ProcessorChain not affecting audio

1

I decided to try out the ProcessorChain in juce::dsp but am having trouble getting it wired up. Currently my VST passes the signal completely unchanged and I’m not sure why.

In Processor.h I have:

    juce::dsp::ProcessorChain<juce::dsp::IIR::Filter<float>, Gain> filter_stage_0;

In prepareToPlay I have:

    juce::dsp::ProcessSpec spec;
    spec.sampleRate = host_sample_rate;
    spec.maximumBlockSize = juce::uint32(samplesPerBlock);
    spec.numChannels = juce::uint32(getTotalNumOutputChannels());

    filter_stage_0.prepare(spec);
    filter_stage_0.reset();

In parameterChanged I get some parameters from an AudioProcessorValueTreeState and set the coefficients:

    low_cutoff_1 = *tree.getRawParameterValue("low_cutoff_1");
    low_q_1 = *tree.getRawParameterValue("low_q_1");
    gain_1 = *tree.getRawParameterValue("gain_1");
    newCoefficients = juce::dsp::IIR::Coefficients<float>::makeHighPass(
        host_sample_rate, low_cutoff_1, low_q_1);
    filter_stage_0.get<0>().coefficients = newCoefficients;
    filter_stage_0.get<1>().setGainLinear(gain_1);

In processBlock I have:

    juce::dsp::ProcessContextReplacing<float> context(
        juce::dsp::AudioBlock<float>(buffer)
    );
    filter_stage_0.process(context);

When the VST is loaded, changing the cutoff or gain does nothing – the audio is being passed through completely unchanged.

I guess I’m just missing a step but looking through the examples / tutorials I can find online hasn’t clarified it for me.

2

Coefficients is a ptr, so you need to dereference here:

*filter_stage_0.get<0>().coefficients = *newCoefficients;
3

@daniel Good spot, thanks – I made the change. It hasn’t altered the behaviour though.