lala.rb

pipe = "kikou.png"

(1..100).step(0.5) do |time|
  begin
    retries ||= 0
    Timeout::timeout(5) do
      fork do
        `#{command(time, score_crop_options, pipe)}` # runs ffmpeg, writes frame into `pipe`
        exit
      end

      # read image from pipe.
      # blocking (until ffmpeg writes into the pipe)
      image = read_image

      # do stuff with image
    end
  rescue Timeout::Error => e
    retry if (retries += 1) < 3
  end
end