Time Source : How It Works

On AmbienceSource there are 2 choices of time source : Unscaled (default) and Scaled. This page explains how Tiny Ambience achieve it for all types of layers. The purpose of this article is... for your peace of mind. (That's why it is here in Advanced tab!)

I believe a plugin should have as few black boxes as possible. I hope you don't need this page in order to hot fix my bugs...

Unscaled

Intended behaviour is that ambience is unaffected when you change Time.timeScale.

You may think "Of course not!" because you are used to AudioSource which doesn't get messed up no matter what Time.timeScale you use. But there are more to the party in Tiny Ambience that needs "fixing".

Layer Mode : Looping Clip

Looping Clip layer can have Speed Automation curve. The curve is run by legacy and lightweight Animation component. Unlike the more costly Animator component, this component do not have adjustable time source to be unscaled and by default is affected by Time.timeScale.

To fix, Tiny Ambience counter-adjust the AnimationState normalizedSpeed as an inverse of the current Time.timeScale to make it appears like nothing had happened. e.g. If time scale is 0.3, then animation play head speed becomes 1 / 0.3 = 3.33, nullifying the time scale. Everything (volume, speed, pan) will automate as designed regardless of Time.timescale.

Layer Mode : One Shot Program

One Shot Program use Time.realtimeSinceStartup to determine when should the shot be fired. There is nothing to fix here since One Shot Program does not really have a "play head", it just waits and fires.

Layer Mode : Timeline

This is an easy one, we can just choose director mode UnscaledGameTime and everything should work as intended.

Scaled

Intended behaviour is that ambience is affected when you change Time.timeScale, that is, if you decrease Time.timeScale to be below 1.00 the sound should be slow and stretched out, like horror sound. Using 0 Time.timeScale will make the ambience stop.

Layer Mode : Looping Clip

The automation curve that is run by legacy and lightweight Animation component is already affected by Time.timeScale so we don't have to fix that.

But we have got new problems. AudioSource does not get stretched out by Time.timeScale by default, so to simulate the stretching out we need to modify the .pitch accordingly.

That presents a new problem if the layer has Speed Automation curve. The .pitch adjustment earlier will be overwritten by the curve. We have to make a new curve that has all keyframes scaled by the current Time.timeScale to be correct. This curve will also run in slower/faster play head according to Animation component's default behaviour.

Though, Tiny Ambience will modify the inside of AnimationCurve instead of literally making a new curve. The AnimationCurve is a class and we could have GC allocation on every change of Time.timeScale. Rather, Keyframe inside the curve are struct and would be released cleanly when going out of scope. We surgically replace all the Keyframe inside.

Layer Mode : One Shot Program

Instead of using Time.realtimeSinceStartup to determine where to fire the next shot, it collects Time.deltaTime instead. The shot firing interval is now scaled to time.

To match the longer interval, all AudioSource that would get PlayOneShot then received .pitch that would make them more stretched out when played. Everything related to audio length (e.g. "From Clip Length" interval mode) also needs the value increased/decreased accordingly.

Lastly, adjusting Time.timeScale while a shot is firing may not produce a completely accurate result. For example, the audio maybe able to go from normal speed to slow speed mid-way, but the wait interval registered is already decided to use the normal one instead of slower one. Tiny Ambience make sure it at least sounds correct when you went crazy on Time.timeScale adjustments. Timing maybe off a bit.

Layer Mode : Timeline

This is again, an easy one. We can just choose director mode GameTime and everything should work as intended.