MP4Info

= Introduction MP4Info supports the reading of tags and file info from MP4 audio files. It is based on the Perl module MP4::Info (http://search.cpan.org/~jhar/MP4-Info/) Note: MP4Info does not currently support Unicode strings.

= License Copyright (c) 2004-2007 Jonathan Harris [e-mail] Copyright (C) 2006-2007 Jason Terk [e-mail]

This program is free software; you can redistribute it and/or modify it under the terms of version 2 of the GNU General Public License as published by the Free Software Foundation.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

= Usage

With mp4info.rb in your load path, do:

require 'mp4info'

Once the library is loaded, an MP4Info object is created by sending an IO object to MP4Info#new. MP4Info also provides the MP4Info#open method, which takes String containing a filename.

file = "my_favorite_song.mp4" info = MP4Info.open(file)

io_stream = File.new("that_other_song.m4a") other_info = MP4Info.new(io_stream)

Once an MP4Info object is succesfully created, a number of tags are avalible:

• ALB - Album
• APID - Apple Store ID
• ART - Artist
• CMT - Comment
• COVR - Album art (typically jpeg data)
• CPIL - Compilation (boolean)
• CPRT - Copyright statement
• DAY - Year
• DISK - Disk number & total (Array of two integers)
• GNRE - Genre
• GRP - Grouping
• NAM - Title
• RTNG - Rating (integer)
• TMPO - Tempo (integer)
• TOO - Encoder
• TRKN - Track number & total (Array of two integers)
• WRT - Author or composer

The following extra information about the audio file is also provided:

• VERSION - MPEG version (=4)

• LAYER - Doesn't really mean antyhing, but here in case we need it for compatibility with an MP3 library...

• BITRATE - Bitrate in kbps (average for VBR files) The formula used to generate this seems a little suspect.

• FREQUENCY - Frequency in kHz

• SIZE - Bytes in audio stream

• SECS - Total seconds, rounded to nearest second

• MM - Minutes

• SS - Leftover seconds

• MS - Leftover milliseconds, rounded to nearest millisecond

• TIME - Time in MM:SS, rounded to nearest second

• COPYRIGHT - Non-nil if audio is copyrighted

• ENCRYPTED - Non-nil if audio data is encrypted