Is there any convinient way to change Range of AudioParameterFloat?

Is there any convinient way to change Range of AudioParameterFloat?

I have release time parameter with range defined in the constructor:

std::make_unique<AudioParameterFloat>(ParameterID(RELEASE_ID, 1),
                                      NormalisableRange<float>( RE_MIN,   RE_MAX,   RE_STEP),

But I also have auto release option. And after auto release is engaged I don’t want to turn off release time knob, but change the range of it little bit.

I see NormalisableRange<float> range is public component of AudioParameterFloat. But is it good idea to just call:

AudioParameterFloat*  prm = dynamic_cast<AudioParameterFloat*>(pajParams.getParameter(RELEASE_ID));

if(prm != nullptr)
    prm->range = NormalisableRange<float>(newMin, newMax, newInterval);

For any advice great thanks in advance.
Best Regards

You have two viable solutions:

  1. Let your parameter having a 0~1 range and just change what is displayed to the user. You’ll deal with the normalisation outside your parameter class. This is what I do today when needed.

  2. Changing your parameter range when needed. I successfully used this technique on a commercial plugin I released years ago.

I have a method in the processor that I call when I need to change a parameter’s range. I have my own float parameter class with some customisations:

void MyAudioProcessor::changeParameterRange(AudioProcessorParameter* par, const float start, const float end,
                                                  const float skew, const String& paramUnit, const float defValue)
    My_NewFloatParameter* fp = dynamic_cast<My_NewFloatParameter*>(par);
    fp->changeRange(start, end, skew, paramUnit);

In my custom parameter class I have this method:

void changeRange(const float start, const float end, const float skew, const String& paramUnit)
        paramRange.start = start;
        paramRange.end = end;
        paramRange.skew = skew;
        unitString = paramUnit;

So, when you need to change the parameter you can just call the first method, being sure it needs to be updated:

if(currentState != lastState)
     changeParameterRange(param1, 0.0f, 100.0f, 1.0f, "%", 50.0f);
     lastState = currentState;

In this way you’ll avoid to constantly changing the param range every time the user changes a parameter.

Hope this helps.


1 Like

Hmm… great thanks for such detailed and helpful answer.

But due to 2. solution. I see you are actually do the same as it is in my code. But you don’t create new range as I do. You instead just assigning new values to start, end and skew. I wonder if it makes any difference.

But what is more frustrating I found out issue in juce::Slider when changing the range of attached parram. The scenario looks as following:
When I attach param to Slider and param at it’s current state has narrow range, than when I change the range to be wider the slider still remember old narrow range. And I am not sure what is the best solution for that. Should I reattach param to slider or update range of slider by myself?

At the moment I just make sure that param has wider range when initialising Slider. But it is stupid because when plugin editor is closed, and range of param is narrow, then during opening editor I need to reset range to be wider, attach it to slider and then back range to be narrow. And I am not sure what happen when there are some automations currently changing the param in real time.
Have you managed such issue before?

By the way I also wonder what exactly is in your code the paramRange? Is it juce::NormalisableRange<float> ?
Or something more customised?

Best Regards

I don’t use ranges on my sliders, since almost all of them are filmstrip based. Basically I set them this way:

mySlider->setRange(0.0, 1.0, knobResolution);

where “knobResolution” is usually 1.0/(float)(numFrames-1)

Hmm ok, it seems reasonable.
Great thanks for help.