This gem isn't originally mine, but i've added things etc…
The gem can now be used with bundler and by extension, Rails 3, just use…
gem “mp4info”, :git => “git://github.com/arbarlow/ruby-mp4info.git”, :require => “mp4info”
MP4Info supports the reading of tags and file info from MP4 audio files. It is based on the Perl module MP4::Info (search.cpan.org/~jhar/MP4-Info/) Note: MP4Info does not currently support Unicode strings.
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
With mp4info.rb in your load path, do:
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