Custom volume curve

[codeabuse]

• Linear input/volume replaced by exponent of 2^(-5 * input)
• TODO: create more curves and menu items to switch between them

[not-holar]

Please see #1 (comment)

The exponentiation is usually only needed when the volume changing is done by multiplying the raw input signal samples.

As the addon app ties the volume slider to the VM's slider, the exponentiation is already being done by Voicemeeter itself.

The double exponentiation makes the transfer curve overshoot in the other direction and essentially makes the slider-gain relation unnatural again in terms of perceived volume.

I would suggest changing the minimum value of the lerp from -60 to -96 (https://github.com/not-holar/volume_control_for_voicemeeter/blob/main/src%2Fmain.rs#L154) instead of doing another curve on top. That should achieve complete parity with how windows does device volume sliders.