ffmpeg & carrierwave

ffmpeg.rb

module CarrierWave
  module FFMPEG
    extend ActiveSupport::Concern

    module ClassMethods
      def faststart
        process :faststart => true
      end
      
      def transcode options
        process :transcode => options
      end
      
      def send_thumbnail_to method_name
        process :send_thumbnail_to => method_name
      end
    end

    def transcode *args
      options = args.inject({}){|o, p| o[p.first] = p.last; o } # combining hash from array of pairs
      options = {:custom => rotation_filters}.merge(options)
      transcoder_options = {
          :preserve_aspect_ratio => options.delete(:preserve_aspect_ratio),
          :max_dimensions => options.delete(:max_dimensions)
      }
      
      with_temp_filepath do |temp_path|
        FileUtils.mv current_path, temp_path
        
        file = MovieWithRotationSupport.new temp_path
        file.transcode current_path, options, transcoder_options
      end
    end

    def faststart _
      with_temp_filepath do |temp_path|
        FileUtils.mv current_path, temp_path
        
        puts 'Applying qt-faststart'
        `qt-faststart #{temp_path} #{current_path}`
      end
    end

    def send_thumbnail_to method_name
      with_temp_filepath ['thumbnail', '.jpg'] do |temp_path|
        file = MovieWithRotationSupport.new current_path
        file.transcode temp_path, :custom => "-ss 00:00:01 -vframes 1 -f image2 #{rotation_filters}"
      
        model.send method_name, File.new(temp_path)
      end
    end

    private
    
    def with_temp_filepath basename = 'video'
      tmpfile = Tempfile.new basename
      tmpfile.close
      
      yield tmpfile.path
    ensure
      tmpfile.unlink
    end
    
    def rotation_filters
      case MiniExiftool.new(current_path).rotation
        when 180
          '-vf "vflip,hflip"'
        when 90
          '-vf "transpose=1"'
        when 270
          '-vf "transpose=2"'
        else
          ''
      end
    end
    
    class MovieWithRotationSupport < ::FFMPEG::Movie
      attr_reader :rotation
      
      def initialize path
        super
        @rotation = MiniExiftool.new(path).rotation
        @resolution = @resolution.split('x').reverse.join('x') if rotated?
      end
      
      def transcode(output_file, options = EncodingOptions.new, transcoder_options = {}, &block)
        TranscoderWithMaxDimensionsSupport.new(self, output_file, options, transcoder_options).run &block
      end
      
      protected
      
      def rotated?
        @rotation % 180 != 0
      end
    end
    
    class TranscoderWithMaxDimensionsSupport < ::FFMPEG::Transcoder
      def apply_transcoder_options
        super
        return if @movie.calculated_aspect_ratio.nil?
        
        if @transcoder_options[:max_dimensions]
          new_height = @movie.height
          new_width = @movie.width
          if new_width > @raw_options.width
            new_width = @raw_options.width
            new_height = new_width / @movie.calculated_aspect_ratio
            new_height = new_height.ceil.even? ? new_height.ceil : new_height.floor
            new_height += 1 if new_height.odd? # needed if new_height ended up with no decimals in the first place
          end
          if new_height > @raw_options.height
            new_height = @raw_options.height
            new_width = new_height * @movie.calculated_aspect_ratio
            new_width = new_width.ceil.even? ? new_width.ceil : new_width.floor
            new_width += 1 if new_width.odd?
          end
          
          if @raw_options[:custom] && @raw_options[:custom]['transpose']
            @raw_options[:resolution] = "#{new_height}x#{new_width}"
          else
            @raw_options[:resolution] = "#{new_width}x#{new_height}"
          end
          @raw_options[:aspect] = new_width.to_f / new_height.to_f
        end
      end
    end
  end
end

video_uploader.rb

class VideoUploader < CarrierWave::Uploader::Base
  include CarrierWave::MimeTypes
  include CarrierWave::FFMPEG

  storage :fog

  def store_dir
    "uploads/#{model.class.table_name}/#{mounted_as}/#{model.id}"
  end
  
  process :set_content_type

  version :default do
    process :send_thumbnail_to => :photo=,
            :transcode => {
                :audio_codec => 'copy',
                :video_codec => 'libx264',
                :video_bitrate => 500,
                :resolution => '640x640',
                :max_dimensions => true
            },
            :faststart => true
  end

  def extension_white_list
     %w(mov mp4 mpe mpg m4v)
  end
end