Introduction

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.

License

Copyright (C) 2006 Jason Terk <rain@xidus.net>

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

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