Ilya Zakharevich > MP3-Tag-0.92 > MP3::Tag::ID3v2

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Module Version: 0.91   Source   Latest Release: MP3-Tag-0.9714

NAME ^

MP3::Tag::ID3v2 - Read / Write ID3v2.x.y tags from mp3 audio files

SYNOPSIS ^

MP3::Tag::ID3v2 supports * Reading of ID3v2.2.0 and ID3v2.3.0 tags * Writing of ID3v2.3.0 tags

MP3::Tag::ID3v2 is designed to be called from the MP3::Tag module.

  use MP3::Tag;
  $mp3 = MP3::Tag->new($filename);

  # read an existing tag
  $mp3->get_tags();
  $id3v2 = $mp3->{ID3v2} if exists $mp3->{ID3v2};

  # or create a new tag
  $id3v2 = $mp3->new_tag("ID3v2");

See MP3::Tag for information on the above used functions.

* Reading a tag

  $frameIDs_hash = $id3v2->get_frame_ids('truename');

  foreach my $frame (keys %$frameIDs_hash) {
      my ($name, @info) = $id3v2->get_frame($frame);
      for my $info (@info) {  
          if (ref $info) {
              print "$name ($frame):\n";
              while(my ($key,$val)=each %$info) {
                  print " * $key => $val\n";
             }
          } else {
              print "$name: $info\n";
          }
      }
  }

* Adding / Changing / Removing / Writing a tag

  $id3v2->add_frame("TIT2", "Title of the song");
  $id3v2->change_frame("TALB","Greatest Album");
  $id3v2->remove_frame("TLAN");
  $id3v2->write_tag();

* Removing the whole tag

  $id3v2->remove_tag();

* Get information about supported frames

  %tags = $id3v2->supported_frames();
  while (($fname, $longname) = each %tags) {
      print "$fname $longname: ", 
            join(", ", @{$id3v2->what_data($fname)}), "\n";
  }

AUTHOR ^

Thomas Geffert, thg@users.sourceforge.net

DESCRIPTION ^

get_frame_ids()

  $frameIDs = $tag->get_frame_ids;
  $frameIDs = $tag->get_frame_ids('truename');

  [old name: getFrameIDs() . The old name is still available, but you should use the new name]

get_frame_ids loops through all frames, which exist in the tag. It returns a hash reference with a list of all available Frame IDs. The keys of the returned hash are 4-character-codes (short names), the internal names of the frames, the according value is the english (long) name of the frame.

You can use this list to iterate over all frames to get their data, or to check if a specific frame is included in the tag.

If there are multiple occurences of a frame in one tag, the first frame is returned with its normal short name, following frames of this type get a '00', '01', '02', ... appended to this name. These names can then used with get_frame to get the information of these frames. These fake frames are not returned if 'truename' argument is set; one can still use get_frames() to extract the info for all of the frames with the given short name.

get_frame()

  ($info, $name, @rest) = $tag->get_frame($ID);
  ($info, $name, @rest) = $tag->get_frame($ID, 'raw');

  [old name: getFrame() . The old name is still available, but you should use the new name]

get_frame gets the contents of a specific frame, which must be specified by the 4-character-ID (aka short name). You can use get_frame_ids to get the IDs of the tag, or use IDs which you hope to find in the tag. If the ID is not found, get_frame returns empty list, so $info and $name become undefined.

Otherwise it extracts the contents of the frame. Frames in ID3v2 tags can be very small, or complex and huge. That is the reason, that get_frame returns the frame data in two ways, depending on the tag.

If it is a simple tag, with only one piece of data, this date is returned directly as ($info, $name), where $info is the text string, and $name is the long (english) name of the frame.

If the frame consist of different pieces of data, $info is a hash reference, $name is again the long name of the frame.

The hash, to which $info points, contains key/value pairs, where the key is always the name of the data, and the value is the data itself.

If the name starts with a underscore (as eg '_code'), the data is probably binary data and not printable. If the name starts without an underscore, it should be a text string and printable.

If the second parameter 'raw' is given, the whole frame data is returned, but not the frame header. If the second parameter is 'intact', no mangling of embedded "\0" and trailing spaces is performed.

If the data was stored compressed, it is uncompressed before it is returned (even in raw mode). Then $info contains a string with all data (which might be binary), and $name the long frame name.

See also MP3::Tag::ID3v2-Data for a list of all supported frames, and some other explanations of the returned data structure.

If more than one frame with name $ID is present, @rest contains $info fields for all consequent frames with the same name.

! Encrypted frames are not supported yet !

