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• Background Video Processing with Rails

  23 octobre 2013, par Matthew Snyder

  I am trying to get uploaded videos to be converted in the background, running windows. Some of what I am using :

  gem 'paperclip'
  
  gem 'delayed_job_active_record'
  
  gem 'ffmpeg'

  I have edited the registry to allow the ffmpeg command to be ran from anywhere, I get a popup that I assume is ffmpeg because it goes away too quickly, guess the command is wrong so if anyone knows what's wrong with it please let me know. But the real problem is that it just hangs there, it says :

  [2012-12-09 22:47:03] ERROR invalid body size.
  
  [2012-12-09 22:47:03] ERROR Errno::ECONNABORTED: An established connection was a
  
  borted by the software in your host machine.
  
          C:/RailsInstaller/Ruby1.9.3/lib/ruby/1.9.1/webrick/httpresponse.rb:396:i
  
  n `write'
  
          C:/RailsInstaller/Ruby1.9.3/lib/ruby/1.9.1/webrick/httpresponse.rb:396:i
  
  n `<<'
  
          C:/RailsInstaller/Ruby1.9.3/lib/ruby/1.9.1/webrick/httpresponse.rb:396:i
  
  n `_write_data'
  
          C:/RailsInstaller/Ruby1.9.3/lib/ruby/1.9.1/webrick/httpresponse.rb:368:i
  
  n `send_body_string'
  
          C:/RailsInstaller/Ruby1.9.3/lib/ruby/1.9.1/webrick/httpresponse.rb:249:i
  
  n `send_body'
  
          C:/RailsInstaller/Ruby1.9.3/lib/ruby/1.9.1/webrick/httpresponse.rb:152:i
  
  n `send_response'
  
          C:/RailsInstaller/Ruby1.9.3/lib/ruby/1.9.1/webrick/httpserver.rb:110:in
  
  `run'
  
          C:/RailsInstaller/Ruby1.9.3/lib/ruby/1.9.1/webrick/server.rb:191:in `blo
  
  ck in start_thread'

  Does anyone know how to properly get this working ? I've went through a few tutorials that have bits and pieces of what I need but I can't get them working together. Here's what I have so far, lemme know if you need more :

  Model :

  class Video < ActiveRecord::Base
  
  
  
    belongs_to :user
  
    has_many :comments, dependent: :destroy
  
    attr_accessible :video, :user_id, :video_file_name, :title, :public, :description, :views
  
  
  
    has_attached_file :video, url: "/users/:user_id/videos/:id/:basename_:style.:extension"
  
  
  
    #process_in_background :video #causes death
  
  
  
    validates :video, presence: true
  
    validates :description, presence: true, length: { minimum: 5, maximum: 100}
  
    validates :title, presence: true, length: { minimum: 1, maximum: 15 }
  
  
  
    validates_attachment_size :video, less_than: 1.gigabytes
  
    validates_attachment :video, presence: true
  
  
  
    default_scope order: 'created_at DESC'
  
  
  
    Paperclip.interpolates :user_id do |attachment, style|attachment.instance.user_id
  
    end
  
  
  
    #before_post_process do |video|
  
     # false if video.status == "converting"
  
    #end
  
  
  
    def perform
  
      command = <<-end_command
  
        start ffmpeg -i #{ '/public/users/:user_id/videos/:id/:basename_:style.:extension' }  -ar 22050 -ab 32 -s 1280x720 -vcodec webm -r 25 -qscale 8 -f webm -y #{ '/public/users/:user_id/videos/:id/:basename_.webm' }
  
  
  
      end_command
  
      success = system(command)
  
      logger.debug 'Converting File: ' + success.to_s
  
      if success && $?.exitstatus.to_i == 0
  
        #self.converted!
  
        self.status = "converted"
  
      else
  
        #self.failure!
  
        self.status = "failed"
  
      end
  
    end
  
  
  
    handle_asynchronously :perform
  
  
  
    def self.search(search)
  
      if search
  
        find(:all, conditions: ["public = 't' AND title LIKE ?", "%#{search}%"], order: "created_at DESC")
  
      else
  
        find(:all, conditions: ["public = 't'"], order: "created_at DESC")
  
      end
  
    end
  
  
  
    def self.admin_search(search)
  
      if search
  
        find(:all, conditions: ['title LIKE ?', "%#{search}%"], order: "created_at DESC")
  
      else
  
        find(:all, order: "created_at DESC")
  
      end
  
    end
  
  
  
    private
  
  
  
      # This updates the stored filename with the new flash video file
  
      def set_new_filename
  
        #update_attribute(:filename, "#{filename}.#{id}.webm")
  
        update_attribute(:content_type, "video/x-webm")
  
      end
  
  
  
  end

  Controller :

  class VideosController < ApplicationController
  
      before_filter :signed_in_user, only: [:upload, :update, :destroy]
  
      before_filter :admin_user, only: :admin_index
  
  
  
      def upload
  
          @video = Video.new
  
          # generate a unique id for the upload
  
          @uuid = (0..29).to_a.map {|x| rand(10)}
  
      end
  
  
  
      def create
  
          @video = Video.new(params[:video])
  
          @video.user_id = current_user.id
  
  
  
          if @video.save
  
              @video.delay.perform
  
              flash[:success] = "Uploaded Succefully!"
  
