Table of Contents:

What is Panning?

Panning is the process of using left and right channels separately.

Panning Math

Assuming we have a value P0 which represents the value of the panning knob (-1 to 1) we can get coeficients that act as a gain value for each channel.

$$ LeftCoeficient = 0.5 - (P_0/2) $$

$$ RightCoeficient = 0.5 + (P_0/2) $$

See Desmos example below for visual:

https://www.desmos.com/calculator/ieqrzoiqm8

Implementing in Code

We can use the example from last section to build a panning function.

float[] PanningCalc( float Panning ) {

	Panning = (Panning * 2.f) - 1.f; //change 1 - 0 to -1 - 1

	float LeftVal = 0.5f - (Panning / 2);
	float RightVal = 0.5f + (Panning / 2);
	
	float[] Values[2] = [LeftVal, RightVal];
	return Values;
}

And then in our processing we can use this to add gain to our samples accordingly.

Vst::Sample32* LeftIn = data.inputs[0].channelBuffers32[0];
Vst::Sample32* RightIn = data.inputs[0].channelBuffers32[1];

Vst::Sample32* LeftOut = data.outputs[0].channelBuffers32[0];
Vst::Sample32* RightOut = data.outputs[0].channelBuffers32[1];

for (int i = 0; i < data.numSamples; i++) {

	float[] PanningValues = PanningCalc( mPan );
	LeftOut[i] = LeftIn[i] * PanningValues[0];
	RightOut[i] = RightIn[i] * PanningValues[1];

}