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Guest skibby

so I wrote a Vocoder in JS to sound like a Bode

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Guest skibby



it was designed to perform super well with super low saw waves like that one song in Syro *thanks Richard*

it uses the same frequencies as a bode vocoder

i spent the past four days actually coding this because i wasnt happy with any other vocoders.

theres still room for improvement, lots of optimisation, etc


and the code, for use in ReaJS

//Vocoder 14 nov 2014 Thanks SaulT and Amateur Tools DSP

//This plugin contains ideas and code techniques by RBJ, SaulT, Moog, Bode, Loser, etc.

//USE AT OWN RISK. This plugin could turn you into a human centipede.


desc:Zhaozhou's Vocoder - carrier chans 1+2, modulator chans 3+4

slider1:0<-50,1000,0.5>Frequency Base Shift (hz)

slider6:0<-24,24,1>Carrier Amt

slider8:0<-24,24,1>Mod Amt

slider14:-90<-120,6,1>Threshold (db)

slider16:20<1,100,1>Fadein (ms)

slider18:20<1,100,1>Fadeout (ms)

slider20:20<1,100,1> RMS smoothing (ms)

slider60:-120<-120,6,0.01>Dry Mod Signal

slider62:7000<104.5,20000,1>Dry Mod Highpass Filter

slider64:0<-120,6,0.01> Main Out Amp


// Freqs from Bode Vocoder (centered) \

f1=104.5; f2=179.5; f3=226; f4=284.5;

f5=358.5; f6=452; f7=569.5; f8=717.5;

f9=904; f10=1139; f11=1435; f12=1808;

f13=2260; f14=2852; f15=3616; f16=4556;

// Q's aka 'damp' for bandpass filters

q1=0.008; q2=0.05; q3=0.02; q4=0.03;

q5=0.03; q6=0.03; q7=0.03; q8=0.04;

q9=0.04; q10=0.04; q11=0.04; q12=0.04;

q13=.03; q14=0.05; q15=0.05; q16=0.05; q17=0.3;

// PCB trimpots for adjusting carriers after filters

trim1=0.2; trim2=0.2; trim3=0.01; trim4=0.4;

trim5=0.4; trim6=0.4; trim7=0.5; trim8=0.5;

trim9=0.6; trim10=0.6; trim11=0.7; trim12=0.7;

trim13=0.8; trim14=0.8; trim15=0.9; trim16=0.9;

// PCB trimpots for adjusting modulators after filters

// trim17=1.25; trim18=0.25; trim19=0.35; trim20=0.35;

// trim21=0.45; trim22=0.45; trim23=0.6; trim24=0.65;

// trim25=0.8; trim26=0.9; trim27=1; trim28=1.25;

// trim29=1.5; trim30=1.5; trim31=2; trim32=2;

// PCB trimpots for adjusting modulators after filters

trim17=49; trim18=3; trim19=100; trim20=4;

trim21=6; trim22=9; trim23=12; trim24=12;

trim25=15; trim26=25; trim27=30; trim28=40;

trim29=55; trim30=60; trim31=90; trim32=110;

// used by rbj filter

cDcAdd = 10^-30;

cDenorm = 10^-30;

// bandpass filter

function bp(in,freq,damp)



damp=damp*0.999 + 0.001;

c = ( 1 / tan( $pi*freq / srate ) );

a = 1 + c*(c+damp);

fa = 2 * (1 - c*c) / a;

fb = (1 + c*(c-damp)) / a;

fk = c*damp / a;

d = fk*in - (fa*fd + fb*fc);

in = d - fc;

fc = fd;

fd = d;


// lowpass for c1,m1

function lp(in,freq)



a9 = 1;

s9 = 2;

q9 = 1 / (sqrt((a9 + 1/a9)*(1/s9 - 1) + 2));

w09 = 2 * $pi * freq/srate;

cosw09 = cos(w09);

sinw09 = sin(w09);

alpha9 = sinw09 / (2 * q9);

b09 = (1 - cosw09)/2;

b19 = (1 - cosw09);

b29 = (1 - cosw09)/2;

a09 = 1 + alpha9;

a19 = -2 * cosw09;

a29 = 1 - alpha9;

b09 /= a09;

b19 /= a09;

b29 /= a09;

a19 /= a09;

a29 /= a09;

old = in;

in = b09 * in + b19 * x19 + b29 * x29 - a19 * y19 - a29 * y29;

x29 = x19;

x19 = old;

y29 = y19;

y19 = in;


