This library is wrapper for the Exiftool command-line application (www.sno.phy.queensu.ca/~phil/exiftool) written by Phil Harvey. Read and write access is done in a clean OO manner.
Ruby 1.9 or higher and an installation of the Exiftool command-line application at least version 7.65. If you run on Ruby 1.8 or with a prior exiftool version install mini_exiftool version 1.x.x. Instructions for installation you can find under www.sno.phy.queensu.ca/~phil/exiftool/install.html .
Alternatively Wil Gieseler has bundled a meta-gem that eliminates the need for a separate Exiftool installation. Have a look at github.com/wilg/mini_exiftool_vendored or rubygems.org/gems/mini_exiftool_vendored .
First you need Exiftool (see under Requirements above). Then you can simply install the gem with
gem install mini_exiftool
If you need to support older versions of Ruby or exiftool (see Requirements above)
gem install --version "< 2.0.0" mini_exiftool
You can manually set the exiftool command that should be used via
MiniExiftool.command = '/path/to/my/exiftool'
In addition, you can also tell MiniExiftool where to store the PStore files with tags which exiftool supports. The PStore files are used for performance issues. Per default the PStore files are stored in a sub directory .mini_exiftool or _mini_exiftool under your home directory.
MiniExiftool.pstore_dir = '/path/to/pstore/dir'
If you’re using Rails, this is easily done with
MiniExiftool.pstore_dir = Rails.root.join('tmp').to_s
Important hint: if you have to change the configuration you have to do this direct after require ‘mini_exiftool’.
In general MiniExiftool is very intuitive to use as the following examples show:
# Reading meta data photo = MiniExiftool.new 'photo.jpg' puts photo.title # Writing meta data photo = MiniExiftool.new 'photo.jpg' photo.title = 'This is the new title' photo.save # Copying meta data photo = MiniExiftool.new('photo.jpg') photo.copy_tags_from('another_photo.jpg', :author)
For further information about using MiniExiftool read the Tutorial.rdoc in the project root folder and have a look at the examples in directory examples.
In MiniExiftool all strings are encoded in UTF-8. If you need other encodings in your project use the String#encod* methods.
If you have problems with corrupted strings when using MiniExiftool there are two reasons for this:
You can specify the charset in which the meta data is in the file encoded if you read or write to some sections of meta data (i.e. IPTC, XMP …). It exists various options of the form *_encoding: exif, iptc, xmp, png, id3, pdf, photoshop, quicktime, aiff, mie and vorbis.
For IPTC meta data it is recommended to set also the CodedCharacterSet tag.
Please read the section about the character sets of the ExifTool command line application carefully to understand what’s going on (www.sno.phy.queensu.ca/~phil/exiftool/faq.html#Q10)!
# Using UTF-8 as internal encoding for IPTC tags and MacRoman
# as internal encoding for EXIF tags
photo = MiniExiftool.new('photo.jpg', iptc_encoding: 'UTF8',
exif_encoding: 'MacRoman'
# IPTC CaptionAbstract is already UTF-8 encoded
puts photo.caption_abstract
# EXIF Comment is converted from MacRoman to UTF-8
puts photo.comment
photo = MiniExiftool.new('photo.jpg', iptc_encoding: 'UTF8',
exif_encoding: 'MacRoman'
# When saving IPTC data setting CodedCharacterSet as recommended
photo.coded_character_set = 'UTF8'
# IPTC CaptionAbstract will be stored in UTF-8 encoding
photo.caption_abstract = 'Some text with Ümläuts'
# EXIF Comment will be stored in MacRoman encoding
photo.comment = 'Comment with Ümläuts'
photo.save
You use the correct internal character set but in the string are still corrupt characters. This problem you can solve with the option replace_invalid_chars:
# Replace all invalid characters with a question mark photo = MiniExiftool.new('photo.jpg', replace_invalid_chars: '?')
The code is hosted in a git repository on Gitorious at gitorious.org/mini_exiftool and github at github.com/janfri/mini_exiftool feel free to contribute!
Jan Friedrich <[email protected]>
Copyright © 2007-2014 by Jan Friedrich
Licensed under terms of the GNU LESSER GENERAL PUBLIC LICENSE, Version 2.1, February 1999 (see file COPYING for more details)