musicdsp.org source code archive - WSInf

Millimeter to DB (faders...) (click this to go back to the index)
References : Posted by James McCartney
Notes :
These two functions reproduce a traditional professional
mixer fader taper.
MMtoDB converts millimeters of fader travel from the
bottom of the fader for a 100 millimeter fader into
decibels. DBtoMM is the inverse.
The taper is as follows from the top:
The top of the fader is +10 dB
100 mm to 52 mm : -5 dB per 12 mm
52 mm to 16 mm : -10 dB per 12 mm
16 mm to 4 mm : -20 dB per 12 mm
4 mm to 0 mm : fade to zero. (in these functions I go to -200dB
which is effectively zero for up to 32 bit audio.)
Code :
float MMtoDB(float mm)
{
float db;
}
mm = 100. - mm;
if (mm = 10.) {
mm = 0.;
} else if (db > -10.) {
mm = -12./5. * (db - 10.);
} else if (db > -40.) {
mm = 48. - 12./10. * (db + 10.);
} else if (db > -60.) {
mm = 84. - 12./20. * (db + 40.);
} else if (db > -200.) {
mm = 96. - 1./35. * (db + 60.);
} else mm = 100.;
}
mm = 100. - mm;
return mm;
Comments
from : Christian@savioursofsoul.de
comment : Pascal Translation...
function MMtoDB(Milimeter:Single):Single;
var mm: Single;
begin
mm:=100-Milimeter;
if mm = 0 then Result:=10
else if mm < 48 then Result:=10-5/12*mm;
else if mm < 84 then Result:=-10-10/12*(mm-48);
else if mm < 96 then Result:=-40-20./12*(mm-84);
else if mm < 100 then Result:=-60-35*(mm-96);
else Result:=-200.;
end;
function DBtoMM(db:Single):Single;
begin
if db>=10 then result:=0;
else if db>-10 then result:=-12/5*(db-10);
else if db>-40 then result:=48-12/10(db+10);
else if db>-60 then result:=84-12/20(db+40);
else if db>-200 then result:=96-1/35(db+60);
else result:=100.;
Result:=100-Result;
end;