Dragonfly FTW

gistfile1.rb

require 'transcoder/base'
require 'transcoder/video'

class Content < ActiveRecord::Base

  image_accessor :cover_image do
    after_assign :make_preview_video
  end
  image_accessor :preview_video
  
  attr_accessible :name, :content, :cover_image
  
  def thumbnail
    cover_image.thumb("100x100").jpg
  end
  
  def preview
    cover_image.thumb("555x>").jpg
  end
  
  def mobile_preview
    cover_image.thumb("600x").jpg
  end
  
  def make_preview_video
    return unless cover_image.ext == "mov"
    out_file = File.new("/tmp/#{rand}.mp4", "a")
    Transcoder::Video.new.transcode(cover_image.path, out_file.path)
    self.preview_video = out_file
    self.save!
  end
end