Monday, July 12, 1999

Major update to this version is preliminary support for reading
ID3v2 tags.  It is only for ID3v2.3.0 (not ID3v2.2.0 or older).
Writing support will come eventually.  See docs for more details.

Included tests don't yet test ID3v2 support.

This archive can always be obtained from:

   http://www.perl.com/CPAN/authors/id/CNANDOR/
   http://www.perl.com/CPAN/modules/by-module/MPEG/

Mac users: The file is a tarred, gzipped file.  Use Stuffit Expander
or a similar program (like my cpan-mac stuff, also in the CNANDOR
directory) to get at the archive.

Please let me know how well it does(n't) work, and any changes you'd
like to see.

#============================================================================

NAME
   MPEG::MP3Info - Manipulate / fetch info from MP3 audio files

SYNOPSIS
       #!perl -w
       use MPEG::MP3Info;
       my $file = 'Pearls_Before_Swine.mp3';
       set_mp3tag($file, 'Pearls Before Swine', q"77's",
         'Sticks and Stones', '1990', q"(c) 1990 77's LTD.", 'rock & roll');

       my $tag = get_mp3tag($file) or die "No TAG info";
       $tag->{GENRE} = 'rock';
       set_mp3tag($file, $tag);

       my $info = get_mp3info($file);
       printf "$file length is %d:%d", $info->{MM}, $info->{SS};

DESCRIPTION
   use_winamp_genres()
       Puts WinAmp genres into `@mp3_genres' and `%mp3_genres'.

       You can import the data structures with one of:

           use MPEG::MP3Info qw(:genres);
           use MPEG::MP3Info qw(:DEFAULT :genres);
           use MPEG::MP3Info qw(:all);

   remove_mp3tag (FILE)
       Removes last 128 bytes from file if those last 128 bytes begin
       with the text `TAG'. File will be 128 bytes shorter. Returns undef
       if no existing TAG found, 1 on successful removal of TAG.

   set_mp3tag (FILE, TITLE, ARTIST, ALBUM, YEAR, COMMENT, GENRE [, TRACKNUM])
   set_mp3tag (FILE, $HASHREF)
       Adds/changes tag information in an MP3 audio file. Will clobber
       any existing information in file.

       Fields are TITLE, ARTIST, ALBUM, YEAR, COMMENT, GENRE. All fields
       have a 30-byte limit, except for YEAR, which has a four-byte
       limit, and GENRE, which is one byte in the file. The GENRE passed
       in the function is a case-insensitive text string representing a
       genre found in `@mp3_genres'.

       Will accept either a list of values, or a hashref of the type
       returned by `get_mp3tag'.

       If TRACKNUM is present (for ID3v1.1), then the COMMENT field can
       only be 28 bytes.

       ID3v2 support will come eventually.

   get_mp3tag (FILE [, VERSION, RAW_V2])
       Returns hash reference containing tag information in MP3 file.
       Same info as described in `set_mp3tag'.

       If VERSION is `1', the information is taken from the ID3v1 tag (if
       present). If VERSION is `2', the information is taken from the
       ID3v2 tag (if present). If VERSION is not supplied, the ID3v1 tag
       is read if present, and then, if present, the ID3v2 tag
       information will override any existing ID3v1 tag info.

       If the ID3v2 version is older than ID3v2.3.0, it will not be read
       (and a warning will be issued if -w is on).

       If RAW_V2 is false or not supplied and VERSION is `2', only the
       tags corresponding to ID3v1 tags are returned, with the same keys
       in the returned hashref.

       If RAW_V2 is true and VERSION is `2', `get_mp3tag' will return a
       hash of tag four-character IDs and their data. Tag IDs and their
       meanings are in the global hash (not exported) `%v2_tag_names'.

           my $tag = get_mp3tag('mysong.mp3', 2, 1);   # ID3v2, raw ID3v2 tags
           for (keys %$tag) {
               printf "%s => %s\n", $MPEG::MP3Info::v2_tag_names{$_}, $tag->{$_};
           }

   get_mp3info (FILE)
       Returns hash reference containing file information for MP3 file.
       This data cannot be changed. Returned data includes MP3 version
       (VERSION), total time in minutes (MM) and seconds (SS), boolean
       for STEREO, MPEG layer (LAYER), BITRATE, MODE, boolean for
       COPYRIGHT, and FREQUENCY.

       Variable bitrates not yet supported. See the section on "TODO".

TROUBLESHOOTING
   If you find a bug, please send me a patch. If you cannot figure out
   why it does not work for you, please put the MP3 file in a place where
   I can get it (preferably via FTP) and send me mail regarding where I
   can get the file, with a detailed description of the problem.

   If I download the file, after debugging the problem I will not keep
   the MP3 file if it is not legal for me to have it. Just let me know if
   it is legal for me ot keep it or not.

TODO
   ID3v2 Support
       First go at adding support for reading ID3v2 tags. Still need to
       do more, such as using Compress::Zlib to decompress compressed
       tags. But until I see this in use, I won't bother. I might not be
       able to support Unicode at all, until Perl supports 16-bit
       Unicode. If something does not work properly with reading, follow
       the instructions above for troubleshooting.

       Still need to add support for writing ID3v2 tags, and work on API
       a bit.

   Variable Bitrate MP3s
       Get correct length in MM:SS ... anything other problems relating
       to this? Need algorithm for it. If someone supplies it, I'd be
       happy to implement it.