              redirect_to @video.user
  
              Delayed::Worker.new.start
  
          else
  
              render 'upload'
  
          end
  
      end
  
  
  
      def show
  
          @video = Video.find(params[:id])
  
          @comments = @video.comments.paginate(page: params[:page], per_page: 6)
  
          if !@video.public
  
              if !signed_in? || current_user.id != @video.user_id  && !current_user.admin && !current_user.approved?(@video.user)
  
              flash[:notice] = "Video is private"
  
              redirect_to root_path
  
          end
  
      end
  
      end
  
  
  
      def update
  
          @video = Video.find(params[:id])
  
          if @video.update_attributes(params[:video])
  
        flash[:success] = "Video preferences saved"
  
      else
  
          flash[:fail] = "Failed to update video preferences"
  
      end
  
      redirect_to :back
  
    end
  
  
  
      def destroy
  
          @video = Video.find(params[:id])
  
          @video.destroy
  
          flash[:deleted] = "Deleted Succefully!"
  
          redirect_to :back
  
      end
  
  
  
      def index
  
          @videos = Video.paginate(page: params[:page], per_page: 6).search(params[:search])
  
      end
  
  
  
      def admin_index
  
          @videos = Video.paginate(page: params[:page], per_page: 6).admin_search(params[:search])
  
      end
  
  
  
      def ajax_video_comments
  
          @video = Video.find(params[:id])
  
          @comments = @video.comments.paginate(page: params[:page], per_page: 6)
  
  
  
          respond_to do |format|
  
          format.js   { render partial: 'shared/comments', content_type: 'text/html' }
  
      end
  
      end
  
  
  
      def ajax_video_watched
  
          @video = Video.find(params[:id])
  
          @video.views += 1
  
          @video.save
  
      end
  
  
  
      private
  
  
  
      def signed_in_user
  
          redirect_to root_path, notice: "Please Login." unless signed_in?
  
      end
  
  
  
      def admin_user
  
          redirect_to(root_path) unless current_user.admin?
  
      end
  
  
  
  end

• What Every Programmer Should Know

  24 décembre 2012, par Multimedia Mike — General

  During my recent effort to force myself to understand Unicode and modern text encoding/processing, I was reminded that this is something that “every programmer should just know”, an idea that comes up every so often, usually in relation to a subject in which the speaker is already an expert. One of the most absurd examples I ever witnessed was a blog post along the lines of “What every working programmer ought to know about [some very specific niche of enterprise-level Java programming]“. I remember reading through the article and recognizing that I had almost no knowledge of the material. Disturbing, since I am demonstrably a “working programmer”.

  For fun, I queried the googles on the matter of what ever programmer ought to know.

  Specific Topics
  Here is what every programmer should know about : Unicode, time, memory (simple), memory (extremely in-depth), regular expressions, search engine optimization, floating point, security, basic number theory, race conditions, managed C++, VIM commands, distributed systems, object-oriented design, latency numbers, rate monotonic algorithm, merging branches in Mercurial, classes of algorithms, and human names.

  Broader Topics
  20 subjects every programmer should know, 97 things every programmer should know, 12 things every programmer should know, things every programmer should know (27 items), 10 papers every programmer should read at least twice, 10 things every programmer should know for their first job.

  Meanwhile, I remain fond of this xkcd comic whose mouseover text describes all that a person genuinely needs to know. Still, the new year is upon us, a time when people often make commitments to bettering themselves, and it couldn’t hurt (much) to at least skim some of the lists and find out what you never knew that you never knew.

  What About Multimedia ?
  Reading the foregoing (or the titles of the foregoing pieces), I naturally wonder if I should write something about what every programmer should know about multimedia. I think it would look something like a multimedia programming FAQ. These are some items that I can think of :

  1. YUV : The other colorspace (since most programmers are only familiar with RGB and have no idea what to make of the YUV that comes out of most video decoding APIs)
  2. Why you can’t easily seek randomly to any specific frame in a video file (keyframe/interframe discussion and their implications)
  3. Understand your platform before endeavoring to implement multimedia software (modern platforms, particularly mobile platforms, probably provide everything you need in the native APIs and there is likely little reason to compile libavcodec for the platform)
  4. Difference between containers and codecs (longstanding item, but I would argue it’s less relevant these days due to standardization on the MPEG — MP4/H.264/AAC — stack)
  5. What counts as a multimedia standard in this day and age (comparing the foregoing MPEG stack with the WebM/VP8/Vorbis stack)
  6. Trade-offs to consider when engineering a multimedia solution
  7. Optimization doesn’t always work the way you think it does (not everything touted as a massive speed-up in the world of computing — whether it be multithreaded CPUs, GPGPUs, new SIMD instruction sets — will necessarily be applicable to multimedia processing)
  8. A practical guide to legal issues would not be amiss
  9.  ???

  What other items count as “something multimedia-related that every programmer should know” ?

• avformat/utils : Keep internal and external av_read_frame() packets in sync.

  23 mai 2013, par Dale Curtis

  avformat/utils : Keep internal and external av_read_frame() packets in sync.
  Otherwise, during error conditions, the caller will be left with
  
  dangling pointers to a destructed packet => boom.
  BUG=242786
  
  TEST=ffmpeg_regression_tests
  Commit slightly simplified by commiter
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavformat/utils.c