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• Why iFrame is a good idea

  15 octobre 2009

  I’ve seen some hilariously uninformed posts about the new Apple iFrame specification. Let me take a minute to explain what it actually is.

  First off, as opposed to what the fellow in the Washington Post writes, it’s not really a new format. iFrame is just a way of using formats that we’ve already know and love. As the name suggests, iFrame is just an i-frame only H.264 specification, using AAC audio. An intraframe version of H.264 eh ? Sounds a lot like AVC-Intra, right ? Exactly. And for exactly the same reasons - edit-ability. Whereas AVC-Intra targets the high end, iFrame targets the low end.

  Even when used in intraframe mode, H.264 has some huge advantage over the older intraframe codecs like DV or DVCProHD. For example, significantly better entropy coding, adaptive quantization, and potentially variable bitrates. There are many others. Essentially, it’s what happens when you take DV and spend another 10 years working on making it better. That’s why Panasonic’s AVC-Intra cameras can do DVCProHD quality video at half (or less) the bitrate.

  Why does iFrame matter for editing ? Anyone who’s tried to edit video from one of the modern H.264 cameras without first transcoding to an intraframe format has experienced the huge CPU demands and sluggish performance. Behind the scenes it’s even worse. Because interframe H.264 can have very long GOPs, displaying any single frame can rely on dozens or even hundreds of other frames. Because of the complexity of H.264, building these frames is very high-cost. And it’s a variable cost. Decoding the first frame in a GOP is relatively trivial, while decoding the middle B-frame can be hugely expensive.

  Programs like iMovie mask that from the user in some cases, but at the expensive of high overhead. But, anyone who’s imported AVC-HD video into Final Cut Pro or iMovie knows that there’s a long "importing" step - behind the scenes, the applications are transcoding your video into an intraframe format, like Apple Intermediate or ProRes. It sort of defeats one of the main purposes of a file-based workflow.

  You’ve also probably noticed the amount of time it takes to export a video in an interframe format. Anyone who’s edited HDV in Final Cut Pro has experienced this. With DV, doing an "export to quicktime" is simply a matter of Final Cut Pro rewriting all of the data to disk - it’s essentially a file copy. With HDV, Final Cut Pro has to do a complete reencode of the whole timeline, to fit everything into the new GOP structure. Not only is this time consuming, but it’s essentially a generation loss.

  iFrame solves these issues by giving you an intraframe codec, with modern efficiency, which can be decoded by any of the H.264 decoders that we already know and love.

  Having this as an optional setting on cameras is a huge step forward for folks interested in editing video. Hopefully some of the manufacturers of AVC-HD cameras will adopt this format as well. I’ll gladly trade a little resolution for instant edit-ability.

• sh : ffmpeg : not found on Heroku

  18 octobre 2015, par joël

  I am using paperclip gem and piperclip-ffmpeg on a Rails 3.1 setup.

  After deploying to Heroku, I am getting this error after uploading a video.

  sh: ffmpeg: not found on Heroku

  My Model

  class Video < ActiveRecord::Base
  
  
  
    has_attached_file :asset, :styles => { 
  
      :medium => { :geometry => "640x480", :format => 'video/mpeg' },
  
      :thumb => { :geometry => "100x100#", :format => 'jpg', :time => 10 }
  
    }, :processors => [:ffmpeg]
  
  end

  I’d be surprised if ffmpeg not available on Heroku, but that’s may be the problem.

  Any suggestions ?

• Rails 3 : How can I make Paperclip-FFMPEG work ?

  9 novembre 2011, par remino

  I have Rails 3.0.3 with these gems :

  • delayed_job 2.1.4
  • delayed_paperclip 0.7.1
  • paperclip 2.3.16
  • paperclip-ffmpeg 0.7.0

  (This combination is very specific. Some newer gems will not work with others.)

  Here's my Video model :

  class Video < Upload
  
    has_attached_file :file, :default_style => :view, :processors => [:ffmpeg],
  
      :url => '/system/:class/:attachment/:id/:style/:basename.:extension',
  
      :path => ':rails_root/public/system/:class/:attachment/:id/:style' \
  
        + '/:basename.:extension',
  
      :default_url => '/images/en/processing.png',
  
      :styles => {
  
        :mp4video => { :geometry => '520x390', :format => 'mp4',
  
          :convert_options => { :output => { :vcodec => 'libx264',
  
            :vpre => 'ipod640', :b => '250k', :bt => '50k',
  
            :acodec => 'libfaac', :ab => '56k', :ac => 2 } } },
  
        :oggvideo => { :geometry => '520x390', :format => 'ogg',
  
          :convert_options => { :output => { :vcodec => 'libtheora',
  
            :b => '250k', :bt => '50k', :acodec => 'libvorbis',
  
            :ab => '56k', :ac => 2 } } },
  
        :view => { :geometry => '520x390', :format => 'jpg', :time => 1 },
  
        :preview => { :geometry => '160x120', :format => 'jpg', :time => 1 }
  
      }
  
    validates_attachment_content_type :file, :content_type => VIDEOTYPES,
  
      :if => Proc.new { |upload| upload.file.file? }
  
    process_in_background :file
  
  end

  When creating a new Video object with attachment, the original is saved, but no conversion will be done. Even calling Video.last.file.reprocess! won't to a thing except returning true. (Not sure what "true" means in this case as it didn't work.)

  I tried hardcoding the path to ffmpeg in Paperclip::options[:command_path]. I even tried deleting the paperclip-ffmpeg.rb file and replacing it with a blank file. Really thinking I'd get an exception by doing the later, instead, I simply got "true" again.

  It feels like the paperclip-ffmpeg.rb is being loaded, because it is required by config/application.rb, but nothing is called in it when trying to generate a thumbnail or convert a video.

  Can anyone help me with this ? Thanks in advance !