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What is hydra-file_characterization?

Provides a wrapper for file characterization.

Product Owner & Maintenance

hydra-file_characterization is a Core Component of the Samvera community. The documentation for what this means can be found here.

Product Owner



The Samvera community is here to help. Please see our support guide.

Getting Started

If you are using Rails add the following to an initializer (./config/initializers/hydra-file_characterization_config.rb):

Hydra::FileCharacterization.configure do |config|
  config.tool_path(:fits, '/path/to/fits')
Hydra::FileCharacterization.characterize(File.read(filename), File.basename(filename), :fits)
  • Why file.read? To highlight that we want a string. In the case of ActiveFedora, we have a StringIO instead of a file.
  • Why file.basename? In the case of Fits, the characterization takes cues from the extension name.

You can call a single characterizer...

xml_string = Hydra::FileCharacterization.characterize(File.read("/path/to/my/file.rb"), 'file.rb', :fits)

...for this particular call, you can specify custom fits path...

xml_string = Hydra::FileCharacterization.characterize(contents_of_a_file, 'file.rb', :fits) do |config|
  config[:fits] = './really/custom/path/to/fits'

...or even make the path callable...

xml_string = Hydra::FileCharacterization.characterize(contents_of_a_file, 'file.rb', :fits) do |config|
  config[:fits] = lambda {|filename|  }

...or even create your custom characterizer on the file...

xml_string = Hydra::FileCharacterization.characterize(contents_of_a_file, 'file.rb', :my_characterizer) do |config|
  config[:my_characterizer] = lambda {|filename|  }

You can also call multiple characterizers at the same time.

fits_xml, ffprobe_xml = Hydra::FileCharacterization.characterize(contents_of_a_file, 'file.rb', :fits, :ffprobe)

Registering New Characterizers

This is possible by adding a characterizer to the Hydra::FileCharacterization::Characterizers' namespace.


  1. bundle install
  2. Increase the version number in lib/hydra/file_characterization/version.rb
  3. Increase the same version number in .github_changelog_generator
  4. Update CHANGELOG.md by running this command:
  github_changelog_generator --user samvera --project hydra-file_characterization --token YOUR_GITHUB_TOKEN_HERE
  1. Commit these changes to the master branch
  2. Run rake release


This software has been developed by and is brought to you by the Samvera community. Learn more at the Samvera website.

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