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• How do I get videos to upload using ruby on rails carrierwave-video ?

  9 juillet 2016, par Eric

  Updated as of July 9, 2016

  I tried to follow the instructions on the github website for the video uploader process using carrierwave-video gem but get an error that says the file or directory mmpeg -i doesn’t exist.

  The upload path for images functions correctly, just not the video one.

  I have added all of the following code necessary to help solve the error and minified as much as i possibly could.

  Video uploader code using carrierwave

  class VideoUploader < CarrierWave::Uploader::Base

    include CarrierWave::Video
  
    storage :file
  
  
  
    version :mp4 do
  
      process :encode_video => [:mp4, resolution: "100x100"]
  
    end
  
  
  
    def store_dir
  
      "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  
    end
  
  end

  Here is the movie controller code that handles uploading of videos

  class MoviesController < ApplicationController
  
     include MoviesHelper
  
  
  
     def index
  
        mode "index"
  
     end
  
  
  
     def show
  
        mode "show"
  
     end
  
  
  
     def new
  
        mode "new"
  
     end
  
  
  
     def edit
  
        mode "edit"
  
     end
  
  
  
     def create
  
        mode "create"
  
     end
  
  
  
     def update
  
        mode "update"
  
     end
  
  
  
     def destroy
  
        mode "destroy"
  
     end
  
  
  
     def review
  
        mode "review"
  
     end
  
  
  
     def approve
  
        mode "approve"
  
     end
  
  
  
     def deny
  
        mode "deny"
  
     end
  
  end

  Here is the model data for the movie that goes with it

  class Movie < ActiveRecord::Base
  
    attr_accessible :created_on, :description, :maintenance, :reviewed, :subplaylist_id, :title, :user_id, :video, :remote_video_url
  
    belongs_to :user
  
    belongs_to :subplaylist
  
    mount_uploader :video, VideoUploader
  
  end

  Here is where the movie is supposed to be displayed but it is not working

  <% provide(:title, "Movie: Where movies are made!") %>
  
  <% provide(:keywords, "movies, video") %>
  
  <% provide(:description, "This is the place where users showcase their wonderful video talent.") %>
  
  <p>&lt;%= notice %></p>
  
  <h1 class="pageheader">&lt;%= @movie.title %></h1>
  
  <br />
  
  <p class="pagetext">&lt;%= video_tag(@movie.video_url.to_s, controls: true, class: "imagebox") %></p>
  
  <p class="pagetext">&lt;%= @movie.description %></p>
  
  <p class="pagetext">Created on: &lt;%= @movie.created_on.strftime("%B-%d-%Y") %></p>
  
  <p class="pagetext">Owner: &lt;%= getType(@movie.user) %>&lt;%= link_to @movie.user.vname, user_path(@movie.user) %></p>
  
  <br />
  
  <p class="pagetext">&lt;%= link_to 'Back', mainplaylist_subplaylist_path(@subplaylist.mainplaylist, @movie.subplaylist) %></p>

  Here is where the movie new action is

  <% provide(:title, "Movie: Create new movies here!") %>
  
  <% provide(:description, "New movies are uploaded only to the site when the movie gets approved.") %>
  
  <h1 class="pagetextheader">New movie</h1>
  
  &lt;%= render 'form' %>
  
  <p class="pagetext">&lt;%= link_to 'Back', mainplaylist_subplaylist_path(@subplaylist.mainplaylist, @subplaylist) %></p>

  Here is where the movies forum parameters are

  <%= form_for([@subplaylist, @movie], :html=>{:multipart => true}) do |f| %>
  
    <% if @movie.errors.any? %>
  
      <div>
  
        <h2>&lt;%= pluralize(@movie.errors.count, "error") %> prohibited this movie from being saved:</h2>
  
  
  