! Some frames are not supported yet, but the most common ones are supported !

get_frame_option()

  $options = get_frame_option($ID);

  Option is a hash reference, the hash contains all possible options.
  The value for each option is 0 or 1.

  groupid    -- not supported yet
  encryption -- not supported yet
  compression -- Compresses frame before writing tag; 
                 compression/uncompression is done automatically
  read_only   -- Ignored by this library, should be obeyed by application
  file_preserv -- Ignored by this library, should be obeyed by application
  tag_preserv -- Ignored by this library, should be obeyed by application

set_frame_option()

  $options = set_frame_option($ID, $option, $value);

  Set $option to $value (0 or 1). If successfull the new set of
  options is returned, undef otherwise.

  groupid    -- not supported yet
  encryption -- not supported yet
  compression -- Compresses frame before writing tag; 
                 compression/uncompression is done automatically
  read_only   -- Ignored by this library, should be obeyed by application
  file_preserv -- Ignored by this library, should be obeyed by application
  tag_preserv -- Ignored by this library, should be obeyed by application

get_frames()

  ($name, @info) = get_frames($ID);
  ($name, @info) = get_frames($ID, 'raw');

Same as get_frame() with different order of the returned values. $name and elements of the array @info have the same semantic as for get_frame(); each frame with id $ID produces one elements of array @info.

write_tag()

  $id3v2->write_tag($ignore_error);

Saves all frames to the file. It tries to update the file in place, when the space of the old tag is big enough for the new tag. Otherwise it creates a temp file with a new tag (i.e. copies the whole mp3 file) and renames/moves it to the original file name.

An extended header with CRC checksum is not supported yet.

Encryption of frames and group ids are not supported. If $ignore_error is set, these options are ignored and the frames are saved without these options. If $ignore_error is not set and a tag with an unsupported option should be save, the tag is not written and a 0 is returned.

If a tag with an encrypted frame is read, and the frame is not changed it can be saved encrypted again.

ID3v2.2 tags are converted automatically to ID3v2.3 tags during writing. If a frame cannot be converted automatically (PIC; CMR), writing aborts and returns a 0. If $ignore_error is true, only not convertable frames are ignored and not written, but the rest of the tag is saved as ID3v2.3.

At the moment the tag is automatically unsynchronized.

If the tag is written successfully, 1 is returned.

remove_tag()

  $id3v2->remove_tag();

Removes the whole tag from the file by copying the whole mp3-file to a temp-file and renaming/moving that to the original filename.

Do not use remove_tag() if you only want to change a header, as otherwise the file is copied unneccessary. Use write_tag() directly, which will override an old tag.

add_frame()

  $fn = $id3v2->add_frame($fname, @data);

Add a new frame, identified by the short name $fname. The $data must consist from so much elements, as described in the ID3v2.3 standard. If there is need to give an encoding parameter and you would like standard ascii encoding, you can omit the parameter or set it to 0. Any other encoding is not supported yet, and thus ignored.

It returns the the short name $fn, which can differ from $fname, when there existed already such a frame. If no other frame of this kind is allowed, an empty string is returned. Otherwise the name of the newly created frame is returned (which can have a 01 or 02 or ... appended).

@data must be undef or the number of elements of @data must be equal to the number of fields of the tag. See also MP3::Tag::ID3v2-Data.

You have to call write_tag() to save the changes to the file.

Examples:

 $f = add_frame("TIT2", 0, "Abba");   # $f="TIT2"
 $f = add_frame("TIT2", "Abba");      # $f="TIT201", encoding=0 implicit

 $f = add_frame("COMM", "ENG", "Short text", "This is a comment");

 $f = add_frame("COMM");              # creates an empty frame

 $f = add_frame("COMM", "ENG");       # ! wrong ! $f=undef, becaues number 
                                      # of arguments is wrong

change_frame()

  $id3v2->change_frame($fname, @data);

Change an existing frame, which is identified by its short name $fname. @data must be same as in add_frame;

If the frame $fname does not exist, undef is returned.

You have to call write_tag() to save the changes to the file.

remove_frame()

  $id3v2->remove_frame($fname);

Remove an existing frame. $fname is the short name of a frame, eg as returned by get_frame_ids.

You have to call write_tag() to save the changes to the file.

supported_frames()

  $frames = $id3v2->supported_frames();

Returns a hash reference with all supported frames. The keys of the hash are the short names of the supported frames, the according values are the long (english) names of the frames.

what_data()

  ($data, $res_inp) = $id3v2->what_data($fname);

Returns an array reference with the needed data fields for a given frame. At this moment only the internal field names are returned, without any additional information about the data format of this field. Names beginning with an underscore (normally '_data') can contain binary data.

$resp_inp is a reference to an array, which contains information about a restriction for the content of the data field ( coresspodending to the same array field in the @$data array). If the entry is undef, no restriction exists. Otherwise it is a hash. The keys of the hash are the allowed input, the correspodending value is the value which should stored later in that field. If the value is undef then the key itself is valid for saving. If the hash contains an entry with "_FREE", the hash contains only suggestions for the input, but other input is also allowed.

