I have a Problem About ProcessorDuplicator FIR Is can't build

Audio Plugins
1

This Code

.h
juce::AudioProcessorValueTreeState::ParameterLayout data();
juce::AudioProcessorValueTreeState plugIn{ *this, nullptr, “Parameter”, data() };

float freq{ 0.0 };
float q{ 0.0 };
float slope{ 12 };

void updateHigh();

private:
juce::dsp::ProcessorDuplicator<juce::dsp::FIR::Filter, juce::dsp::FIR::Coefficients> High;

.cpp
void ToneAudioProcessor::updateHigh()
{
*High.state = *juce::dsp::FilterDesign::designIIRLowpassHighOrderButterworthMethod(freq, getSampleRate(), slope);
}

error

Severity Code Description Project File Line Suppression State Detail Description
Error (active) E0349 no operator * matches these operands Tone_SharedCode C:\Users\BJ\Desktop\Project\JUCE\JUCE\Tone\Source\PluginProcessor.cpp 216 operand types are: * juce::ReferenceCountedArray<juce::dsp::IIR::Coefficients, juce::DummyCriticalSection>

thank you

2

First of all, please surround your code by three backticks like ``` before and after the code block to make the forum render it nicely with code highlighting.

That being said, your problem is that juce::dsp::FilterDesign::designIIRLowpassHighOrderButterworthMethod returns an array of coefficient structs and not a single set of coefficients. The intention of this signature is that this function is intended to parametrize a serial chain of multiple IIR instances and returns coefficients for each of them.

This thread discusses a similar problem and presents a possible solution.