        <ul>
  
        &lt;% @movie.errors.full_messages.each do |msg| %>
  
          <li>&lt;%= msg %></li>
  
        &lt;% end %>
  
        </ul>
  
      </div>
  
    &lt;% end %>
  
    <br />
  
    <div class="pagetext">
  
      &lt;%= f.label :title %><br />
  
      &lt;%= f.text_field :title %>
  
    </div>
  
    <div class="pagetext">
  
      &lt;%= f.file_field :video %>
  
    </div>
  
    <div class="pagetext">
  
      &lt;%= f.label :remote_video_url, "or video URL" %><br />
  
      &lt;%= f.text_field :remote_video_url %>
  
    </div>
  
    <div class="pagetext">
  
      &lt;%= f.label :description %><br />
  
      &lt;%= f.text_area :description %>
  
    </div>
  
    <div class="pagetext">
  
      &lt;%= f.submit %>
  
    </div>
  
    <br />
  
  &lt;% end %>

  Here is the movies helper code

  module MoviesHelper
  
  
  
     def mode(type)
  
        code = auto_logout
  
        if(code == true)
  
           sign_out
  
           redirect_to root_path
  
        else
  
           #Check if Maintenance is turned_on
  
           allmode = Maintenancemode.find_by_id(1)
  
           moviemode = Maintenancemode.find_by_id(19)
  
           mode_turned_on = (allmode.maintenance_on || moviemode.maintenance_on)
  
           #Determine if any maintenance is on
  
           if(mode_turned_on)
  
              #Determine if we are a regular user
  
              regularUser = (!current_user || !current_user.admin?)
  
              if(regularUser)
  
                 #Determine which maintenance mode is on
  
                 if(allmode.maintenance_on)
  
                    redirect_to maintenance_path
  
                 else
  
                    redirect_to movies_maintenance_path
  
                 end
  
              else
  
                 switch type
  
              end
  
           else
  
              switch type
  
           end
  
        end
  
     end
  
  
  
     private
  
        def getType(user)
  
           if(user.admin)
  
              value = "$"
  
           else
  
              typeFound = Usertype.find_by_user_id(user.id)
  
              if(typeFound)
  
                 type = typeFound.privilege
  
                 if(type == "Reviewer")
  
                    value = "^"
  
                 elsif(type == "Banned")
  
                    value = "!"
  
                 else
  
                    value = "~"
  
                 end
  
              else
  
                 value = "~"
  
              end
  
           end
  
           return value
  
        end
  
  
  
        def movieApproved
  
           movieFound = Movie.find_by_id(params[:movie_id])
  
           if(movieFound)
  
              movieFound.reviewed = true
  
              pouch = Pouch.find_by_user_id(movieFound.user_id)
  
              pointsForMovie = 10
  
              pouch.amount += pointsForMovie
  
              @pouch = pouch
  
              @pouch.save
  
              @movie = movieFound
  
              @movie.save
  
  #            MovieMailer.movie_approved(@movie, pointsForMovie).deliver
  
              redirect_to movies_review_path
  
           else
  
              render "public/404"
  
           end
  
        end
  
  
  
        def movieDenied
  
           movieFound = Movie.find_by_id(params[:movie_id])
  
           if(movieFound)
  
              #Retrieve the user who owns this pet first
  
              #userEmail = petFound.user.email
  
              #Send mail to user with link to edit the pet they sent
  
              @movie = movieFound
  
              MovieMailer.movie_denied(@movie).deliver
  
              redirect_to movies_review_path
  
           else
  
              render "public/404"
  
           end
  
        end
  
  
  
        def createMovie(subplaylistFound)
  
           newMovie = subplaylistFound.movies.new
  
           @subplaylist = subplaylistFound
  
           @movie = newMovie
  
        end
  
  
  
        def saveMovie(subplaylistFound, logged_in)
  
           newMovie = subplaylistFound.movies.new(params[:movie])
  
           newMovie.user_id = logged_in.id
  
           currentTime = Time.now
  
           newMovie.created_on = currentTime
  
           @movie = newMovie
  
           if(@movie.save)
  
              @subplaylist = subplaylistFound
  
  #            MovieMailer.review_movie(@movie).deliver
  
              flash[:success] = "#{@movie.title} is currently being reviewed please check back later."
  
