Does anyone know what bus AudioEffect StereoEnhance does? (Pan Pullout, Time Pullout, Surround sound)

Godot Version

4.2.1

Question

I’m trying to figure out what the bus audio effect StereoEnhance does exactly. The documentation on this effect is scarce. My guesses are:

  1. It encodes a stereo track with matrix surround sound by using phase inversion and delay techniques and can be decoded into 5.1 surround sound using Dolby Pro Logic II / Dolby Surround.
  2. It is a stereo widening effect similar to QSound.

This tweet talks about what StereoEnhance is likely doing. Pan pullout appears to change the width of the stereo panning. Time pullout appears to be a delay of some kind. I don’t know what surround does.

With Dolby Pro Logic II enabled, I tried pushing simple mono samples through these sliders and some other songs. It seems that pan pullout affects the position of the sound more than surround does. 0 was mono, 1 was default, and 4 sends the audio more toward the surround speakers. Additionally, setting pan pullout to 0 removed information from the audio like whole instruments, leaving only a few instruments audible. The guy I was talking to said this was because of phase cancellation.

Question was also asked on godot.community.