How to create a video upload platform using Ruby on Rails – Part 2

Welcome back to part 2 of How to create a video upload platform using Ruby on Rails. In Part 1, we worked on setting up the basic Ruby on Rails application that allowed us to upload, store, and playback video files from our app. In this next part, we are going to enhance that process some by adding some FFMPEG Transcoding. This way, we can get all videos that are uploaded converted into a common format that will make it easier to work with on the playback side.

So lets get started. The first thing we need to do is make sure we have ffmpeg installed. On mac this is pretty simple using brew. If you don’t have HomeBrew installed, please follow the directions at If you are on another linux or windows system, there are many guides online to help set ffmpeg up for you. Once you have that installed, we can install the ffmpeg command:

brew install ffmpeg

I decided to install a lot of the extra ffmpeg options to make sure I had the best compatibility. Here is a more complete line

brew install ffmpeg --with-chromaprint --with-fdk-aac --with-libass --with-librsvg --with-libsoxr --with-libssh --with-tesseract --with-libvidstab --with-opencore-amr --with-openh264 --with-openjpeg --with-openssl --with-rtmpdump --with-rubberband --with-sdl2 --with-snappy --with-tools --with-webp --with-x265 --with-xz --with-zeromq --with-zimg

Once you have ffmpeg installed and running we need to add the carrierwave-video gem to our project:

# Gemfile
gem "carrierwave-video"

Next, we need to update our upload to include this new library. Open the app/uploaders/video_uploader.rb file and add the following include line to it:

class VideoUploader < CarrierWave::Uploader::Base
 include CarrierWave::Video # <== Add this line here

In order for Carrierwave to actually encode the video, we need to also add a line that instructs it to do so. Lets also adjust the resolution while we are at it.

class VideoUploader < CarrierWave::Uploader::Base
  include CarrierWave::Video

  process encode_video: [:mp4, resolution: "640x480"]


The last thing we need to do is change the file extension. If we upload an avi or mov file, we convert that to mp4 but with Carrierwave it will maintain the original extension. So add the following lines right after the process line added above

def full_filename(for_file)
  super.chomp(File.extname(super)) + '.mp4'

def filename
  original_filename.chomp(File.extname(original_filename)) + '.mp4'

Fire up your Rails app and upload a video just like we did in Part 1. You should see the following in your Rails console. Notice the line Running transcoding...

Started POST "/videos" for at 2018-05-17 09:41:10 -0400
Processing by VideosController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"pCgWw3lxulQ9qiGxfck5oqFXgQo0tqO7gG371YEbFaiiRMdAc98uPGQCvTYzn0/Kub/pQtQI9n95I+grmGvQ6w==", "video"=>{"title"=>"adf", "file"=>#<ActionDispatch::Http::UploadedFile:0x007fbb5f814be8 @tempfile=#<Tempfile:/var/folders/__/7ns9m_817l71zfd0xw5618n00000gn/T/>, @original_filename="", @content_type="video/quicktime", @headers="Content-Disposition: form-data; name=\"video[file]\"; filename=\"\"\r\nContent-Type: video/quicktime\r\n">}, "commit"=>"Create Video"}
I, [2018-05-17T09:41:10.439284 #60568]  INFO -- : Running transcoding...
["/usr/local/bin/ffmpeg", "-y", "-i", "/Sites/VideoSite/tmp/1526564470-60568-0006-7430/", "-vcodec", "libx264", "-acodec", "aac", "-s", "640x480", "-r", "30", "-strict", "-2", "-map_metadata", "-1", "-aspect", "1.3333333333333333", "/Sites/VideoSite/tmp/1526564470-60568-0006-7430/tmpfile.mp4"]

I, [2018-05-17T09:41:17.640387 #60568]  INFO -- : Transcoding of /Sites/VideoSite/tmp/1526564470-60568-0006-7430/ to /Sites/VideoSite/tmp/1526564470-60568-0006-7430/tmpfile.mp4 succeeded

   (0.3ms)  begin transaction
  SQL (0.3ms)  INSERT INTO "videos" ("title", "file", "created_at", "updated_at") VALUES (?, ?, ?, ?)  [["title", "adf"], ["file", "step.mp4"], ["created_at", "2018-05-17 13:41:17.643006"], ["updated_at", "2018-05-17 13:41:17.643006"]]
   (1.0ms)  commit transaction
Redirected to http://localhost:3000/videos/1
Completed 302 Found in 7260ms (ActiveRecord: 1.6ms)


There we go. We are now successfully encoding the video file to a common format using ffmpeg. In the next part we will look at moving this process to the background so that we don’t force the user to wait on the transcoding, and add some status indications of how the progress is going. Until next time!

Create FFMPEG processor for Carrierwave in Rails 3

I have had the pleasure of working with the carrierwave gem recently (as opposed to paperclip), and I must say, I am quite the fan. Once major thing I missed however, was the available list of custom user plugins for it, unlike paperclip. I believe this is mostly due to how new and recent carrierwave is. That being said, I put together a simple example of a FFMPEG process that will allow me to resample the bitrate of a file. This should lay the ground work for other features as well. This example is using Rails 3, but should be easily adaptable for 2. Also, make sure you already have FFMPEG installed and running properly. So lets get started: First things first…we need to add the appropriate gems to our Gemfile:

# Gemfile
gem "carrierwave"
gem "streamio-ffmpeg"

Next is the meat and potatoes of this..the actual FFMPEG process for carrierwave. I choose to keep my plugin files in the directory lib/carrierwave. Make sure you have this path included in your application.rb file if you are using rails 3. Here is the code:

# lib/carrierwave/ffmpeg.rb
require "streamio-ffmpeg"
module CarrierWave
  module FFMPEG
    module ClassMethods
      def resample( bitrate )
        process :resample => bitrate
    def resample( bitrate )
      directory = File.dirname( current_path )
      tmpfile = File.join( directory, "tmpfile" )
      File.move( current_path, tmpfile )
      file =
      file.transcode( current_path, :audio_bitrate => bitrate)
      File.delete( tmpfile )

Good. Now that we have the plugin coded up, we need to include it into our uploader. I already have one mounted to my Asset model. Here is what my AssetUploader now looks like:

# app/uploaders/asset_uploader.rb
require File.join(Rails.root, "lib", "carrier_wave", "ffmpeg")

class AssetUploader < CarrierWave::Uploader::Base
  include CarrierWave::FFMPEG # <= include the plugin
  # Choose what kind of storage to use for this uploader:
  storage :file

  # Override the directory where uploaded files will be stored.
  # This is a sensible default for uploaders that are meant to be mounted:
  def store_dir
  # Add a version, utilizing our processor
  version :bitrate_128k do
    process :resample => "128k"

There! Now whenever you add a new file, it should fire off the processor and create a new version. I hope this help anyone still up in the air about how to put together their own plugin/process for carrierwave. Next I will demonstrate how to incorporate Delayed::Job to move these intensive tasks to the background!