              redirect_to subplaylist_movie_path(@subplaylist, @movie)
  
           else
  
              render "new"
  
           end
  
        end
  
  
  
        def switch(type)
  
           if(type == "index") #Admin only
  
              logged_in = current_user
  
              if(logged_in)
  
                 if(logged_in.admin)
  
                    allMovies = Movies.order("created_on desc").page(params[:page]).per(10)
  
                    @movies = allMovies
  
                 else
  
                    redirect_to root_path
  
                 end
  
              else
  
                 redirect_to root_path
  
              end
  
           elsif(type == "show")
  
              movieFound = Movie.find_by_id(params[:id])
  
              if(movieFound)
  
                 subplaylistFound = Subplaylist.find_by_id(params[:subplaylist_id])
  
                 if(subplaylistFound)
  
                    if(movieFound.reviewed)
  
                       @subplaylist = subplaylistFound
  
                       @movie = movieFound
  
                    else
  
                       logged_in = current_user
  
                       if(logged_in)
  
                          userMatch = ((logged_in.id == movieFound.user_id) || logged_in.admin)
  
                          if(userMatch)
  
                             @subplaylist = subplaylistFound
  
                             @movie = movieFound
  
                          else
  
                             redirect_to root_path
  
                          end
  
                       else
  
                          redirect_to root_path
  
                       end
  
                    end
  
                 else
  
                    redirect_to root_path
  
                 end
  
              else
  
                 render "public/404"
  
              end
  
           elsif(type == "new")
  
              logged_in = current_user
  
              if(logged_in)
  
                 subplaylistFound = Subplaylist.find_by_id(params[:subplaylist_id])
  
                 if(subplaylistFound)
  
                    if(subplaylistFound.collab_mode)
  
                       createMovie(subplaylistFound)
  
                    else
  
                       userMatch = (logged_in.id == subplaylistFound.user_id)
  
                       if(userMatch)
  
                          createMovie(subplaylistFound)
  
                       else
  
                          redirect_to root_path
  
                       end
  
                    end
  
                 else
  
                    render "public/404"
  
                 end
  
              else
  
                 redirect_to root_path
  
              end
  
           elsif(type == "create")
  
              logged_in = current_user
  
              if(logged_in)
  
                 subplaylistFound = Subplaylist.find_by_id(params[:subplaylist_id])
  
                 if(subplaylistFound)
  
                    if(subplaylistFound.collab_mode)
  
                       saveMovie(subplaylistFound, logged_in)
  
                    else
  
                       userMatch = (logged_in.id == subplaylistFound.user_id)
  
                       if(userMatch)
  
                          saveMovie(subplaylistFound, logged_in)
  
                       else
  
                          redirect_to root_path
  
                       end
  
                    end
  
                 else
  
                    render "public/404"
  
                 end
  
              else
  
                 redirect_to root_path
  
              end
  
           elsif(type == "edit")
  
              logged_in = current_user
  
              if(logged_in)
  
                 movieFound = Movie.find_by_id(params[:id])
  
                 if(movieFound)
  
                    userMatch = (logged_in.id == movieFound.user_id)
  
                    if(userMatch)
  
                       subplaylistFound = Subplaylist.find_by_id(movieFound.subplaylist_id)
  
                       if(subplaylistFound)
  
                          @subplaylist = subplaylistFound
  
                          @movie = movieFound
  
                       else
  
                          render "public/404"
  
                       end
  
                    else
  
                       redirect_to root_path
  
                    end
  
                 else
  
                    render "public/404"
  
                 end
  
              else
  
                 redirect_to root_path
  
              end
  
           elsif(type == "update")
  
              logged_in = current_user
  
              if(logged_in)
  
                 movieFound = Movie.find_by_id(params[:id])
  
                 if(movieFound)
  
                    userMatch = (logged_in.id == movieFound.user_id)
  
                    if(userMatch)
  
                       subplaylistFound = Subplaylist.find_by_id(movieFound.subplaylist_id)
  
                       if(subplaylistFound)
  
                          @movie = movieFound
  
                          if(@movie.update_attributes(params[:movie]))
  
                             @subplaylist = subplaylistFound
  
                             flash[:success] = 'Movie was successfully updated.'
  
