CODEWITHSUNDEEP
c++audiosignal-processingconvolutionjuce
willfo
willfo

Reputation: 249

Wet/dry control in Juce convolution reverb plugin

I am creating a convolution reverb plugin for university and I have managed to get a simple plugin working, where the output is the input through an impulse response. I am wondering how I can alter the code to make a wet/dry parameter.

I have added a "blend" parameter for this: 

const float defaultBlend = 0.5f;
addParameter(blendParam = new FloatParameter (defaultBlend, "Blend"));

the convolver is then initialised:

convolver.init (512, buffer.getReadPointer(0), buffer.getNumSamples());

and processed here:

 for (int channel = 0; channel < getNumInputChannels(); ++channel)
    {
        float* channelData = buffer.getWritePointer (channel);
        const float* inputData = buffer.getReadPointer(channel);

        for (int i = 0; i < buffer.getNumSamples(); ++i)
            channelData[i] = inputData[i] * level / 20;

        //convolver stuff
        convolver.process (inputData, channelData, buffer.getNumSamples());

    }

any ideas?

Upvotes: 2

Views: 1854

Answers (1)

OMGtechy
OMGtechy

Reputation: 8220

Thinking about your problem, it appears that you are looking for the following properties:

  1. Given a blendParam of 0.0f, just pass on the audio unchanged.
  2. Given a blendParam of 1.0f, process the audio to its maximum capacity.
  3. Given a blendParam of 0.5f, mix half unprocessed audio with processed audio.

I advise you write some unit tests for the above (and more) before proceeding.

The following code appears to satisfy these properties:

channelData[i] = level * (inputData[i] * (1.0f - blendValue) + convolvedData[i] * blendValue);
  • convolvedData is your "fully processed" data.
  • blendValue is the cached value of blendParam.getValue()

You can obtain convolvedData by calling convolver.process as you currently do, with a separate array called convolvedData as your output parameter.

Note that this doesn't account for clamping the resulting number into the range [-1.0f, 1.0f], and there is likely a more efficient way of doing this, but it's a starting point for you.

Upvotes: 1

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