HISTORY
   v0.71, Thursday, July 8, 1999
       Several fixes to ID3v2 support unpack unsigned instead of signed,
       don't bail out after 4096-byte offsets on long ID3v2 headers.
       Thanks much to Matthew Sachs.

   v0.70, Saturday, July 3, 1999
       Added preliminary ID3v2 reading support in `get_mp3tag'. Thanks
       much to Tom Brown.

   v0.64, Thursday, July 1, 1999
       Found bug in checking TRACKNUM parameter, used \d instead of \d+.
       Only gives spurious warnings, doesn't affect anything else.

       Cleaned up a bit, prepare for impending ID3v2 support.

       NOTE: truncate() broken in some builds of ActivePerl (517, maybe
       others). No changes to module to fix problem. (Brian Goodwin)

   v0.63, Friday, April 30, 1999
       Added ID3v1.1 support. (Trond Michelsen, Pass F. B. Travis)

       Added 255 (\xFF) as default genre. (Andrew Phillips)

       I think I fixed bug relating to spaces in ID3v2 headers. (Tom
       Brown)

   v0.62, Sunday, March 7, 1999
       Doc updates.

       Fix small unnoticable bug where ID3v2 offset is tag size plus 10,
       not just tag size.

       Not publickly released.

   v0.61, Monday, March 1, 1999
       Fixed problem of not removing nulls on return from `get_mp3tag'
       (was using spaces for padding before ... now trailing whitespace
       and all nulls are removed before returning tag info).

       Made tests more extensive (more for my own sanity when making all
       these changes than to make sure it works on other platforms and
       machines :).

   v0.60, Sunday, February 28, 1999
       Cleaned up a lot of stuff, added more comments, made `get_mp3info'
       much faster and much more reliable, and added recognition of ID3v2
       headers. (Tom Brown)

   v0.52, Sunday, February 21, 1999
       Fixed problem in `get_mp3tag' that changed value of `$_' in caller
       (Todd Hanneken).

   v0.51, Saturday, February 20, 1999
       Fixed problem with `%winamp_genres' having the wrong numbers
       (Matthew Sachs).

   v0.50, Friday, February 19, 1999
       Added `remove_mp3tag'. Addeed VERSION to the hash returned by
       `get_mp3info', and fixed a bug where STEREO was not being set
       correctly.

       Export all genre data structures on request. Added
       `use_winamp_genres' to use WinAmp genres. (Roland Steinbach)

       Added a `$MPEG::MP3Info::try_harder' variable that will try harder
       to find the MP3 header in a file. False by default. Can take a
       long time to fail, but should find most headers at any offets if
       set to true.

       Thanks to Matthew Sachs for his input and fixes, and for mp3tools.

   v0.20, Saturday, October 17, 1998
       Changed name from `MPEG::MP3Tag' to `MPEG::MP3Info', because it
       does more than just TAG stuff now.

       Made header stuff even more reliable. Lots of help and testing
       from Meng Weng Wong again. :-)

   v0.13, Thursday, October 8, 1998
       Had some problems with header verification, got some code from
       Predrag Supurovic with his mpgtools. Great stuff. Also did some
       looping to find a header if it is not in the "right" place. I did
       what I think it is a smart way to do it, since some files have the
       header as far down as 2 kbytes into the file. First, I look at
       position 0, then at position 36 (a position where I have found
       many headers), then I start at 0 again and jump in 128-byte
       chunks. Once I do that a bunch of times, I go back at the
       beginning and try at 0 and go ahead in 1-byte chunks for a bunch
       more times.

       If you have an MP3 that has the header begin at an odd place like
       byte 761, then I suggest you strip out the junk before the header
       begins. :-)

   v0.12, Friday, October 2, 1998
       Added `get_mp3info'. Thanks again to mp3tool source from Johann
       Lindvall, because I basically stole it straight (after converting
       it from C to Perl, of course).

       I did everything I could to find the header info, but if anyone
       has valid MP3 files that are not recognized, or has suggestions
       for improvement of the algorithms, let me know.

   v0.04, Tuesday, September 29, 1998
       Changed a few things, replaced a regex with an `unpack'. (Meng
       Weng Wong)

   v0.03, Tuesday, September 8, 1998
       First public release.

THANKS
   Johann Lindvall, Meng Weng Wong <[email protected]>, Predrag
   Supurovic <[email protected]>, Matthew Sachs <[email protected]>,
   Peter Kovacs <[email protected]>, Roland Steinbach <roland@support-
   system.com>, Todd Hanneken <[email protected]>, Tom Brown
   <[email protected]>, Andrew Phillips <[email protected]>, Trond Michelsen
   <[email protected]>, Pass F. B. Travis <[email protected]>,
   Vittorio Bertola <[email protected]>, Brian Goodwin
   <[email protected]>.

AUTHOR AND COPYRIGHT
   Chris Nandor <[email protected]>, http://pudge.net/

   Copyright (c) 1999 Chris Nandor. 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.

SEE ALSO
   mp3tools
           http://www.zevils.com/linux/mp3tools/

   mpgtools
           http://www.dv.co.yu/mp3list/mpgtools.htm
           http://www.dv.co.yu/mp3list/mpeghdr.htm

   mp3tool
           http://www.dtek.chalmers.se/~d2linjo/mp3/mp3tool.html

   ID3v2
           http://www.id3.org/

VERSION
   v0.71, Saturday, July 3, 1999

#============================================================================

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