Getting AudioProcessorValueTreeState

General JUCE discussion
1

Hey,
I just wanted to make sure I’m not doing something I shouldn’t.
Seems weird to me calling it like this but it’s working

AudioProcessor::processBlock (juce::AudioBuffer<float>& buffer, juce::MidiBuffer& midiMessages)
{

    auto drive = apvts.getRawParameterValue("DRIVE");
    auto range = apvts.getRawParameterValue("RANGE");
    
    float driver = drive->load();
    float ranger = range->load();
   
`//now comes the channal and the buffer loop, just saved you code
        for(int sample = 0; sample < buffer.getNumSamples(); sample ++)
        {

            channelData[sample] *= (driver * ranger); //bla bla

Is there a better/cleaner way of loading the APVTS? and if so what are the disadvantages of my code?

2

No need to be creating variables for the raw parameters in the processBlock(). Make them class members.

auto drive = apvts.getRawParameterValue("DRIVE");
auto range = apvts.getRawParameterValue("RANGE");

Then, you should move your raw parameter variables to prepareToPlay(), or even the constructor for the processor.

1 Like
3

Thanks, not sure on how to pass them from the prepareToPlay(), as I’m just starting with c++,
as I understand it they are already class members of APVTS no?
any guidance would be highly appreciated at this point

BTW I declared them as floats - because otherwise I’m getting an error - Cannot initialize a parameter of type 'float' with an lvalue of type 'std::__1::atomic<float>

4

The best approach is to use the parameter itself as member. They are members of the APVTS, that’s correct. But the getRawParameterValue() and the getParameter() as well do a lookup that is avoidable by having a member variable that is set only once in the constructor.

class MyAudioProcessor : public juce::AudioProcessor
{
    // ...your other code...
private:
    juce::AudioParameterFloat* drive = nullptr;
    juce::AudioParameterFloat* range = nullptr;
};

// in the constructor:
MyAudioProcessor::MyAudioProcessor()
  : // all the stuff
{
    // ... all your other initialisations ...

    drive = dynamic_cast<juce::AudioParameterFloat*>(apvts.getParameter ("DRIVE"));
    jassert (drive);  // if this fires you don't have a parameter of that type with that ID

    range = dynamic_cast<juce::AudioParameterFloat*>(apvts.getParameter ("RANGE"));
    jassert (range);  // if this fires you don't have a parameter of that type with that ID
}

// in processBlock or wherever you need it:

auto driveValue = drive->get();  // returns the current float value
auto rangeValue = range->get();  // returns the current float value

Hope that helps

1 Like
5

Daniel always has good and helpful ideas. So you can study his example.

I was going to illustrate my way of doing it, but I think if you can understand Daniel’s approach you will be able to get things working as you require.

1 Like