Moving SIZE clears the reverb buffer or resets it causing artifacts?

[DavidsonAudioMulti]

Moving SIZE clears the reverb buffer or resets it causing artifacts? When I move the size control it resets any current reverb, can we make to where one can adjust the SIZE in realtime?

Thanks

[lorenzje]

The issue with the SIZE parameter resetting the reverb buffer lies in how it interacts with the internal processing state. Currently, adjusting SIZE likely triggers a reinitialization of internal structures or buffers, causing the reverb to restart and resulting in audible artifacts.

Solution
To make the SIZE parameter adjustable in real-time without artifacts:

Gradual Transition: Interpolate the change in the SIZE parameter over multiple processing frames, allowing the system to adjust smoothly without disrupting the buffer.
Non-Destructive Buffer Handling: Avoid clearing or reinitializing the entire reverb buffer when SIZE changes. Instead, apply the new SIZE value adaptively.
Conditional Reinitialization: Reinitialize only if a drastic change in SIZE occurs (e.g., a large jump), but use fading or crossfading techniques to reduce artifacts.
Implementation
Update the handling of the SIZE parameter in the MVerb processing code:

Interpolate Parameter Changes: Modify the setParameter method to smooth changes in SIZE. For instance:

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void MVerb::setParameter(int index, float value) {
if (index == SIZE) {
float previousSize = currentSize;
targetSize = value;
sizeTransitionStep = (targetSize - previousSize) / transitionFrames;
}
parameters[index] = value;
}
Apply Changes Gradually: In the process method, gradually adjust the SIZE value per frame:

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void MVerb::process(float** inputs, float** outputs, int sampleFrames) {
for (int i = 0; i < sampleFrames; ++i) {
// Smoothly transition SIZE
if (std::abs(targetSize - currentSize) > 0.0001f) {
currentSize += sizeTransitionStep;
if ((sizeTransitionStep > 0 && currentSize >= targetSize) ||
(sizeTransitionStep < 0 && currentSize <= targetSize)) {
currentSize = targetSize;
}
updateSize(currentSize);
}
// Process audio
processSample(inputs, outputs, i);
}
}
Update the Size Gradually: Implement updateSize(float size) to adjust only the necessary internal state without resetting the entire buffer.

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void MVerb::updateSize(float size) {
// Update size-dependent parameters without clearing the buffer
roomSize = size;
adjustDelayLines(size);
}
By implementing this interpolation and selective updating mechanism, you can allow real-time SIZE adjustments without introducing disruptive artifacts.

[lorenzje]

Hi! I have forked this code and fixed the issue: Smooth Transitions for SIZE Parameter:

Introduced a targetSize variable in MVerb to allow gradual transitions for the SIZE parameter instead of abrupt changes.
Updated the process method in MVerb to interpolate SizeSmooth toward targetSize over multiple audio frames.
Buffer Clearing Avoidance:

Modified MVerb's updateDelayLinesAndFilters to adjust delay line lengths and indices dynamically without clearing buffers. This prevents audible artifacts like clicks or pops during real-time adjustments.
Delegation in VstPlugin:

Ensured that setParameter and getParameter in VstPlugin correctly delegate changes to the updated MVerb class.
Testing and Compatibility:

Verified that no changes were required in VstPlugin.h beyond ensuring compatibility with the updated MVerb.

Check my fork if you wanna see ! :)