Add this line to your application's Gemfile:

gem 'miniatura'

And then execute:

$ bundle

Or install it yourself as:

$ gem install miniatura

In the Rails app/uploaders/filename.rb, call the generate_thumb function with options. The options are passed as hash to this function, can be also empty.

The options are:

• size - The height x width of the thumbnail to be generated, by default will take the same size of that of the video, type is string.
• file_extension - Format of the file to be saved, by default the format at will be "jpeg", type is string.
• quality - Quality of the file to be saved, type is integer.
• time_frame - The time in the video at which the thumbnail must be generated, type is string.

Here's a working example:

In your Rails app/uploaders/video_uploader.rb:

class VideoUploader < CarrierWave::Uploader::Base
  include CarrierWave::RMagick
  include Miniatura
  storage :file

  version :thumb do
    process generate_thumb:[{size: 200,quality: 5, file_extension: "jpeg"}]
    def full_filename for_file
      png_name for_file, version_name, "jpeg"
    end
  end

  def png_name for_file, version_name, format
    %Q{#{version_name}_#{for_file.chomp(File.extname(for_file))}.#{format}}
  end

  def store_dir
    "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  end
end

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/miniatura. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

The gem is available as open source under the terms of the MIT License.