gistfile1.rb

      # The flag used to set video bitrate has apparently changed between 
      # different ffmpeg versions. In the latest builds -b is used. 
      # In older builds it was -v which is now used to set verbosity of logging.
      cattr_accessor :video_bit_rate_parameter
      self.video_bit_rate_parameter = "b"
      
      include AbstractTool::InstanceMethods
      
      attr_reader :frame, :q, :size, :time, :output_bitrate, :video_size, :audio_size, :header_size, :overhead, :psnr, :output_fps
      
      # Not sure if this is needed anymore...
      def tool_command
        'ffmpeg'
      end
      
      def format_fps(params={})
        "-r #{params[:fps]}"
      end
      
      def format_video_bit_rate(params = {})
        "-#{video_bit_rate_parameter} #{params[:video_bit_rate]}k"
      end
      
      def format_video_quality(params={})
        bitrate = params[:video_bit_rate].blank? ? nil : params[:video_bit_rate]
        factor = (params[:scale][:width].to_f * params[:scale][:height].to_f * params[:fps].to_f)
        case params[:video_quality]
        when 'low'
          bitrate ||= (factor / 12000).to_i
          params[:video_bit_rate] = bitrate
          " #{format_video_bit_rate params} -crf 30 -me zero -subq 1 -refs 1 -threads auto "
        when 'medium'
          bitrate ||= (factor / 9000).to_i
          " #{format_video_bit_rate params} -crf 22 -flags +loop -cmp +sad -partitions +parti4x4+partp8x8+partb8x8 -flags2 +mixed_refs -me hex -subq 3 -trellis 1 -refs 2 -bf 3 -b_strategy 1 -coder 1 -me_range 16 -g 250"
        when 'high'
          bitrate ||= (factor / 3600).to_i
          " #{format_video_bit_rate params} -crf 18 -flags +loop -cmp +sad -partitions +parti4x4+partp8x8+partb8x8 -flags2 +mixed_refs -me full -subq 6 -trellis 1 -refs 3 -bf 3 -b_strategy 1 -coder 1 -me_range 16 -g 250 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71"
        else
          ""
        end
      end