                             redirect_to subplaylist_movie_path(@subplaylist, @movie)
  
                          else
  
                             render "edit"
  
                          end
  
                       else
  
                          render "public/404"
  
                       end
  
                    else
  
                       redirect_to root_path
  
                    end
  
                 else
  
                    render "public/404"
  
                 end
  
              else
  
                 redirect_to root_path
  
              end
  
           elsif(type == "destroy")
  
              logged_in = current_user
  
              if(logged_in)
  
                 movieFound = Movie.find_by_id(params[:id]) #Need to move this below the admin section to protect it
  
                 if(movieFound)
  
                    if(logged_in.admin)
  
                       subplaylistFound = Subplaylist.find_by_id(movieFound.subplaylist_id)
  
                       if(subplaylistFound)
  
                          @movie = movieFound
  
                          @subplaylist = subplaylistFound
  
                          @movie.destroy
  
                          redirect_to mainplaylist_subplaylist_path(@subplaylist.mainplaylist, @subplaylist)
  
                       else
  
                          render "public/404"
  
                       end
  
                    else
  
                       redirect_to root_path
  
                    end
  
                 else
  
                    render "public/404"
  
                 end
  
              else
  
                 redirect_to root_path
  
              end
  
           elsif(type == "review") #Admin
  
              logged_in = current_user
  
              if(logged_in)
  
                 if(logged_in.admin)
  
                    allMovies = Movie.all
  
                    moviesToReview = allMovies.select{|movie| !movie.reviewed}
  
                    @movies = Kaminari.paginate_array(moviesToReview).page(params[:page]).per(10)
  
                 else
  
                    typeFound = Usertype.find_by_user_id(logged_in.id)
  
                    if(typeFound.privilege == "Reviewer")
  
                       allMovies = Movie.all
  
                       moviesToReview = allMovies.select{|movie| !movie.reviewed}
  
                       @movies = Kaminari.paginate_array(moviesToReview).page(params[:page]).per(10)
  
                    else
  
                       redirect_to root_path
  
                    end
  
                 end
  
              else
  
                 redirect_to root_path
  
              end
  
           elsif(type == "approve") #Admin
  
              logged_in = current_user
  
              if(logged_in)
  
                 if(logged_in.admin)
  
                    movieApproved
  
                 else
  
                    typeFound = Usertype.find_by_user_id(logged_in.id)
  
                    if(typeFound.privilege == "Reviewer")
  
                       movieApproved
  
                    else
  
                       redirect_to root_path
  
                    end
  
                 end
  
              else
  
                 redirect_to root_path
  
              end
  
           elsif(type == "deny") #Admin
  
              logged_in = current_user
  
              if(logged_in)
  
                 if(logged_in.admin)
  
                    movieDenied
  
                 else
  
                    typeFound = Usertype.find_by_user_id(logged_in.id)
  
                    if(typeFound.privilege == "Reviewer")
  
                       movieDenied
  
                    else
  
                       redirect_to root_path
  
                    end
  
                 end
  
              else
  
                 redirect_to root_path
  
              end
  
           end
  
        end
  
  end

  Here is the subplaylists show code

  <% provide(:title, "Subplaylist: The place where users videos gets uploaded to!") %>
  
  <% provide(:keywords, "user, video, uploaded") %>
  
  <% provide(:description, "Allows the categorization of various videos that the user submitted successfully.") %>
  
  <p>&lt;%= notice %></p>
  
  <h1 class="pageheader">&lt;%= @subplaylist.title %></h1>
  
  <br />
  
  <p class="pagetext">&lt;%= @subplaylist.description %></p>
  
  <br />
  
  <div class="pagebox">&lt;%= paginate @movies %></div>
  
  
  
  
  
  
  
  
  
  
  
