Monday, March 6, 2000

Major update to this version is variable bitrate (VBR) support
and a name change; it is now MP3::Info.  A wrapper module is included
so scripts calling MPEG::MP3Info will still work.

Included tests don't yet test ID3v2 or VBR 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.   Thanks to all of the people who have sent me feedback
and ideas.  If something you want still remains unimplemented, let me
know.

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

NAME
    MP3::Info - Manipulate / fetch info from MP3 audio files

SYNOPSIS
            #!perl -w
            use MP3::Info;
            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 MP3::Info qw(:genres);
                use MP3::Info qw(:DEFAULT :genres);
                use MP3::Info 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", $MP3::Info::v2_tag_names{$_}, $tag->{$_};
                }

    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 more, 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.

HISTORY
    v0.80, Monday, March 6, 2000
        Better stripping of bad data (after nulls) in ID3 tags (Dave
        O'Neill)

        Fixed VERSION in get_mp3info to properly return 2 when
        appropriate. (Bogdan Surdu)

        Added VBR support. Average bitrate is returned as BITRATE, and
        minutes and seconds (MM and SS) should be accurate. (Andy Waite
        for pointer to MP3Ext)

        Made time calculation better overall.

        Made MP3 header validation routines more comprehensive. (Matthew
        Sachs for pointer to xmms source)

        Changed name to MP3::Info (with wrapper still named MP3::Info).

    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 `$MPEG::MP3Info::try_harder' (`$MP3::Info::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 offsets 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 <mengwong@pobox.com>, Predrag
    Supurovic <mpgtools@dv.co.yu>, Matthew Sachs <matthewg@zevils.com>,
    Peter Kovacs <kovacsp@egr.uri.edu>, Roland Steinbach <roland@support-
    system.com>, Todd Hanneken <thanneken@hds.harvard.edu>, Tom Brown
    <thecap@usa.net>, Andrew Phillips <asp@wasteland.org>, Trond Michelsen
    <mike@crusaders.no>, Pass F. B. Travis <pftravis@bellsouth.net>,
    Vittorio Bertola <v.bertola@vitaminic.com>, Brian Goodwin
    <brian@fuddmain.com>, Bogdan Surdu <tim@go.ro>, Andy Waite
    <andy@mailroute.com>, Chris Sidi <sidi@angband.org>, Luke Drumm
    <lukedrumm@mypad.com>, Dave O'Neill <dave@nexus.carleton.ca>, Edward
    Allen <allenej@c51844-a.spokn1.wa.home.com>.

AUTHOR AND COPYRIGHT
    Chris Nandor <pudge@pobox.com>, http://pudge.net/

    Copyright (c) 2000 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/

    Xing Variable Bitrate
                http://www.xingtech.com/support/partner_developer/mp3/vbr_sdk/

    MP3Ext
                http://rupert.informatik.uni-stuttgart.de/~mutschml/MP3ext/

    Xmms
                http://www.xmms.org/

VERSION
    v0.80, Monday, March 6, 2000

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