Small ruby class that uses FFmpeg to perform PSNR analysis on two video files.

compare.rb

require "pathname"
require "open3"

class CompareVideo
  def initialize(reference, video)
    ref = Pathname.new(File.open("#{reference}", "r"))
    vid = Pathname.new(File.open("#{video}", "r"))
    @comp = [vid, ref]  # Video first, reference file second
  end
  def compare(tech=['psnr','ssim'])
    @res = {}
    tech.each do |niq|
      puts "TASK: " + niq
      stdout, stderr, status = Open3.capture3('ffmpeg', '-y', '-i',
                                              "#{@comp[1]}", '-i',
                                              "#{@comp[0]}", '-filter_complex',
                                              "#{niq}", 'outputfile.mp4')
      puts "STATUS: " + (status.success? ? 'succeeded' : 'failed')
      @res[niq] = stderr
    end
  end
  def analyze
    psnr_avg = @res['psnr'].scan(/average:\d+.?\d+/).to_s.delete! 'average:'
    psnr = psnr_avg.gsub(/[\"\[\]]/, "").to_f
    puts "PSNR score: " + psnr.to_s
    ssim_res = @res['ssim'].scan(/All:\d+.?\d+/).to_s.delete! 'All:'
    ssim = ssim_res.gsub(/[\"\[\]]/, "").to_f
    puts "SSIM response: " + ssim.to_s
    return [psnr, ssim]
  end
end