//highpass filter rbj

function hp(in,freq)



hp_f = 2 * $pi * freq/srate;

a0 = 1; //start coeffs

s0 = 1;

q0 = 1 / (sqrt((a0 + 1/a0)*(1/s0 - 1) + 2));

cosw00 = cos(hp_f);

sinw00 = sin(hp_f);

alpha0 = sinw00 / (2 * q0);

b00 = (1 + cosw00)/2;

b10 = -(1 + cosw00);

b20 = (1 + cosw00)/2;

a00 = 1 + alpha0;

a10 = -2 * cosw00;

a20 = 1 - alpha0;

b00 /= a00;

b10 /= a00;

b20 /= a00;

a10 /= a00;

a20 /= a00;

hp_f != 0 ? ( //start hp filter

old_in = in;

in = b00 * in + b10 * x10 + b20 * x20 - a10 * y10 - a20 * y20;

x20 = x10;

x10 = old_in;

y20 = y10;

y10 = abs(in) < cDenorm ? 0 : in;



function g(in) // gate

instance(a,silentcnt,seekto,g8) //fadein and out are global


a=abs(in) > thresh;

a ?




) : (

(silentcnt+=1) > 2205 ? seekto=0;


seekto > 0.5 ?


g8=g8*fadein + (1-fadein);

) : (




// smoothing out the audio rate stuff

function rms(in)



rms_coeff = exp(-1/(slider20 * srate * 0.001));

rms_s = (rms_s * rms_coeff) + ((1 - rms_coeff) * in * in);




//freqs and freq adjust

f1=104.5+slider1; f2=179.5+slider1; f3=226+slider1; f4=284.5+slider1;

f5=358.5+slider1; f6=452+slider1; f7=569.5+slider1; f8=717.5+slider1;

f9=904+slider1; f10=1139+slider1; f11=1435+slider1; f12=1808+slider1;

f13=2260+slider1; f14=2852+slider1; f15=3616+slider1; f16=4556+slider1;


thresh = 2 ^ (slider14/6);

fadein = 1/pow(10,1/(srate*slider16/1000));

fadeout = 1/pow(10,1/(srate*slider18/1000));


rms_coeff = exp(-1/(slider20 * srate * 0.001));

// gain amps

c_amt = 10^(slider6/20); //Carrier amt

m_amt = 10^(slider8/20); //Modulator amt

d_amt = 10^(slider60/20); //Dry Mod amt

o_amt = 10^(slider64/20); //main out


// dc fix, denormals

spl0 += cDcAdd;

spl1 += cDcAdd;




//carrier filter array \\\\\\\\

c1= c1_lp.lp( c_in,f1 ) *trim1;

c2=c2_.hp( c2_bp.bp( c_in,f2,q2 ) ,f2 )*trim2;

c3=c3_.hp( c3_bp.bp( c_in,f3,q3 ) ,f3 )*trim3;

c4=c4_.hp( c4_bp.bp( c_in,f4,q4 ) ,f4 )*trim4;

c5=c5_.hp( c5_bp.bp( c_in,f5,q5 ) ,f5 )*trim5;

c6=c6_.hp( c6_bp.bp( c_in,f6,q6 ) ,f6 )*trim6;

c7=c7_.hp( c7_bp.bp( c_in,f7,q7 ) ,f7 )*trim7;

c8=c8_.hp( c8_bp.bp( c_in,f8,q8 ) ,f8 )*trim8;

c9=c9_.hp( c9_bp.bp( c_in,f9,q9 ) ,f9 )*trim9;

c10=c10_.hp( c10_bp.bp( c_in,f10,q10 ),f10 )*trim10;

c11=c11_.hp( c11_bp.bp( c_in,f11,q11 ),f11 )*trim11;

c12=c12_.hp( c12_bp.bp( c_in,f12,q12 ),f12 )*trim12;

c13=c13_.hp( c13_bp.bp( c_in,f13,q13 ),f13 )*trim13;

c14=c14_.hp( c14_bp.bp( c_in,f14,q14 ),f14 )*trim14;

c15=c15_.hp( c15_bp.bp( c_in,f15,q15 ),f15 )*trim15;

c16=c16_.hp( c16_bp.bp( c_in,f16,q16 ),f16 )*trim16;

