add video converter worker and task

app/workers/convert_video_worker.rb

+class ConvertVideoWorker
+  include Sidekiq::Worker
+  include RepositoriesProxy
+
+  sidekiq_options queue: :convert_video
+
+  def perform(id)
+    object = learning_object_repository.find @learning_object.id
+
+    # convert if object has a flv and not a mp4
+    flv = nil
+    object.attachments.each do |attachment|
+      flv = attachment if attachment.name =~ /.flv$/i
+
+      return true if attachment.name =~ /.mp4$/i
+    end
+    return true if flv.nil?
+
+    dspace_client = DspaceService.create_client
+
+    # retrieve video from dspace
+    video = dspace_client.bitstreams.retrieve(id: flv.id)
+
+    # open video with ffmpeg
+    # FFMPEG.ffmpeg_binary = '/usr/local/bin/ffmpeg'
+    FFMPEG.ffmpeg_binary = 'ffmpeg'
+    file = ::FFMPEG::Movie.new(video.path)
+    return false unless file.valid? # if ffmpeg fails to read the movie
+
+    converted_path = "#{video.path}.mp4"
+
+    # transcode (convert video to mp4)
+    options = {
+                video_codec: "libx264",
+                x264_preset: "fast",
+                custom: '-movflags +faststart -pix_fmt yuv420p -profile:v main -level 3.1 -refs 4 -c:a libfdk_aac',
+                validate: true
+              }
+    file.transcode(converted_path, options)
+
+    converted = File.open converted_path
+
+    # send converted video to dspace
+    dspace_client.items.add_bitstream(converted, id: object.id_dspace, name: "#{flv.name.split('.')[0..-2].join('.')}.mp4", description: 'converted from original flv')
+
+    # remove temp files
+    video.unlink
+    converted.close
+    FileUtils.rm converted_path, force: true
+  end
+
+end

config/sidekiq.yml

@@ -10,6 +10,7 @@
 :queues:
   - default
   - score
+  - convert_video
   - [high_priority, 2]
 # :daemon: true
 

lib/tasks/convert_video.rake

+namespace :score do
+
+  desc "Generate Score"
+  task :learning_object => :environment do
+    include RepositoriesProxy
+
+    # Quantity of items fetched on each iteration
+    limit = 500
+
+    # Start point from where items will be fetched
+    offset = 0
+
+    loop do
+
+      begin
+        # Get items from dspace (from offset to offset+limit)
+        items = learning_object_repository.all_from_offset_to_limit(offset,limit)
+      rescue
+        # Sleeps for a while to wait database's recovery
+        sleep(10.seconds)
+        # Goes to next iteration to retry
+        next
+      else
+        # Terminate loop if there are no more items to import
+        break if items.empty?
+
+        items.each do |item|
+          item.attachments.each do |attachment|
+            ConvertVideoWorker.perform_async(item.id) if attachment.name =~ /.flv$/i
+          end
+        end
+
+        # Increment offset, to get new items on next iteration
+        offset += limit
+      end
+    end
+  end
+
+end