drive

How hard the music is pushing: loud for this song AND busy.

Use this for speed. energy alone is not enough, because it is measured against the song's own range, so the loudest moment of a lullaby scores the same as the loudest moment of a drum track. That is right for deciding how big to draw something, and wrong for deciding how fast to fly: it would send the camera hurtling through a ballad. Mixing in mood, which knows how often things are happening, keeps a calm song calm while still letting it breathe.

It is zero while nothing is audible. A paused player keeps its levels and its mood on screen, and a song's silent opening carries the section's mood, so the parts alone would keep pushing; the music pushes only while it is heard.