peaceful and mindful multiformat video encoding with Zencoder API
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Gives you has_video_encodings method for your models, that sets up jobs to encode multiple video container/codecs using Zencoder. It tells Zencoder to place the output files in some bucket in your S3 account. From there, they are yours to enjoy forever.

class Video < ActiveRecord::Base

  has_video_encodings :video_files, :formats            => [:ogg, :mp4, :webm, :flv],
                                    :output_dimensions  => '852x480',
                                    :s3_config          => "#{Rails.root}/config/amazon_s3.yml",
                                    :path               => "videos/zc/:title_to_slug/",
                                    :thumbnails         => { :number => 2, :aspect_mode => 'crop', 'size' => '290x160' },
                                    :options            => { :device_profile => 'mobile/advanced' }



developed on ruby 1.9.2-p290 and Rails 3.1.3

  1. A Zencoder account of course, testing or full.

  2. A working Amazon S3 account with a shiny new bucket ready to receive video files.

  3. this gem (zencodable) in your gemfile, and typhoeus.

    gem 'zencodable'
    gem 'typhoeus' # NOTE: for heroku deploys, pin to 0.2.4


Zencoder API keys and initializer settings

the zencoder gem expects access to your Zencoder API keys in some fashion. Also, typhoeus is a big improvement for HTTP stuffs. Thirdly, Zencoder's API v2 (soon to be released as of 2011-12-4) is full of options, has more progress information and much more hotness - so let's use that!.

So, I like something in config/initializers/zencoder.rb like

# zencoder setup
if Rails.env == 'production'
  Zencoder.api_key = 'yourproductionkey'
  Zencoder.api_key = 'keyfortestingacct'

Zencoder::HTTP.http_backend = Zencoder::HTTP::Typhoeus

Zencoder.base_url = ''

Bucket policy

The bucket needs to have a custom policy to allow Zencoder to place the output videos on it. Here is a guide on Zencoder's site, follow it

(There is currently a branch where an attempt to create a rake task to auto-install this policy was made. Unfortunately it seems the marcel/aws-s3 gem doesn't know how to update a bucket policy after all, it just manages the ACLs. It seems fog can't do that either. Oh well, you'll have to paste in the policy.)

Run the generator

rails generate zencodable:migration <Model> <association_name>


rails generate zencodable:migration KittehVideo kitteh_video_files

This will actually create two has_many associations for your model - the kitteh_video_files for the output files themselves (one for each format), and the kitteh_video_file_thumbnails for the framegrab thumbnails that Zencoder can create (if configured).

you can add a --skip-thumbnails option if you don't want to use the auto-generated thumbnails.

now do a rake db:migrate

How to use

Configure model and encoding options

add something like the above has_video_encodings class method to your model (the generator does not try to do this for you).

The options should include a :s3_config key that gives a location of a YAML file containing your S3 credentials, which should contain a 'bucket' key (you already have one, right?) Actually, all we need from that is the bucket name, so you can instead use a :bucket key to give the name of the bucket where the output files should be placed.

:formats is a list of output formats you'd like. Supported formats and codecs

The :path is the path within the bucket where the output files should be placed. It can contain one or more :some_method tokens, which will be replaced with the (String) results of calling the given method on your record. i.e., given

class Video < ActiveRecord::Base
  has_video_encodings :video_files, :path => 'some/path/:project_id/:slug'

  def project_id;; end
  def slug; title.to_slug; end

the paths within your S3 bucket will look like /some/path/12493/lion-eats-kitteh/.

The individual object names will be based on a sanitized version of the original file name - all non-alphanumerics are removed.

The other options are all those that can be handled by Zencoder. More info can be found on :thumbnails, :output_dimensions and other output settings :options

Give it a source URL

All that's needed to trigger the Zencoder job is to change the origin_url value of your model, and then save. That will be picked up, sent to Zencoder, and your job will be started with your desired settings.

As the job runs, you can check Model.job_status as you see fit, if the job is neither failed nor finished, it will request an update from Zencoder for that Job.

Individual files will complete at different times, so you can also check the state of each associated output file.

vid = :title => 'Hilarious Kitteh Antics!'
vid.origin_url = '[HD].mov'
vid.job_status # "new"
vid.job_status # "waiting"
vid.job_status # "processing"
vid.video_encoded_files.collect { |v| [v.format, v.state] }
vid.job_status # "finished"
vid.video_encoded_files.size # 4
vid.video_encoded_file_thumbnails.size # 2


  • rake task to generate a working bucket policy (even if it has to be pasted in)
  • set timeouts on update_job
  • create DJ and/or Resque workers to handle job submission (should be optional dependencies though)
  • generator to install config/initializer
  • remove files from S3 when object is deleted
  • background jobs to update the ZC job progress, with events/notifications
  • use API v2 features to get more interesting info on job progress
  • is s3_url basename sanitization going to be good for non-ASCII filenames? no.


Uses MIT-LICENSE. You are free to use this as you like, but don't expect anything.

Forking and pull requests would be much appreciated.