This gem serves as the basis for the interface between a Ruby (Rails) application and a provider of transcoding services such as Opencast Matterhorn, Zencoder, Shingoncoder, and Amazon Elastic Transcoder.


Add this line to your application's Gemfile:

gem 'active_encode'

And then execute:

$ bundle

Or install it yourself as:

$ gem install active_encode


Set the engine adapter (default: inline), configure it (if neccessary), then submit encoding jobs!

ActiveEncode::Base.engine_adapter = :matterhorn

Create returns an encoding job that has been submitted to the encoding engine for processing. At this point it will have an id, a state, the input, and any additional information the encoding engine returns.

#<ActiveEncode::Base:0x00000003f3cd90 @input="http://localhost:8080/files/mediapackage/edcac316-1f98-44b1-88ca-0ce6f80aebc0/ff43c56f-7b8f-4d9c-a846-6e51de2e8cb4/Bars_512kb.mp4", @options={:preset=>"avalon", :stream_base=>"file:///home/cjcolvar/Code/avalon/avalon/red5/webapps/avalon/streams"}, @id="12154", @state=:running, @current_operations=[], @percent_complete=0.0, @output=[], @errors=[], @tech_metadata={}>  # "12103"
encode.state  # :running

This encode can be looked back up later using #find. Alternatively, use #reload to refresh an instance with the latest information from the

encode = ActiveEncode::Base.find("12103")

Progress of a running encode is shown with a current operation (multiple possible if outputs are generated in parallel) and percent complete. Technical metadata about the input file is added by the encoding engine. This should include a mime type, checksum, duration, and basic technical details of the audio and video content of the file (codec, audio channels, bitrate, framerate, and dimensions). Outputs are added once they are created and should include the same technical metadata along with an id, label, and url.

If the encoding job should be stopped, call cancel:

encode.cancelled?  # true

If the encoding job should be deleted, call purge:


Purge will attempt to remove all outputs that have been generated. It is also possible to remove only a single output using its id:

encode.remove_output! 'track-9'

An encoding job is meant to be the record of the work of the encoding engine and not the current state of the outputs. Therefore removing outputs will not be reflected in the encoding job.

Custom jobs

Subclass ActiveEncode::Base to add custom callbacks or default options. Available callbacks are before, after, and around the create, cancel, and purge actions.

class CustomEncode < ActiveEncode::Base
  after_create do "Created encode with id #{}"

  def self.default_options(input)
    {preset: 'avalon-skip-transcoding'}

Engine Adapters

Engine adapters are shims between ActiveEncode and the back end encoding service. Each service has its own API and idiosyncracies so consult the table below to see what features are supported by each adapter. Add an additional engines by creating an engine adapter class that implements :create, :find, :list, :cancel, :purge, and :remove_output.

Adapter/Feature Create Find List Cancel Purge Remove Output Preset Multiple Outputs
Matterhorn X X X X X X X
Zencoder X X X
Shingoncoder (prototype) X X
Shingoncoder X X
AWS Elastic Transcoder X X X
Inline X X
Test X X X X


  1. Fork it ( )
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create a new Pull Request