2.0 to 5.0 Upmix (M).txt

desc:Based on DTS Neural Upmix (Medium)

slider1:100<0,100,2>Center Level Control
slider2:4000<1000,10000,1000>rear LP freq  (Hz)

@init
shape = 0.2 //filter shape (0=sharp, 1=dull)
// @slider
// gain = 2^(slider1/6); // convert from dB to a multiplier
// depth_temp=(slider1*$pi)/200; //depth scaled from 0-100 to 0>half pi
// R_width_coeff=slider2/100;

@slider
  damp=0.01+shape*20;
  c = 1/tan($pi*slider2/srate);
  fk = 1 / (1 + c*(c+damp));
  fa1 = 2 * (1 - c*c) * fk;
  fa0 = (1 + c*(c-damp)) * fk;
  //damp!=oldamp ? fd1l=fd2l=fd1r=fd2r=0;
  oldamp=damp;

@sample
mid= spl0+spl1;
side=spl0-spl1;

spl0 = (0.20*mid) + (side*0.3) + (mid *0.25*(1-(slider1/100))) ; 
spl1 = (0.20*mid) - (side*0.3) + (mid *0.25*(1-(slider1/100)) ); 
spl2 = mid * 0.5 * (slider1/100); 

// spl3 = 0; unneeded?

//some code from lowpass

spl4 = 0.5*side; //preupscale

fd0l = (fk*spl4) - (fa1*fd1l) - (fa0*fd2l);//LPing the rear(s)
spl4 = fd0l + fd1l + fd1l + fd2l;
fd2l = fd1l;//previous buffers etc
fd1l = fd0l;

spl5 = spl4;