MultiExiftool

Description

This library is a wrapper for the ExifTool command-line application (https://exiftool.org) written by Phil Harvey. It is designed for dealing with multiple files at once by creating commands to call exiftool with various arguments, call it and parsing the results.

Examples

Reading

require 'multi_exiftool'

# Object oriented approach
reader = MultiExiftool::Reader.new
reader.filenames = Dir['*.jpg']
results = reader.read
unless reader.errors.empty?
  $stderr.puts reader.errors
end
results.each do |values|
  puts "#{values.file_name}: #{values.comment}"
end

# Functional approach
results, errors = MultiExiftool.read(Dir['*.jpg'])
unless errors.empty?
  $stderr.puts reader.errors
end
results.each do |values|
  puts "#{values.file_name}: #{values.comment}"
end

Writing

require 'multi_exiftool'

# Object oriented approach
writer = MultiExiftool::Writer.new
writer.filenames = Dir['*.jpg']
writer.values = {creator: 'Jan Friedrich', copyright: 'Public Domain'}
if writer.write
  puts 'ok'
else
  puts writer.errors
end

# Functional approach
errors = MultiExiftool.write(Dir['*.jpg'],  {creator: 'Jan Friedrich', copyright: 'Public Domain'})
if errors.empty?
  puts 'ok'
else
  puts writer.errors
end

If it is necessary to write different values to multiple files there is batch processing

require 'multi_exiftool'

# Object oriented approach

batch = MultiExiftool::Batch.new
Dir['*.jpg'].each_with_index do |filename, i|
  values = {creator: 'Jan Friedrich', copyright: 'Public Domain', comment: "This is file number #{i+1}."}
  batch.write filename, values
end
if batch.execute
  puts 'ok'
else
  puts batch.errors
end

# Functional approach

errors = MultiExiftool.batch do
  Dir['*.jpg'].each_with_index do |filename, i|
    values = {creator: 'Jan Friedrich', copyright: 'Public Domain', comment: "This is file number #{i+1}."}
    write filename, values
  end
end
if errors.empty?
  puts 'ok'
else
  puts errors
end

# or alternative with block parameter as yielded Batch instance

errors = MultiExiftool.batch do |batch|
  Dir['*.jpg'].each_with_index do |filename, i|
    values = {creator: 'Jan Friedrich', copyright: 'Public Domain', comment: "This is file number #{i+1}."}
    batch.write filename, values
  end
end
if errors.empty?
  puts 'ok'
else
  puts errors
end

Deleting

# Delete ALL values
errors = MultiExiftool.delete_values(Dir['*.jpg'])
if errors.empty?
  puts 'ok'
else
  puts writer.errors
end

# Delete values for tags Author and Title
errors = MultiExiftool.delete_values(Dir['*.jpg'], tags: %w(author title))
if errors.empty?
  puts 'ok'
else
  puts writer.errors
end

Further Examples

See the examples in the examples directory.

Automatic conversion of values

By default values are converted to useful instances of Ruby classes. The following conversions are implemented at the moment:

Timestamps => Time (with local time zone of no one given)
values of form "n/m" => Rational except PartOfSet and Track

The conversion is done in the method Values#convert. So you can change it's behaviour as following examples show.

Example 1

module MyConversion
  def convert tag, val
    val # no conversion at all
  end
end

MultiExiftool::Values.prepend MyConversion

Example 2

module MultiExiftool
  module MyConversion
    def convert tag, val
      converted_val = super
      case converted_val
      when Time
        converted_val.utc # convert Time objects to utc
      when Rational
        val # no conversion
      else
        converted_val # use default conversion
      end
    end
  end

  Values.prepend MyConversion
end

Example 3

m = Module.new do
  def convert tag, val
    if val =~ MultiExiftool::Values::REGEXP_TIMESTAMP
      val # no conversion
    else
      super # use default conversion
    end
  end
end
MultiExiftool::Values.prepend m

The method Values#convert is called each time a value is fetched.

Requirements

Ruby 1.9.1 or higher
An installation of the ExifTool command-line application (version 7.65 or higher). Instructions for installation you can find under https://exiftool.org/install.html .
If you have problems with special characters (like German umlauts) in filenames on windows system it is recommended to use exiftool version 9.79 or higher.

Installation

First you need ExifTool (see under Requirements above). Then you can simply install the gem with

gem install multi_exiftool

or in your Gemfile

gem 'multi_exiftool'

Contribution

The code is also hosted in a git repository at http://github.com/janfri/multi_exiftool or https://bitbucket.org/janfri/multi_exiftool feel free to contribute!

Versioning

MultiExiftool follows Semantic Versioning, both SemVer and SemVerTag.

Author

Jan Friedrich janfri26@gmail.com

MIT License

See file LICENSE for details.

janfri / multi_exiftool