//Modu Sig Chain

m1=m1.rms( m1_g.g( m1_lp.lp( m_in,f1 ))) *trim17;

m2=m2.rms(m2_.hp( m2_g.g( m2_bp.bp( m_in,f2,q2 )),f2 )) *trim18;

m3=m3.rms(m3_.hp( m3_g.g( m3_bp.bp( m_in,f3,q3 )),f3 )) *trim19;

m4=m4.rms(m4_.hp( m4_g.g( m4_bp.bp( m_in,f4,q4 )),f4 )) *trim20;

m5=m5.rms(m5_.hp( m5_g.g( m5_bp.bp( m_in,f5,q5 )),f5 )) *trim21;

m6=m6.rms(m6_.hp( m6_g.g( m6_bp.bp( m_in,f6,q6 )),f6 )) *trim22;

m7=m7.rms(m7_.hp( m7_g.g( m7_bp.bp( m_in,f7,q7 )),f7 )) *trim23;

m8=m8.rms(m8_.hp( m8_g.g( m8_bp.bp( m_in,f8,q8 )),f8 )) *trim24;

m9=m9.rms(m9_.hp( m9_g.g( m9_bp.bp( m_in,f9,q9 )),f9 )) *trim25;

m10=m10.rms(m10_.hp( m10_g.g( m10_bp.bp( m_in,f10,q10 )),f10 )) *trim26;

m11=m11.rms(m11_.hp( m11_g.g( m11_bp.bp( m_in,f11,q11 )),f11 )) *trim27;

m12=m12.rms(m12_.hp( m12_g.g( m12_bp.bp( m_in,f12,q12 )),f12 )) *trim28;

m13=m13.rms(m13_.hp( m13_g.g( m13_bp.bp( m_in,f13,q13 )),f13 )) *trim29;

m14=m14.rms(m14_.hp( m14_g.g( m14_bp.bp( m_in,f14,q14 )),f14 )) *trim30;

m15=m15.rms(m15_.hp( m15_g.g( m15_bp.bp( m_in,f15,q15 )),f15 )) *trim31;

m16=m16.rms(m16_.hp( m16_g.g( m16_bp.bp( m_in,f16,q16 )),f16 )) *trim32;

// Modulation Block

c1*=m1; c2*=m2; c3*=m3; c4*=m4;

c5*=m5; c6*=m6; c7*=m7; c8*=m8;

c9*=m9; c10*=m10; c11*=m11; c12*=m12;

c13*=m13; c14*=m14; c15*=m15; c16*=m16;

//the final summing and amp section






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Guest skibby

that code will be out of date, just check the reaper forum js thread for updates i reckon.

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Huge fan of the original Bode here, will there be a vst version?

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wicked. I need a good software vocoder. gonna have to check this out!

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Guest skibby

still missing:


noise generator
better sibilance filter+saturation


much to come.

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Guest wyvern

Very cool. I was looking into timbre.js, which wraps Web Audio API, for browser embedded synth. Those are fun to play with.

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Guest skibby

as it stands, this plugin is very expensive CPU wise. just like real life, since a real Bode would also be expensive. even the gear required to make one would cost a lot.


a good thing to do would is devirtualise this down to a pcb and make it into hardware someday.


before then, some optimisation will imminent itself

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is there a vst version?

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Guest skibby

reajs has a third party hostable vst version, but only for pc right now.

comes bundled at http://www.reaper.fm/reaplugs/


otherwise, reaper comes with reajs and runs on all platforms.

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Impressive! How long did this take?


I'm starting research on a web midi thing. This is amazing. :D

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Guest skibby

took 3 or 4 days to implement so far, but it took ages to both understand how actually simple it is and get around to doing it.

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