SmoothedValue overshoot issue

Audio Plugins
1

Not sure if this is a bug or more of a known issue, but I don’t see it mentioned anywhere:

SmoothedValue in linear smoothing mode returns values from getNextValue() that overshoot the value given in setTargetValue().

To see this, paste the following into juce_SmoothedValue.h at line 308:

    if (step > 0 && this->currentValue > this->target)
        DBG ("SmoothedValue overshoot warning: currentValue went over target. "
             + String (this->currentValue, 7) + " > " + String (this->target, 7));
    
    if (step < 0 && this->currentValue < this->target)
        DBG ("SmoothedValue overshoot warning: currentValue went under target. "
             + String (this->currentValue, 7) + " < " + String (this->target, 7));

Then observe the DBG output as you rapidly move a Slider attached to a Parameter (this would be in the context of what I’d consider typical usage - where setTargetValue is called once at the top of each processBlock, and then getNextValue is called in the per-sample loop therein.)

In practice, this can be especially problematic at the far limits of Slider movement. It results in SmoothedValue returning values that exceed the Parameter’s given range.

1 Like
2

This is probably due to a rounding error… I had been using SmoothedValue templated for float (since that’s what AudioProcessorValueTreeState gives). I tried changing to SmoothedValue templated for double, and that seems to stop the overshoot.