Example for picture types of the APIC frame:

{"Other" = "\x00", "32x32 pixels 'file icon' (PNG only)" => "\x01", "Other file icon" => "\x02", ...}>

title( [@new_title] )

Returns the title composed of the tags configured via MP3::Tag-config('v2title')> call (with default 'Title/Songname/Content description' (TIT2)) from the tag. (For backward compatibility may be called by deprecated name song() as well.)

Sets TIT2 frame if given the optional arguments @new_title. If this is an empty string, the frame is removed.

_comment([$language])

Returns the file comment (COMM with an empty 'short') from the tag, or "Subtitle/Description refinement" (TIT3) frame (unless it is considered a part of the title).

comment()

   $val = $id3v2->comment();
   $newframe = $id3v2->comment('Just a comment for freddy', 'eng', 'personal');

Returns the file comment (COMM frame with an empty 'short' field) from the tag, or "Subtitle/Description refinement" (TIT3) frame (unless it is considered a part of the title).

If optional arguments ($comment, $short, $language) are present, sets the comment frame. If $language is omited, sets XXX (it should be lowercase 3-letter abbreviation according to ISO-639-2); if $short is omited, sets to ''. If $comment is an empty string, the frame is removed.

year( [@new_year] )

Returns the year (TYER/TDRC) from the tag.

Sets TYER and TDRC frames if given the optional arguments @new_year. If this is an empty string, the frame is removed.

The format is similar to timestamps of IDv2.4.0, but ranges can be separated by - or --, and non-contiguous dates are separated by , (comma). If periods need to be specified via duration, then one needs to use the ISO 8601 /-notation (e.g., see

  http://www.mcs.vuw.ac.nz/technical/software/SGML/doc/iso8601/ISO8601.html

); the duration/end_timestamp is not supported.

On output, ranges of timestamps are converted to - or -- separated format depending on whether the timestamps are years, or have additional fields.

If configuration variable year_is_timestamp is false, the return value is always the year only (of the first timestamp of a composite timestamp).

Recall that ID3v2.4.0 timestamp has format yyyy-MM-ddTHH:mm:ss (year, "-", month, "-", day, "T", hour (out of 24), ":", minutes, ":", seconds), but the precision may be reduced by removing as many time indicators as wanted. Hence valid timestamps are yyyy, yyyy-MM, yyyy-MM-dd, yyyy-MM-ddTHH, yyyy-MM-ddTHH:mm and yyyy-MM-ddTHH:mm:ss. All time stamps are UTC. For durations, use the slash character as described in 8601, and for multiple noncontiguous dates, use multiple strings, if allowed by the frame definition.

track( [$new_track] )

Returns the track number (TRCK) from the tag.

Sets TRCK frame if given the optional arguments @new_track. If this is an empty string or 0, the frame is removed.

artist( [ $new_artist ] )

Returns the artist name (TPE1 (or TPE2 if TPE1 does not exist, of TCOM if neither TPE1 nor TPE2 exist)) from the tag.

Sets TPE1 frame if given the optional arguments @new_artist. If this is an empty string, the frame is removed.

album( [ $new_album ] )

Returns the album name (TALB) from the tag. If none is found, returns the "Content group description" (TIT1) frame (unless it is considered a part of the title).

Sets TALB frame if given the optional arguments @new_album. If this is an empty string, the frame is removed.

genre( [ $new_genre ] )

Returns the genre string from TCON frame of the tag.

Sets TCON frame if given the optional arguments @new_genre. If this is an empty string, the frame is removed.

version()

  $version = $id3v2->version();
  ($major, $revision) = $id3v2->version();

Returns the version of the ID3v2 tag. It returns a formatted string like "3.0" or an array containing the major part (eg. 3) and revision part (eg. 0) of the version number.

new()

  $tag = new($mp3fileobj);

new() needs as parameter a mp3fileobj, as created by MP3::Tag::File. new tries to find a ID3v2 tag in the mp3fileobj. If it does not find a tag it returns undef. Otherwise it reads the tag header, as well as an extended header, if available. It reads the rest of the tag in a buffer, does unsynchronizing if neccessary, and returns a ID3v2-object. At this moment only ID3v2.3 is supported. Any extended header with CRC data is ignored, so no CRC check is done at the moment. The ID3v2-object can be used to extract information from the tag.

Please use

   $mp3 = MP3::Tag->new($filename);
   $mp3->get_tags();                 ## to find an existing tag, or
   $id3v2 = $mp3->new_tag("ID3v2");  ## to create a new tag

instead of using this function directly

SEE ALSO ^

MP3::Tag, MP3::Tag::ID3v1, MP3::Tag::ID3v2-Data

ID3v2 standard - http://www.id3.org

COPYRIGHT ^

Copyright (c) 2000-2004 Thomas Geffert. All rights reserved.

This program is free software; you can redistribute it and/or modify it under the terms of the Artistic License, distributed with Perl.

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