Apply a waveshaper function

[dannytaurus]

I have a fairly simple waveshaper function, something like this:

left = in1
right = in2
curve = in3 * some formula

out1 = curve * left
out2 = curve * right

There's a bit more to it than that but not much. It just takes L and R inputs and a control parameter then performs a function on each input and sends them to the outputs.

What's the easiest way to implement this?

[aaronventure]

@dannytaurus Scriptnode

Do you have 3 input channels? What is in3?

[orange]

@dannytaurus If you do not have a very complex algorithm, you do not have to process separately for left and right in SNEX.

• Insert a snex_shaper node
• Create a new file and name it "MyNode"
• Add a parameter - this will be the Drive knob
• Paste the code below

template <int NumVoices> struct MyNode
{
	SNEX_NODE(MyNode);
	
	// Parameters
	float Drive = 0.0f;
	
	float getSample(float input)
	{	
	 	input = Math.tanh(10.0f * Drive * input);	
		return input;		
    }
	
	
	// These functions are the glue code that call the function above
	template <typename T> void process(T& data)
	{
		for(auto ch: data)
		{
			for(auto& s: data.toChannelData(ch))
			{
				s = getSample(s);
			}
		}
	}
	template <typename T> void processFrame(T& data)
	{
		for(auto& s: data)
			s = getSample(s);
	}
	void reset()
	{
		
	}
	void prepare(PrepareSpecs ps)
	{
		
	}
	
	void setExternalData(const ExternalData& d, int index)
	{
	}
	template <int P> void setParameter(double v)
	{
		if (P == 0) Drive = (float)v;
	}
};

As you can see, the waveshaper function is:

out = tanh(10 * Drive * in)

In SNEX, we can write it like this:

input = Math.tanh(10.0f * Drive * input);	
return input;

[Christoph Hart]

There's a bit more to it than that but not much. It just takes L and R inputs and a control parameter then performs a function on each input and sends them to the outputs.

If you're using a stateless function with a single parameter, you are exactly within the bounds of the math.expr node which does exactly this (not more and not less).

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