Function rms_to_meter_level 

pub fn rms_to_meter_level(rms: f32) -> f32

Convert a linear RMS value ([0, 1]) into a UI-meter level ([0, 1]) on a logarithmic dBFS scale, with 0 dBFS mapping to 1.0 and METER_FLOOR_DBFS mapping to 0.0.

Linear RMS is a useless meter input because human loudness perception (and microphone signal) is logarithmic — speech sits around -30 dBFS (RMS ≈ 0.03), while the linear scale would map the same speech to ~3 % of a 10-bar meter. The dBFS-mapped output puts conversational speech around 50 % of the bar, leaving headroom at both ends for whispers + shouts.

Indicative outputs (for the default -60 dBFS floor):

Input RMS	dBFS	Meter level
0.0	-∞	0.00
0.001	-60	0.00
0.003	-50.5	0.16
0.01	-40	0.33
0.03	-30.5	0.49
0.1	-20	0.67
0.3	-10.5	0.83
1.0	0	1.00