Gain to db values

[Zander9719]

Hi,

I’m in the process of trying to figure out the implementation for converting gain values from the AudioParameterFloat definition in the constructor into db and % for the UI in the editor.

    addParameter(mDelayTimeParameter = new AudioParameterFloat("delatime",
                                                               "Delay Time",
                                                                0.0f,
                                                                0.15f,
                                                                0.02f));
    
    
    addParameter(mFeedbackParameter  = new AudioParameterFloat("feedback",
                                                              "Feedback",
                                                               0.0f,
                                                               0.98f,
                                                               0.1));
    
    addParameter(mDryWetParameter    = new AudioParameterFloat("drywet",
                                                              "Dry / Wet",
                                                               0.0f,
                                                               1.0f,
                                                               0.5f));
    
    addParameter(mSaturationlevelParameter  = new AudioParameterFloat("saturation",
                                                                     "Saturation",
                                                                      1.0f,
                                                                      6.0f,
                                                                      1.5));
    
    addParameter(mDelayOutputLevelParameter = new AudioParameterFloat("output",
                                                                      "Output Level",
                                                                      0.0f,
                                                                      1.0f,
                                                                      0.5f));
    
    //    static float Decibels::gainToDecibels	(float	gain,
    //                                             float minusInfinityDb = float (defaultMinusInfinitydB)
    //                                             );

I understand the conversion between gain values:
0-1 to db 20*log(x) = db
0-1 gain * 100 = %

However, I’m not sure where to implement this to allow the process block to deal with gain values and the UI to show db values

I attempted to alter the slider.Setvalue method in the editor but these just defaulted back to the values set in the constructor

    ///////////////////////////////////////////////////////
    //////////// SATURATION LEVEL SLIDER /////////////////
    
    AudioParameterFloat* mSaturationlevelParameter = (AudioParameterFloat*)params.getUnchecked(3);
    
    SaturationlevelSlider.setSliderStyle(Slider::SliderStyle::RotaryHorizontalVerticalDrag);
    SaturationlevelSlider.setBounds(400,100,200,80);
    SaturationlevelSlider.setRange(mSaturationlevelParameter->range.start, mSaturationlevelParameter->range.end);
    SaturationlevelSlider.setValue(20*log(*mSaturationlevelParameter)); <--- if only it were that simple
    //  mDelayTimeSlider.addListener(this);
    SaturationlevelSlider.setTextValueSuffix("db");
    addAndMakeVisible(SaturationlevelSlider);
    
    SaturationlevelSlider.onValueChange = [this, mSaturationlevelParameter]
    { *mSaturationlevelParameter = SaturationlevelSlider.getValue(); };
    
    SaturationlevelSlider.onDragStart = [mSaturationlevelParameter]
    { mSaturationlevelParameter->beginChangeGesture(); };
    
    SaturationlevelSlider.onDragEnd = [mSaturationlevelParameter]
    { mSaturationlevelParameter->endChangeGesture(); };
    
    addAndMakeVisible(SaturationlevelSlider);
    SaturationlevelLabel.setText("Saturation", dontSendNotification);
    SaturationlevelLabel.attachToComponent(&SaturationlevelSlider, true);

I have read through the forum posts on the topic, but my understanding is not yet such that I can make sense of them.

I have read these sources:

https://docs.juce.com/master/classDecibels.html#aa8114cb97adb33d7723e8a5bc6f67c18

Using applyGain to add additional gain, rather than set the gain?

That is the difference between gain and level… Gain is a factor, that multiplies the values. If you express a gain in level, it is a logarithmic value and is adding to the existing levels. Applying a gain of 2 (factor) will add 6 dB to the level. Applying factor 4 is adding 12 dB and applying factor 8 is adding 18 dB. HTH

Modify the display value of an AudioParameterFloat

Exactly, those are the ones for the Slider, and for the host you use the lambdas. I created a recyclable one in my latest project, have a look at TextFormattedSlider: And the lambdas for that: HTH (I have to renew my apple dev cert, then it will be available for download)

Match editor labels to AudioProcessorValueTreeState parameters

That is exactly the topic of the thread I linked above, the SliderAttachments don’t get access to the AudioParameter’s lambdas, so you have to set them by copying the lambda from the parameter into your slider’s label. I created a little convenience Slider-subclass, where I can specify the label cases I came across, to be a little less likely to copy code, hope that helps: class TextFormattedSlider : public Slider { public: enum { RawNumber = 0, LevelDB, GainDB, …

but I need a noob run through if anyone would care to enlighten me!

Thanks,

Alex

[xenakios]

Maybe just define the parameter to deal with the Decibels (instead of the 0.0-1.0 range) and convert to a gain factor in your audio processing. Juce by the way has the Decibels class which has static methods to deal with the gain to decibels and decibels to gain conversions.

[Zander9719]

Duh! Thank you!

I have a terrible habit of overcomplicating things.

All the best,

Al