Cubase: VST3: processBlock: stops getting called after 12s of silence


I have an effect plugin and a tester of mine has reported an issue with VST3 whose tail gets cut off after about 12s of no actual signal passing through.

I am setting the tail to max:

double PluginProcessor::getTailLengthSeconds() const
	return std::numeric_limits<double>::max ();

The VST2 version of this same plugin doesn’t cut off like that.

The issue is reproducible in any version of Cubase 9.5.

How do you deal with this?

I see that FabFilter have fixed precisely this issue in the past

Pro-R: Fixed a bug in the VST3 plug-in that caused long reverb tails to be cut off after 10 seconds after the input became silent.

Anyone from FabFilter in da house?

Is this right?

Doesn’t this result in Vst::kNoTail pretty much… all the time?

I debugged it with Cubase 9.5 and it always returns kNoTail, beacuse there always is sampleRate > 0.0.

@jules Shouldn’t this be like that?

Steinberg::uint32 PLUGIN_API getTailSamples() override
    auto tailLengthSeconds = getPluginInstance().getTailLengthSeconds();

    if (tailLengthSeconds <= 0.0 || processSetup.sampleRate <= 0.0)
        return Vst::kNoTail;

    return (Steinberg::uint32) roundToIntAccurate (tailLengthSeconds * processSetup.sampleRate);

I missed to report that changing the condition didn’t make a difference in Cubase specifically, but I am not sure how other hosts would react. Very weird that no one has hit this for 4 years…


BTW, in Cubase this can be disabled: Preferences/VST/Plug-Ins and uncheck “Suspend VST3 plug-in processing when no audio signal are received”. But if the implementation for tail is incorrect and the host doesn’t allow it, there is still an issue.

There seems to be an alternative to setting the tail - adding kFxGenerator as another subcategory.

How do I add 2 categories within JucePlugin_Vst3Category?

The VST3 docs says:

can be more than one, logically added by the OR operator

#define JucePlugin_Vst3Category "Fx|Analyzer|Delay|Distortion|Dynamics|Generator"

Keep the leading “Fx” and add categories like this.

Mind you - this isn’t foolproof. Cubase will only list your plug-in in the first category you supply. Other hosts, such as REAPER, will list your plug-in in multiple places.