  <br />
  
  <div class="pagetext">
  
     &lt;% @movies.each_with_index do |movie, index| %>
  
        <div class="container">
  
           <div class="inner">
  
              <div class="inner">&lt;%= link_to movie.title, subplaylist_movie_path(@subplaylist, movie) %></div>
  
              &lt;% if current_user &amp;&amp; (current_user.id == movie.user_id || current_user.admin? )%>
  
                 <div class="inner">&lt;%= button_to 'Edit', edit_subplaylist_movie_path(@subplaylist, movie), method: :get %></div>
  
                 <div class="inner">&lt;%= button_to 'Destroy', [@subplaylist, movie], method: :delete, data: { confirm: 'Are you sure?' } %></div>
  
              &lt;% end %>
  
              <p>&lt;%= video_tag movie.video_url(:thumb).to_s, controls: true %></p>
  
           </div>
  
           <br />
  
           <p>Created on: &lt;%= movie.created_on.strftime("%B-%d-%Y") %></p>
  
           <p>Owner: &lt;%= getType(movie.user) %>&lt;%= link_to movie.user.vname, user_path(movie.user) %></p>
  
        </div>
  
        &lt;% if ((index + 1) % 3) == 0 %>
  
           <br />
  
           <br />
  
        &lt;% end %>
  
     &lt;% end %>
  
  </div>
  
  <br />
  
  &lt;% if current_user %>
  
     <p class="pagetext">&lt;%= link_to "New Movie", new_subplaylist_movie_path(@subplaylist) %></p>
  
     <br />
  
  &lt;% end %>
  
  <p class="pagetext">&lt;%= link_to 'Back', user_mainplaylist_path(@mainplaylist.user.vname, @subplaylist.mainplaylist.title) %></p>

  Here is the subplaylists model

  class Subplaylist < ActiveRecord::Base
  
     attr_accessible :title, :description, :collab_mode
  
     belongs_to :user
  
     belongs_to :mainplaylist
  
     has_many :movies, :foreign_key => "subplaylist_id", :dependent => :destroy
  
     VALID_NAME = /\A[A-Za-z][A-Za-z1-9][A-Za-z1-9 ]+\z/
  
     validates :title, presence: true, format: {with: VALID_NAME}
  
     validates :description, presence: true
  
  end

  Here is the subplaylists controller code

  class SubplaylistsController < ApplicationController
  
     include SubplaylistsHelper
  
  
  
     def index
  
        mode "index"
  
     end
  
  
  
     def show
  
        mode "show"
  
     end
  
  
  
     def new
  
        mode "new"
  
     end
  
  
  
     def edit
  
        mode "edit"
  
     end
  
  
  
     def create
  
        mode "create"
  
     end
  
  
  
     def update
  
        mode "update"
  
     end
  
  
  
     def destroy
  
        mode "destroy"
  
     end
  
  end

  Here is the subplaylist helper code

  module SubplaylistsHelper
  
  
  
     def mode(type)
  
        code = auto_logout
  
        if(code == true)
  
           sign_out
  
           redirect_to root_path
  
        else
  
           #Check if Maintenance is turned_on
  
           allmode = Maintenancemode.find_by_id(1)
  
           subplaylistmode = Maintenancemode.find_by_id(18)
  
           mode_turned_on = (allmode.maintenance_on || subplaylistmode.maintenance_on)
  
           #Determine if any maintenance is on
  
           if(mode_turned_on)
  
              #Determine if we are a regular user
  
              regularUser = (!current_user || !current_user.admin?)
  
              if(regularUser)
  
                 #Determine which maintenance mode is on
  
                 if(allmode.maintenance_on)
  
                    redirect_to maintenance_path
  
                 else
  
                    redirect_to subplaylists_maintenance_path
  
                 end
  
              else
  
                 switch type
  
              end
  
           else
  
              switch type
  
           end
  
        end
  
     end
  
  
  
     private
  
        def getType(user)
  
           if(user.admin)
  
              value = "$"
  
           else
  
              typeFound = Usertype.find_by_user_id(user.id)
  
              if(typeFound)
  
                 type = typeFound.privilege
  
                 if(type == "Reviewer")
  
                    value = "^"
  
                 elsif(type == "Banned")
  
                    value = "!"
  
