org.farng.mp3.id3
Class ID3v2_2Frame

java.lang.Object
  org.farng.mp3.AbstractMP3FileItem
      org.farng.mp3.AbstractMP3Fragment
          org.farng.mp3.id3.AbstractID3v2Frame
              org.farng.mp3.id3.ID3v2_2Frame

All Implemented Interfaces:

MP3MetadataItem

Direct Known Subclasses:

ID3v2_3Frame

public class ID3v2_2Frame
extends AbstractID3v2Frame

The headers of the frames are similar in their construction. They consist of one three character identifier (capital A-Z and 0-9) and one three byte size field, making a total of six bytes. The header is excluded from the size. Identifiers beginning with "X", "Y" and "Z" are for experimental use and free for everyone to use. Have in mind that someone else might have used the same identifier as you. All other identifiers are either used or reserved for future use. This gives us 46656 combinations of frame identifiers.

The three character frame identifier is followed by a three byte size descriptor, making a total header size of six bytes in every frame. The size is calculated as framesize excluding frame identifier and size descriptor (frame size - 6).

The decision to have a 6 byte frame header was taken in an attempt to balance big frames against little overhead. One might think that it's stupid to optimize away a few bytes when the entire MP3-file is soo huge. On the other hand I thought it was really cool that most ID3v1 tags, when converted to ID3v2 was smaller than before. Size does matter.

There is no fixed order of the frames' appearance in the tag, although it is desired that the frames are arranged in order of significance concerning the recognition of the file. The reason for this is to make it faster to search for a specific file by scanning the ID3v2 tags; an intelligent parser wouldn't have to keep reading the entire tag after having found that the file isn't the one being looked for. An example of such order: UFI, MCI, TT2 ...

A tag must contain at least one frame. A frame must be at least 1 byte big, excluding the 6-byte header.

If nothing else is said, a string is represented as ISO-8859-1 characters in the range $20 - $FF. All unicode strings use 16-bit unicode 2.0 (ISO/IEC 10646-1:1993, UCS-2). All numeric strings are always encoded as ISO-8859-1. Terminated strings are terminated with $00 if encoded with ISO-8859-1 and $00 00 if encoded as unicode. If nothing else is said, newline characters are forbidden. In ISO-8859-1, a new line is represented, when allowed, with $0A only. Frames that allow different types of text encoding have a text encoding description byte directly after the frame size. If ISO-8859-1 is used this byte should be $00, if unicode is used it should be $01.

The three byte language field is used to describe the language of the frame's content, according to ISO-639-2.
ISO-639-1 is not used since its supported languages are just a subset of those in ISO-639-2.

All URLs may be relative, e.g. "picture.png", "../doc.txt".

If a frame is longer than it should be, e.g. having more fields than specified in this document, that indicates that additions to the frame have been made in a later version of the ID3 standard. This is reflected by the revision number in the header of the tag.
This allows us to fix our mistakes as well as introducing new features in the already existing frames.

Version:

$Revision: 3 $

Author:

Eric Farng

Constructor Summary

ID3v2_2Frame()
Creates a new ID3v2_2Frame object.

ID3v2_2Frame(AbstractID3v2Frame frame)
Creates a new ID3v2_3Frame object.

ID3v2_2Frame(AbstractID3v2FrameBody body)
Creates a new ID3v2_2Frame object.

ID3v2_2Frame(ID3v2_2Frame frame)
Creates a new ID3v2_2Frame object.

ID3v2_2Frame(java.io.RandomAccessFile file)
Creates a new ID3v2_2Frame object.

Method Summary

int	getSize() Get the size of the item, in bytes.
void	read(java.io.RandomAccessFile file) import java.io.IOException; import java.io.RandomAccessFile; read from current file pointer position.
void	write(java.io.RandomAccessFile file) Method to write this object to the file argument at is current file pointer position.

Methods inherited from class org.farng.mp3.id3.AbstractID3v2Frame

getIdentifier, isValidID3v2FrameIdentifier, readBody, toString

Methods inherited from class org.farng.mp3.AbstractMP3Fragment

equals, getBody, isSubsetOf, setBody

Methods inherited from class java.lang.Object

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

Constructor Detail

ID3v2_2Frame

public ID3v2_2Frame()

Creates a new ID3v2_2Frame object.

ID3v2_2Frame

public ID3v2_2Frame(AbstractID3v2FrameBody body)

Creates a new ID3v2_2Frame object.

ID3v2_2Frame

public ID3v2_2Frame(ID3v2_2Frame frame)

Creates a new ID3v2_2Frame object.

ID3v2_2Frame

public ID3v2_2Frame(AbstractID3v2Frame frame)

Creates a new ID3v2_3Frame object.

ID3v2_2Frame

public ID3v2_2Frame(java.io.RandomAccessFile file)
             throws java.io.IOException,
                    InvalidTagException

Creates a new ID3v2_2Frame object.

Throws:

java.io.IOException

InvalidTagException

Method Detail

getSize

public int getSize()

Description copied from interface: MP3MetadataItem

Get the size of the item, in bytes.

Specified by:

getSize in interface MP3MetadataItem

Specified by:

getSize in class AbstractMP3FileItem

Returns:

size

read

public void read(java.io.RandomAccessFile file)
          throws java.io.IOException,
                 InvalidTagException

Description copied from class: AbstractMP3FileItem

import java.io.IOException; import java.io.RandomAccessFile; read from current file pointer position.

Specified by:

read in class AbstractMP3FileItem

Parameters:

file - file to read from

Throws:

java.io.IOException - on any I/O error

InvalidTagException

write

public void write(java.io.RandomAccessFile file)
           throws java.io.IOException

Description copied from class: AbstractMP3FileItem

Method to write this object to the file argument at is current file pointer position.

Specified by:

write in class AbstractMP3FileItem

Parameters:

file - file to write to

Throws:

java.io.IOException - on any I/O error