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- // Copyright 2006, Thomas Scott Stillwell
- // All rights reserved.
- //
- //Redistribution and use in source and binary forms, with or without modification, are permitted
- //provided that the following conditions are met:
- //
- //Redistributions of source code must retain the above copyright notice, this list of conditions
- //and the following disclaimer.
- //
- //Redistributions in binary form must reproduce the above copyright notice, this list of conditions
- //and the following disclaimer in the documentation and/or other materials provided with the distribution.
- //
- //The name of Thomas Scott Stillwell may not be used to endorse or
- //promote products derived from this software without specific prior written permission.
- //
- //THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
- //IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
- //FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
- //BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- //(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
- //PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- //STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
- //THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- desc:compressor/limiter, similar to F670
-
- slider1:0<-60,0,0.1>Threshold (dB)
- slider2:70<0.1,100,0.1>Bias
- slider3:0<-30,30,0.1>Makeup gain
- slider4:0<0,1,1{Left/Right,Lat/Vert}>AGC
- slider5:1<1,6,1>Time Constant
- slider6:100<1,10000,1>Level detector RMS window
- slider7:1<1,50,0.1>Current comp. ratio
- slider8:0<-90,0,0.1>Gain reduction
-
- @init
- log2db = 8.6858896380650365530225783783321; // 20 / ln(10)
- db2log = 0.11512925464970228420089957273422; // ln(10) / 20
- i=0;
- attime=0.0002; //200us
- reltime=0.300; //300ms
- rmstime=0.000050; //50us
- maxover=0;
- ratio=0;
- cratio=0;
- rundb=0;
- overdb=0;
- maxover=0;
- atcoef=exp(-1/(attime * srate));
- relcoef=exp(-1/(reltime * srate));
- rmscoef=exp(-1/(rmstime * srate));
- leftright = 0;
- latvert = 1;
-
- @slider
- thresh = slider1;
- threshv = exp(thresh * db2log);
- ratio = 20;
- bias = 80 * slider2 / 100;
- cthresh = thresh - bias;
- cthreshv = exp(cthresh * db2log);
- makeup = slider3;
- makeupv = exp(makeup * db2log);
- agc = slider4;
- timeconstant = slider5;
- timeconstant == 1 ? (
- attime = 0.0002;
- reltime = 0.300;
- );
- timeconstant == 2 ? (
- attime = 0.0002;
- reltime = 0.800;
- );
- timeconstant == 3 ? (
- attime = 0.0004;
- reltime = 2.000;
- );
- timeconstant == 4 ? (
- attime = 0.0008;
- reltime = 5.000;
- );
- timeconstant == 5 ? (
- attime = 0.0002;
- reltime = 10.000;
- );
- timeconstant == 6 ? (
- attime = 0.0004;
- reltime = 25.000;
- );
- atcoef = exp(-1 / (attime * srate));
- relcoef = exp(-1 / (reltime * srate));
-
- rmstime = slider6 / 1000000;
- rmscoef=exp(-1/(rmstime * srate));
-
- @sample
- agc == leftright ? (
- aspl0 = abs(spl0);
- aspl1 = abs(spl1);
- ) : (
- aspl0 = abs(spl0+spl1)/2;
- aspl1 = abs(spl0-spl1)/2;
- );
-
- maxspl = max(aspl0, aspl1);
- maxspl = maxspl * maxspl;
-
- runave = maxspl + rmscoef * (runave - maxspl);
- det = sqrt(max(0,runave));
-
- overdb = 2.08136898 * log(det/threshv) * log2db;
- overdb = max(0,overdb);
-
- overdb > rundb ? (
- rundb = overdb + atcoef * (rundb - overdb);
- ) : (
- rundb = overdb + relcoef * (rundb - overdb);
- );
- overdb = max(rundb,0);
-
- bias == 0 ? (
- cratio = ratio;
- ) : (
- cratio = 1 + (ratio-1) * sqrt((overdb + dcoffset) / (bias + dcoffset));
- );
- slider7 = cratio;
-
- gr = -overdb * (cratio-1)/cratio;
- slider8 = -gr;
- grv = exp(gr * db2log);
-
- agc == leftright ? (
- spl0 *= grv * makeupv;
- spl1 *= grv * makeupv;
- ) : (
- sav0 = (spl0 + spl1) * grv;
- sav1 = (spl0 - spl1) * grv;
- spl0 = makeupv * (sav0 + sav1) * 0.5;
- spl1 = makeupv * (sav0 - sav1) * 0.5;
- );
-
-