                 else
  
                    value = "~"
  
                 end
  
              else
  
                 value = "~"
  
              end
  
           end
  
           return value
  
        end
  
  
  
        def switch(type)
  
           if(type == "show")
  
              subplaylistFound = Subplaylist.find_by_id(params[:id])
  
              if(subplaylistFound)
  
                 mainplaylistFound = Mainplaylist.find_by_title(params[:mainplaylist_id])
  
                 if(mainplaylistFound)
  
                    playlistMatch = (subplaylistFound.mainplaylist_id == mainplaylistFound.id)
  
                    if(playlistMatch)
  
                       @mainplaylist = mainplaylistFound
  
                       @subplaylist = subplaylistFound
  
                       subplaylistMovies = @subplaylist.movies.all
  
                       reviewedMovies = subplaylistMovies
  
                       if(subplaylistMovies.count > 0)
  
                          reviewedMovies = subplaylistMovies.select{|movie| movie.reviewed}
  
                       end
  
                       @movies = Kaminari.paginate_array(reviewedMovies).page(params[:page]).per(10)
  
                    else
  
                       redirect_to root_path
  
                    end
  
                 else
  
                    render "public/404"
  
                 end
  
              else
  
                 redirect_to root_path
  
              end
  
           elsif(type == "destroy")
  
              logged_in = current_user
  
              if(logged_in)
  
                 subplaylistFound = Subplaylist.find_by_id(params[:id]) #Need to move this below the admin section to protect it
  
                 if(subplaylistFound)
  
                    if(logged_in.admin)
  
                       mainplaylistFound = Mainplaylist.find_by_id(subplaylistFound.mainplaylist_id)
  
                       if(mainplaylistFound)
  
                          @subplaylist = subplaylistFound
  
                          @mainplaylist = mainplaylistFound
  
                          @subplaylist.destroy
  
                          redirect_to mainplaylist_subplaylists_path(@mainplaylist)
  
                       else
  
                          render "public/404"
  
                       end
  
                    else
  
                       redirect_to root_path
  
                    end
  
                 else
  
                    render "public/404"
  
                 end
  
              else
  
                 redirect_to root_path
  
              end
  
           end
  
        end
  
  end

  Here is the User model

  class User < ActiveRecord::Base
  
     attr_accessible :email, :first_name, :last_name, :login_id, :vname, :password, :password_confirmation, :avatar
  
     has_secure_password
  
     mount_uploader :avatar, AvatarUploader
  
     before_save { |user| user.email = user.email.downcase }
  
     before_save { |user| user.first_name = user.first_name.humanize }
  
  
  
     #key
  
     has_one :sessionkey, :foreign_key => "user_id", :dependent => :destroy
  
     has_one :usertype, :foreign_key => "user_id", :dependent => :destroy
  
  
  
     #Video section
  
     has_many :mainplaylists, :foreign_key => "user_id", :dependent => :destroy
  
     has_many :subplaylists, :foreign_key => "user_id", :dependent => :destroy
  
     has_many :movies, :foreign_key => "user_id", :dependent => :destroy
  
  
  
     #validates :first_name, presence: true
  
     VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
  
     VALID_NAME_REGEX = /\A[a-z][a-z][a-z]+\z/i
  
     VALID_VNAME_REGEX = /\A[A-Za-z][A-Za-z][A-Za-z][A-Za-z0-9 ]+([-][A-Za-z0-9 ]+)?\z/
  
