Tonal Balance

Christoph Hart

@Fortune Well that's a GPL licensed code so you won't be able to use it in a proprietary project.

Fortune

@Fortune Well that's a GPL licensed code so you won't be able to use it in a proprietary project.

The soft knee equation is not licensed to anyone, it is universal :) https://dsp.stackexchange.com/questions/73619/how-to-derive-equation-for-second-order-interpolation-of-soft-knee-cutoff-in-a-c

I just gave this example to show how it can be done. You can modify or duplicate the juice compressor or simple compressor with the equation.

The standard hard knee comp equation is this (I believe Hise Simple Compressor and jcompressor uses this):
Screen Shot 2022-08-10 at 08.38.21.png

But the soft knee equation is that:

Screen Shot 2022-08-10 at 08.38.49.png

Soft knee sounds musical and more natural, where hard knee sounds digital and pretty bad on most of the professional mix cases.

alt text

Christoph Hart

@Fortune If you're that deep into the subject, you should be able to transform this into C++ or SNEX code, it's basically just rewriting the formula so that the computer understands it.

template <int NV> struct soft_knee_mod
{
	SNEX_NODE(soft_knee_mod);
	
	double W = 0.2;
	double T = 0.5;
	double R = 4.0;
	double Xg = 1.0;
	
	/** If you define this method, it will create a mod dragger
		that will send out the value you set the v parameter reference to.
		
		This function takes the parameters and applies the formula for the
		soft-knee curve...
	*/
	bool handleModulation(double& v)
	{
		if(Xg == 0.0)
		{
			v = 1.0;
			return true;
		}

		if(T == 1.0 && W == 0.0)
		{
			v = 1.0;
			return true;
		}

		if(2.0 * (Xg - T) < (-1.0 * W))
		{
			v = Xg;
		}
		else if (2.0 * Math.abs(Xg - T) <= W)
		{
			const double v1 = (1.0 / R - 1.0);
			const double v2 = (Xg - T + W * 0.5);

			v = Xg + v1 * v2 * v2 / (2.0 * W);
		}
		else
		{
			v = T + (Xg - T) / R;
		}
		
		v = Math.range(v / Xg, 0.0, 1.0);
	
		return true;
	}
	
	/** You need to add 4 Parameters:
	
		- Input
		- Threshhold
		- Ratio
		- Knee Width
		
		Then connect the Input knob to the mod output
		of the envelope follower and connect the mod output
		of this node to the gain or mul node that attenuates
		the signal.
	*/
	template <int P> void setParameter(double v)
	{
		if(P == 0) // Input value
			Xg = v;
		if(P == 1) // Threshhold
			T = Math.range(v, 0.0, 1.0);
		if(P == 2) // Ratio
			R = Math.range(v, 1.0, 32.0);
		if(P == 3) // Knee Width
			W = Math.range(v, 0.0, 1.0);
	}
	
	void handleHiseEvent(HiseEvent& e){}
	void setExternalData(const ExternalData& d, int index){}
	void prepare(PrepareSpecs ps){}
	void reset(){}
	template <typename ProcessDataType> void process(ProcessDataType& data){}
	template <int C> void processFrame(span<float, C>& data){}	
};

At the moment it's not possible to share snippets with SNEX nodes, so you have to paste this in manually.

Christoph Hart

And here's the XML for the network. Copy this into a file called softknee_comp.xml

