mediaframe.mpeg1
Class Huffmann

java.lang.Object
  |
  +--mediaframe.mpeg1.Huffmann

public class Huffmann

extends java.lang.Object

The Huffmann class represents VLC (Hufmann) decoder. It's data base are some arrays which logically constitute a binary tree.

Field Summary

static int[]	dct_coeff_len_tab1 The huffman tree (length part) for the DCT coefficients (huffman index 1...1024).
static int[]	dct_coeff_len_tab2 The huffman tree (length part) for the DCT coefficients (huffman index 1024..65535).
static int[]	dct_coeff_val_tab1 The huffman tree (value part) for the DCT coefficients (huffman index 1...1024).
static int[]	dct_coeff_val_tab2 The huffman tree (length part) for the DCT coefficients (huffman index 1024..65535).
static int	DCT_ESCAPE DCT_ESCAPE constanta (byte value) in a bit stream.
static int	EOB End of block constanta (byte value) in a bit stream.
private io_tool	mpeg_stream The input movie's data bit stream.
static Tables	tables The Huffman tables for decoding a bit stream.

Constructor Summary

(package private)

Huffmann(io_tool stream) Constructs a VLC (Hufmann) decoder and loads Huffman tables.

Method Summary

int[]	decode(int max_length, int[][] tab) The method "decode" is the VLC (Hufmann) decoder.
int	decodeCoeff() Decodes one AC coefficient from a bit stream.
static Tables	loadTables() Loads a Huffman tables from a resource file.

Methods inherited from class java.lang.Object

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

Field Detail

mpeg_stream

private io_tool mpeg_stream

The input movie's data bit stream.

tables

public static final Tables tables

The Huffman tables for decoding a bit stream.

DCT_ESCAPE

public static final int DCT_ESCAPE

DCT_ESCAPE constanta (byte value) in a bit stream.

See Also:

Constant Field Values

EOB

public static final int EOB

End of block constanta (byte value) in a bit stream.

See Also:

Constant Field Values

dct_coeff_val_tab1

public static int[] dct_coeff_val_tab1

The huffman tree (value part) for the DCT coefficients (huffman index 1...1024).

dct_coeff_val_tab2

public static int[] dct_coeff_val_tab2

The huffman tree (length part) for the DCT coefficients (huffman index 1024..65535).

dct_coeff_len_tab1

public static int[] dct_coeff_len_tab1

The huffman tree (length part) for the DCT coefficients (huffman index 1...1024).

dct_coeff_len_tab2

public static int[] dct_coeff_len_tab2

The huffman tree (length part) for the DCT coefficients (huffman index 1024..65535).

Constructor Detail

Huffmann

Huffmann(io_tool stream)

Constructs a VLC (Hufmann) decoder and loads Huffman tables.

Parameters:

stream - the input movie's data bit stream.

Method Detail

decode

public final int[] decode(int max_length,
                          int[][] tab)
                   throws java.lang.InterruptedException,
                          java.io.EOFException

The method "decode" is the VLC (Hufmann) decoder. It traverses the "tree" given as parameter till a NIL(-1) index occurs. It returns the decoded value(s). The return type is an array because some VLCs refer to more than 1 result.

Parameters:

max_length - maximum amount of bits that could be readed from a stream to decode values.

tab - the huffman table for decoding bit stream.

Returns:

the decoded value(s).

Throws:

java.lang.InterruptedException - raises if another process interrupts the current process.

EOFException - raises if the end of the file has been reached.

decodeCoeff

public final int decodeCoeff()
                      throws java.lang.InterruptedException,
                             java.io.EOFException

Decodes one AC coefficient from a bit stream.

Returns:

the decoded value.

Throws:

java.lang.InterruptedException - raises if another process interrupts the current process.

EOFException - raises if the end of the file has been reached.

loadTables

public static Tables loadTables()

Loads a Huffman tables from a resource file.

Returns:

the Huffman tables which has been loaded.