     VALID_PASSWORD_REGEX = /\A[A-Za-z0-9!][A-Za-z0-9!][A-Za-z0-9!][A-Za-z0-9!][A-Za-z0-9!][A-Za-z0-9!]+\z/
  
     validates :first_name, presence: true, format: { with: VALID_NAME_REGEX}
  
     validates :last_name, presence: true, format: { with: VALID_NAME_REGEX}
  
     validates :email, presence: true, format: { with: VALID_EMAIL_REGEX}
  
     validates :login_id, presence: true, format: { with: VALID_VNAME_REGEX}, uniqueness: { case_sensitive: false}
  
     validates :vname, presence: true, format: { with: VALID_VNAME_REGEX}, uniqueness: { case_sensitive: false}
  
     validates :password, length: {minimum: 6}#, format: { with: VALID_PASSWORD_REGEX}
  
     validates :password_confirmation, presence: true #, format: { with: VALID_PASSWORD_REGEX}
  
  
  
     def to_param
  
        vname
  
     end
  
  end

  Here is the sessionkey model

  class Sessionkey < ActiveRecord::Base
  
    belongs_to :user
  
  end

  Here is the usertype model

  class Usertype < ActiveRecord::Base
  
    attr_accessible :privilege, :user_id #Only priviledge will be changeable
  
    belongs_to :user
  
  end

  Error message

  No such file or directory - ffmpeg -i /home/eric/Projects/Local/Lduelingpets/Trial/public/uploads/tmp/1466811951-3149-2702/mp4_TrialMovies.mp4

• The neutering of Google Code-In 2011

  23 octobre 2011, par Dark Shikari — development, GCI, google, x264

  Posting this from the Google Summer of Code Mentor Summit, at a session about Google Code-In !

  Google Code-In is the most innovative open-source program I’ve ever seen. It provided a way for students who had never done open source — or never even done programming — to get involved in open source work. It made it easy for people who weren’t sure of their ability, who didn’t know whether they could do open source, to get involved and realize that yes, they too could do amazing work — whether code useful to millions of people, documentation to make the code useful, translations to make it accessible, and more. Hundreds of students had a great experience, learned new things, and many stayed around in open source projects afterwards because they enjoyed it so much !

  x264 benefitted greatly from Google Code-In. Most of the high bit depth assembly code was written through GCI — literally man-weeks of work by an professional developer, done by high-schoolers who had never written assembly before ! Furthermore, we got loads of bugs fixed in ffmpeg/libav, a regression test tool, and more. And best of all, we gained a new developer : Daniel Kang, who is now a student at MIT, an x264 and libav developer, and has gotten paid work applying the skills he learned in Google Code-In !

  Some students in GCI complained about the system being “unfair”. Task difficulties were inconsistent and there were many ways to game the system to get lots of points. Some people complained about Daniel — he was completing a staggering number of tasks, so they must be too easy. Yet many of the other students considered these tasks too hard. I mean, I’m asking high school students to write hundreds of lines of complicated assembly code in one of the world’s most complicated instruction sets, and optimize it to meet extremely strict code-review standards ! Of course, there may have been valid complaints about other projects : I did hear from many students talking about gaming the system and finding the easiest, most “profitable” tasks. Though, with the payout capped at $500, the only prize for gaming the system is a high rank on the points list.

  According to people at the session, in an effort to make GCI more “fair”, Google has decided to change the system. There are two big changes they’re making.

  Firstly, Google is requiring projects to submit tasks on only two dates : the start, and the halfway point. But in Google Code-In, we certainly had no idea at the start what types of tasks would be the most popular — or new ideas that came up over time. Often students would come up with ideas for tasks, which we could then add ! A waterfall-style plan-everything-in-advance model does not work for real-world coding. The halfway point addition may solve this somewhat, but this is still going to dramatically reduce the number of ideas that can be proposed as tasks.

  Secondly, Google is requiring projects to submit at least 5 tasks of each category just to apply. Quality assurance, translation, documentation, coding, outreach, training, user interface, and research. For large projects like Gnome, this is easy : they can certainly come up with 5 for each on such a large, general project. But often for a small, focused project, some of these are completely irrelevant. This rules out a huge number of smaller projects that just don’t have relevant work in all these categories. x264 may be saved here : as we work under the Videolan umbrella, we’ll likely be able to fudge enough tasks from Videolan to cover the gaps. But for hundreds of other organizations, they are going to be out of luck. It would make more sense to require, say, 5 out of 8 of the categories, to allow some flexibility, while still encouraging interesting non-coding tasks.

