anchor.diff:    (/ (length (mp3-file-samples mp3)) 
        (* (mp3-file-channels mp3) (mp3-file-sample-rate mp3))))
   
  -(defun make-movie (directory mp3-name final-name tmp-name &optional (remove-tmp t))
  +(defun make-movie (directory mp3-name final-name tmp-name &optional (remove-tmp t) (bit-rate (* 4 2014)))
     "Run ffmpeg to create a movie with audio."
     (if (probe-file tmp-name)
         (delete-file tmp-name))
   
     (let ((movie-command
            (format nil 
  -                 "ffmpeg -r 30 -i \"~aframe%05d.png\" -b 2400 -q 4 \"~a\""
  -                 directory tmp-name))
  +                 "ffmpeg -r 30 -i \"~aframe%05d.png\" -b ~a -q 4 \"~a\""
  +                 directory bit-rate tmp-name))
           (audio-command
            (format nil
                    "ffmpeg -i \"~a\" -i \"~a\" -codec copy -shortest \"~a\""
  
positive.code:     
      (cl-cairo2:scale 1 1)
      (cl-cairo2:set-line-width 0.5)
      (cl-cairo2:set-source-rgba 0.0 0.8 0.0 0.95)
      (flet ((cairo-line (x1 y1 x2 y2)
               (cl-cairo2:move-to x1 y1)
               (cl-cairo2:line-to x2 y2)
  
negative.code:            (funcall
              color-function
              0.0
              (+ 0.3 (/ (* i 0.6) (spirograph-steps sp)))
              0.0
              0.95)
             (funcall
  