This library is a wrapper for the ExifTool command-line application (http://www.sno.phy.queensu.ca/~phil/exiftool) written by Phil Harvey. It provides the full power of ExifTool to Ruby: reading and writing of EXIF-data, IPTC-data and XMP-data.
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 http://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 http://github.com/wilg/mini_exiftool_vendored or http://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
or simply add to the following to your Gemfile:
If you need to support older versions of Ruby or Exiftool (see Requirements above)
gem install --version "< 2.0.0" mini_exiftool
or if you use a Gemfile add:
gem 'mini_exiftool', '<2.0.0'
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 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
In general MiniExiftool is very intuitive to use as the following examples show:
# Reading meta data from a file photo = MiniExiftool.new 'photo.jpg' puts photo.title # Alternative reading meta data from an IO instance photo = MiniExiftool.new io 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.md. in the project root folder and have a look at the examples in directory examples.
The philosophy of MiniExiftool is safety over performance. It can not handle more than one file at once. Writing operations are executed on a copy of the original file to have atomic writing: Either all changed values are written or none. To be able to assign errors to a specific tag writing operations also call the Exiftool command-line application once for each changed tag!
In short: MiniExiftool has a very bad performance especially at write operations.
If you work with many files it is strongly recommended not to use MiniExiftool but instead my other gem MultiExiftool. This is designed to handle many files and do reading and writing fast.
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:
Internal character sets
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 (http://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
This problem you can solve with the option
# 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 github at https://github.com/janfri/mini_exiftool feel free to contribute!
Jan Friedrich firstname.lastname@example.org
Copyright / License
Copyright (c) 2007-2016 by Jan Friedrich
Licensed under terms of the GNU LESSER GENERAL PUBLIC LICENSE, Version 2.1, February 1999 (see file COPYING for more details)