AudioProcessor::setLatencySamples() disables automation in Ableton (vst & au)

[ttg]

I’ve ended up adding this on Sound Radix branch.

Add flag to suggest context of change for: AudioProcessor::updateHost() , AudioProcessorListener::audioProcessorChanged().

Would be nice if JUCE team could do similar on JUCE6.
Due to Ableton being picky, this adds ability to set explicit ‘intention’ of change.

Bonus: you can update preset name for deprecated VST2

audioMasterUpdateDisplay should be called on the UI thread

audioMasterUpdateDisplay should be called on the UI thread. Or else Ableton Live ignores it and won’t update the GUI.

[jimc]

Guys - can someone actually fix this in the main repo

[ttg]

btw, our fix works well

I did miss the hosting side so some audioProcessorChanged needed to be add to plug-in hosting and JUCE demo code. but our QA is happy and it’s nice being able to be explicit for what has changed.

[cgleo]

We are also very much interested in a fix on the JUCE master!

[jimc]

Yes - please fix this. I can cross something off my JIRA if you do without patching JUCE again.

And as we all know, closing JIRA tickets saves kittens from dying.

[zac]

Yeah we’ve observed this too. An easy fix would be great without needing to use sr’s branch.

[reuk]

If anything, Ed’s tab number has only increased in the last few months, so I’ve gone ahead and merged a fix. Thanks @ttg for posting your patch, I ended up going with a similar approach.

AudioProcessor: Update listener callback with change details

[cgleo]

First of all, thanks reuk!

But I just discovered that the fix does not send audioMasterIOChanged to the host when details.latencyChanged == true. This way, Ableton Live (and probably other hosts) will completely ignore the changed latency! VST specs require a plugin to send audioMasterIOChanged when latency changes (there is a comment on the ioChanged() member function in AudioEffectX.h in the original VST2.4 SDK).
Surprisingly, its actually audioMasterUpdateDisplay that disables automations in Ableton, so the best (still sub-optimal) solution would be to omit that when only latency changed.

This fix made it kind of worse, as VST plugins are now entirely unable to change their latency!
(Haven’t yet checked AU and other formats.)

I’d say, HostChangeUpdater should keep an atomic flag of what changed, and evaluate that in the update routine. As in the Sound Radix patch.

[reuk]

Thanks for reporting. I’ve pushed a fix for this issue here:

VST Client: Ensure audioMasterIOChanged is sent when latency is updated

Please let us know if you encounter any further problems.