From the original SynthMaker forum (2004–2014), with its members’ names and dates.
Eska ·
This is a Cheap-pseudo-sinusoidal-lfo, basic formula grabbed from the musicdsp.org by fumminger:
polyin Freq;//in Hz polyin Level; polyin Samplerate; polyout Out;
float y; float x; float stp; float t; stage(0) { t=128/Samplerate; Freq=Freq*2; } stage(1) { hop(128) { stp = Freq * t ; x=x+stp; // Compute 2*(x^2-1.0)^2-1.0 y=((x*x-1.0)*(x*x-1.0)*-2.0)+1.0; x=x-(x>=1.0)&2.0;
Out = y *Level; } }
oddson ·
Welcome to the forum... 🙂
Freq=Freq*2;
Won't work. SM won't allow you to write to input variables. (At least last time I tried to get away with it. Let me know if I'm mistaken.)
Declare a new variable first and then store Freq*2 to it.
Eska ·
Howdy oddson. Freq=Freq*2; Works fine here.
stefan ·
It works sometimes, and others not. Because it's a bit dangerous. What you actually end up doing is changing the external value, which might lead to weird stuff 🙂
Eska ·
I see. To put this calculation in stage(0) was stupid anyway. Here is the corrected version:
polyin Freq;//in Hz polyin Level; polyin Samplerate; polyout Out;
float y; float x; float stp; float t; stage(0) { t=128/Samplerate; } stage(1) { hop(128) { stp = Freq*2.0 * t ; x=x+stp; // Compute 2*(x^2-1.0)^2-1.0 y=((x*x-1.0)*(x*x-1.0)*-2.0)+1.0; x=x-(x>=1.0)&2.0;
Out = (y-1.0) *Level; } }
Tom7777 ·
Welcome 🙂
Eska ·
Hi Tom777. One last change, I hope. Removed the DC-offset and added sin to ~saw modulation:
polyin Freq;//in Hz polyin Level; polyin Samplerate; polyout Out; polyin form;//0to1 float y; float x; float stp; float t; stage(0) { t=128/Samplerate; } stage(1) { hop(128) { stp = Freq*2.0 * t ; x=x+stp; // Compute 2*(x^2-1.0)^2-1.0 y=((x*x-1.0)*(x*x-1.0)*-2.0)+1.0; x=x-(x>=1.0)&(2.0 - form);
Out = y *Level; } }
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