#PGDWN add chapter -1 # skip to previous chapter
#Shift+PGUP seek 600
#Shift+PGDWN seek -600
-[ multiply speed 1/1.1 # scale playback speed
-] multiply speed 1.1
+[ add speed -0.1 # scale playback speed
+] add speed 0.1
{ multiply speed 0.5
} multiply speed 2.0
#BS set speed 1.0 # reset speed to normal