It is counterintuitive and meaningless to use a value larger than 1.0 to indicate slower playback. Use 0,9 to indicate a speed of 90% of the original speed or use a percentage to indicate the relative speed. 120% is as clear as 1,20x and 0,75 or 75% doesn't make much difference but 1,25x brake is a bad way to indicate slower playback. I'm not even sure which value in percent that translates to.