Method Detail

decodeBit

public boolean decodeBit()
                  throws ErrorException

Decode a bit.

Specified by:

decodeBit in interface Decoder

Returns:

a boolean indicating the bit decoded

Throws:

ErrorException - when end of ByteStream is reached

decodeBit

public boolean decodeBit(int context)
                  throws ErrorException

Decode a bit using some context. The context is not used (this function is only for compatibility).

Specified by:

decodeBit in interface Decoder

Parameters:

context - a byte that indicates the context of the decoded bit

Returns:

a boolean indicating the bit decoded

Throws:

ErrorException - when end of ByteStream is reached

swapInputByteStream

public void swapInputByteStream(ByteStream inputByteStream)

Swaps the current inputByteStream. After calling this function you should call the restart function.

Specified by:

swapInputByteStream in interface Decoder

Parameters:

inputByteStream - the input stream of bytes

restart

public void restart()
             throws ErrorException

Fills the Tr register. This function should be called every time a new ByteStream is passed to the decoder.

Specified by:

restart in interface Decoder

Throws:

ErrorException - for compatibility

reset

public void reset()

For compatibility.

Specified by:

reset in interface Decoder