The score is notes: '{c1}:4 {c2}:4 {c3}:4 {c4}:4' for the keys, '{b1}:2 {b1}:2 …' for the bass and '{arp1} {arp2} {arp3} {arp4}' for the plucked arpeggio; the colours of the four bars are {k1} … {k4}. The page works out the arpeggio and the colour from the chord and calls movie.setVars(). The sound is mixed again (the report says sound mixed and how long it took); the pictures take a few milliseconds. The same tune as a file: pixi-effects render chords.html --var c1=Am --var b1=a2 ….