Friday, April 30, 1999

***WARNING***

This module seems quite stable, and my tests (more extensive now)
seem to work well, and the reports I've gotten are positive.
There have been significant changes to the most important functions,
which should improve performance and reliability.  These should
make the module better, but may in some cases make it worse
for your MP3 files.

If you are having problems with an MP3 file and this module, please
contact me directly.  I will likely ask you to put the MP3 file(s)
in question in a place I can access them (HTTP or FTP), so I can test
them directly (NOTE: this is not just a clever ploy to get you to
send me MP3s :).

I don't anticipate serious problems, and in fact I have not been able
to find an MP3 file that the new module fails on.  But you have been
warned.

***WARNING***

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.

Check out the script from Meng Weng Wong in eg/, it's pretty cool, and
if you have the CDDB module, it will be even cooler.  There's
also a MacPerl script for editing tags (mp3tag) in there.

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

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.

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

   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
   (STEREO), MPEG layer (LAYER), BITRATE, and FREQUENCY.

TODO
   ID3v2 Support
       Added recognition of ID3v2 headers, speeding up `get_mp3info' for
       those files that have ID3v2 tags. Want to add functionality to get
       and set data in those tags. Too busy to do it. If someone wants to
       patch the module, feel free to submit patches.

   Variable Bitrate MP3s
       Get correct length in MM:SS ... anything other problems relating
       to this? Need algorithm for it.

HISTORY
   v0.63, Friday, April 30, 1999
       Added ID3v1.1 support. Thanks Trond Michelsen <[email protected]>,
       Pass F. B. Travis <[email protected]>.

       Added 255 (\xFF) as default genre. Thanks Andrew Phillips
       <[email protected]>.

       I think I fixed bug relating to spaces in ID3v2 headers. Thanks
       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. Thanks to Tom Brown <[email protected]> for his help.

       See for more info on ID3v2:

           http://www.id3.org/

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

   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
       <[email protected]>).

       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.

           mailto:[email protected]
           http://www.zevils.com/linux/mp3tools/

       Thanks also to Peter Kovacs <[email protected]>.

   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:

           mailto:[email protected]
           http://www.dv.co.yu/mp3list/mpgtools.htm
           http://www.dv.co.yu/mp3list/mpeghdr.htm

       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 <[email protected]>).

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

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.

   Thanks to Johann Lindvall for his mp3tool program:

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

   Helped me figure it all out.

VERSION
   v0.63, Friday, April 30, 1999

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

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