  For example, what’s “user interface” for a software library with a stable API, say, a libc ? Can you make 5 tasks out of it that are actually useful ?

  If x264 applied on its own, could you come up with 5 real, meaningful tasks in each category for it ? It might be possible, but it’d require a lot of stretching.

  How many smaller or more-focused projects do you think are going to give up and not apply because of this ?

  Is GCI supposed to be something for everyone, or just or Gnome, KDE, and other megaprojects ?

• How to optimize ffmpeg w/ x264 for multiple bitrate output files

  10 octobre 2013, par Jonesy

  The goal is to create multiple output files that differ only in bitrate from a single source file. The solutions for this that were documented worked, but had inefficiencies. The solution that I discovered to be most efficient was not documented anywhere that I could see. I am posting it here for review and asking if others know of additional optimizations that can be made.

  Source file       MPEG-2 Video (Letterboxed) 1920x1080 @>10Mbps
  
                    MPEG-1 Audio @ 384Kbps
  
  Destiation files  H264 Video 720x400 @ multiple bitrates
  
                    AAC Audio @ 128Kbps
  
  Machine           Multi-core Processor

  The video quality at each bitrate is important so we are running in 2-Pass mode with the 'medium' preset

  VIDEO_OPTIONS_P2 = -vcodec libx264 -preset medium -profile:v main -g 72 -keyint_min 24 -vf scale=720:-1,crop=720:400

  The first approach was to encode them all in parallel processes

  ffmpeg -y -i $INPUT_FILE $AUDIO_OPTIONS_P2 $VIDEO_OPTIONS_P2 -b:v 250k -threads auto -f mp4 out-250.mp4 &
  ffmpeg -y -i $INPUT_FILE $AUDIO_OPTIONS_P2 $VIDEO_OPTIONS_P2 -b:v 500k -threads auto -f mp4 out-500.mp4 &
  ffmpeg -y -i $INPUT_FILE $AUDIO_OPTIONS_P2 $VIDEO_OPTIONS_P2 -b:v 700k -threads auto -f mp4 out-700.mp4 &
  

  The obvious inefficiencies are that the source file is read, decoded, scaled, and cropped identically for each process. How can we do this once and then feed the encoders with the result ?

  The hope was that generating all the encodes in a single ffmpeg command would optimize-out the duplicate steps.

  ffmpeg -y -i $INPUT_FILE \
  
  $AUDIO_OPTIONS_P2 $VIDEO_OPTIONS_P2 -b:v 250k -threads auto -f mp4 out-250.mp4 \
  
  $AUDIO_OPTIONS_P2 $VIDEO_OPTIONS_P2 -b:v 500k -threads auto -f mp4 out-500.mp4 \
  
  $AUDIO_OPTIONS_P2 $VIDEO_OPTIONS_P2 -b:v 700k -threads auto -f mp4 out-700.mp4

  However, the encoding time was nearly identical to the previous multi-process approach. This leads me to believe that all the steps are again being performed in duplicate.

  To force ffmpeg to read, decode, and scale only once, I put those steps in one ffmpeg process and piped the result into another ffmpeg process that performed the encoding. This improved the overall processing time by 15%-20%.

  INPUT_STREAM="ffmpeg -i $INPUT_FILE -vf scale=720:-1,crop=720:400 -threads auto -f yuv4mpegpipe -"
  
  
  
  $INPUT_STREAM | ffmpeg -y -f yuv4mpegpipe -i - \
  
  $AUDIO_OPTIONS_P2 $VIDEO_OPTIONS_P2 -b:v 250k -threads auto out-250.mp4 \
  
  $AUDIO_OPTIONS_P2 $VIDEO_OPTIONS_P2 -b:v 500k -threads auto out-500.mp4 \
  
  $AUDIO_OPTIONS_P2 $VIDEO_OPTIONS_P2 -b:v 700k -threads auto out-700.mp4

  Does anyone see potential problems with doing it this way, or know of a better method ?