Is it safe to put the result of AudioProcessorValueTreeState::getParameter out of the processBlock method?

[zsliu98]

@rp1

Not sure I understand. In the context of a standalone app (not in the plugin context, where I can rely on the host automation), my goal is to be able to account for incoming MIDI CC at their planned time.

Ahh, you want to use MIDI to automate some parameters in Standalone. Unfortunately, I am not familiar with this usage context. However, if you look at the source code, setValueNotifyingHost would introduce a CriticalSection, which looks suspicious to me. Perhaps you can use a timer to check if there is any parameter to update?

@rp1

Some GUI slider (configured as juce::AudioProcessorValueTreeState::SliderAttachment) can also affect the same parameters.

You may want to go through the following post before using SliderAttachment. If you call setValueNotifyingHost in the audio thread, then the real-time safety problem from SliderAttachment might be concerning,

Is MessageManager::callAsync() real-time safe?

So, I have been using callAsync in most situations where something has to be done on the message thread instead of the audio thread, eg when parameterChanged is called from the audio thread. I have had issue so far and I find this method much simpler and practical (although it does not coalesce) than setting an atomic bool and polling it with a timer, or using AsyncUpdater which is not real-time safe anyway, it appears). It is safe (enough) for real-time use though? Should I replace it with r…