pub fn amp_gain(
envelope: f64,
velocity: f64,
velocity_track: f64,
voice_amplitude: f64,
) -> f64Expand description
The voice gain after the amplitude envelope:
(envelope * lerp(1, velocity, velocity_track) * voice_amplitude)^2.
The square means that a measured RMS contour maps to the square root of
the envelope level. Renders on the open engine confirm the square for
the sustain level, the velocity and voice_amplitude.