<?xml version="1.0" encoding="UTF-8"?>

<Network ID="softknee_comp" Version="0.0.0" AllowCompilation="1">
  <Node FactoryPath="container.chain" ID="softknee_comp" Bypassed="0"
        ShowParameters="1">
    <Nodes>
      <Node ID="frame2_block" FactoryPath="container.frame2_block" Bypassed="0">
        <Nodes>
          <Node ID="converter" FactoryPath="control.converter" Bypassed="0">
            <Properties>
              <Property ID="Mode" Value="db2Gain"/>
            </Properties>
            <ModulationTargets>
              <Connection NodeId="snex_node" ParameterId="Threshold"/>
            </ModulationTargets>
            <Parameters>
              <Parameter MinValue="-100.0" MaxValue="0.0" StepSize="0.1" SkewFactor="5.422270979580217"
                         ID="Value" Automated="1"/>
            </Parameters>
          </Node>
          <Node ID="envelope_follower" FactoryPath="dynamics.envelope_follower"
                Bypassed="0">
            <ModulationTargets>
              <Connection NodeId="snex_node" ParameterId="Input"/>
            </ModulationTargets>
            <ComplexData>
              <DisplayBuffers>
                <DisplayBuffer Index="-1"/>
              </DisplayBuffers>
            </ComplexData>
            <Parameters>
              <Parameter MinValue="0.0" MaxValue="1000.0" StepSize="0.1000000014901161"
                         SkewFactor="0.2313782125711441" ID="Attack" Automated="1"/>
              <Parameter MinValue="0.0" MaxValue="1000.0" StepSize="0.1000000014901161"
                         SkewFactor="0.2313782125711441" ID="Release" Automated="1"/>
              <Parameter MinValue="0.0" MaxValue="1.0" ID="ProcessSignal" Value="0.0"/>
            </Parameters>
          </Node>
          <Node ID="snex_node" FactoryPath="core.snex_node" Bypassed="0">
            <Properties>
              <Property ID="ClassId" Value="soft_knee_mod"/>
            </Properties>
            <ModulationTargets>
              <Connection NodeId="mul" ParameterId="Value"/>
            </ModulationTargets>
            <ComplexData>
              <Tables/>
              <SliderPacks/>
              <AudioFiles/>
              <Filters/>
              <DisplayBuffers/>
            </ComplexData>
            <Parameters>
              <Parameter MinValue="0.0" MaxValue="1.0" ID="Input" Automated="1"/>
              <Parameter MinValue="0.0" MaxValue="1.0" ID="Threshold" Automated="1"/>
              <Parameter MinValue="1.0" MaxValue="32.0" ID="Ratio" Automated="1"/>
              <Parameter MinValue="0.0" MaxValue="1.0" ID="KneeWidth" Automated="1"/>
            </Parameters>
          </Node>
          <Node ID="mul" FactoryPath="math.mul" Bypassed="0">
            <Parameters>
              <Parameter MinValue="0.0" MaxValue="1.0" ID="Value" Automated="1"/>
            </Parameters>
          </Node>
        </Nodes>
        <Parameters/>
        <Properties>
          <Property ID="IsVertical" Value="0"/>
        </Properties>
      </Node>
    </Nodes>
    <Parameters>
      <Parameter ID="Threshold" MinValue="-100.0" MaxValue="0.0" StepSize="0.1"
                 SkewFactor="5.422270979580217" Value="0.0">
        <Connections>
          <Connection NodeId="converter" ParameterId="Value"/>
        </Connections>
      </Parameter>
      <Parameter ID="Ratio" MinValue="1.0" MaxValue="32.0" Value="1.0">
        <Connections>
          <Connection NodeId="snex_node" ParameterId="Ratio"/>
        </Connections>
      </Parameter>
      <Parameter ID="Attack" MinValue="0.0" MaxValue="1000.0" StepSize="0.1000000014901161"
                 SkewFactor="0.2313782125711441" Value="13.60000020265579">
        <Connections>
          <Connection NodeId="envelope_follower" ParameterId="Attack"/>
        </Connections>
      </Parameter>
      <Parameter ID="Release" MinValue="0.0" MaxValue="1000.0" StepSize="0.1000000014901161"
                 SkewFactor="0.2313782125711441" Value="28.80000042915344">
        <Connections>
          <Connection NodeId="envelope_follower" ParameterId="Release"/>
        </Connections>
      </Parameter>
      <Parameter ID="KneeWidth" MinValue="0.0" MaxValue="1.0" Value="0.1531573486328126">
        <Connections>
          <Connection NodeId="snex_node" ParameterId="KneeWidth"/>
        </Connections>
      </Parameter>
    </Parameters>
  </Node>
</Network>

I've also updated the SNEX code - I had to convert the output to a gain ratio and add some edge case handlings, but if you save this code as soft_knee_mod it should work.

Christoph Hart

Oh and BTW: no idea if it sounds good, I did this on my laptop without headphones. The curve looks alright though, but if you increase the knee width it will start acting like a noise gate (I think the knee width has to be relative to the threshold or it will nudge small values to zero real quick).

Fortune

@Christoph-Hart Thank you so much mate, I really appreciate your help!

I know the theory well but don't have a deep C++ know-how as even 1/1000 of you. I woke up and saw your message and I've been on this for 3 hours with tons of tests, first code wasn't working well but your updated code sounds great!

Below is the dynamics test on the PluginDoctor. Like you said the Knee Width depends on the Threshold value (maybe I need to modify it with a pma node to fix the value), but if it is set, you can get awesome curves and tones.

Also even I put all of them into a frame2 block, the compiled network is incredibly fast and cpu effective! I've never seen this kind of thing, congrats Christoph, that is showing that you're a real Genius.

Maybe you can add this to the templates.

A Former User

@Christoph-Hart @Fortune

So Sweet! Thank you so much guys, it sounds GREAT.

A Former User

@Christoph-Hart I've been waiting this for a long time, thank you very much!

Christoph Hart

@Fortune You don't need to split the signal, if ProcessSignal is deactivated, it can all flow just through the default chain container.

Fortune

@Christoph-Hart The ProcessSignal of the Envelope follower, right? Ok Thank you it is good to know that.

One last thing, is it possible to display the gain reduction amount (in dB) with a knob?

I would follow this guide but don't know how to get the External Buffer from SNEX: https://forum.hise.audio/topic/6324/scriptnode-compressor-gain-reduction/2

Christoph Hart

@Fortune just send the mod output of the snex node to an add node in a modchain, put a peak node behind it and use that instead.

Fortune

@Christoph-Hart I will do that, Thank you!

Christoph Hart

Oh and if you want to make the knee width relative to the threshold, don't use a pma node, but just this line in the beginning of the handleModulation() method:

const double Wt = W * T * 2.0;

And then use this value in the handleModulation method instead of W. The 2.0 makes the knee a bit more noticeable but you can play around with values.

Fortune

@Christoph-Hart

Yesss, that's it!!! Knee Width can be adjustable sensitively, both hard and soft knee settings are available in one compressor

Thank you so much for your help mate!

By the way, I set the Release time of the envelope 10000 ms, it has a very smooth sound now :)

NOTE: Yellow flicking vertical slider is the reduction meter.

!

orange

@Christoph-Hart @Fortune It's super useful, now the compressor sounds much better. Thank you!

pluginboi

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