Au parameters not loaded correctly when opening AUM project
Nikolozi
open
Just changing the status of this back to Open for now (as I'm not actively working on it), going to wait for Apple's WWDC conference in June to see if they have improved anything and then look at it again closely.
AcoustiMan
Nikolozi thx for the update
Nikolozi
AcoustiMan A quick update. I spoke with Apple's Core Audio engineer during the WWDC labs. It was a productive discussion, demonstrating the bug and providing him with all the details. They will look into it. I'm hoping they fix it by the time iOS 18 is released. If Apple fixes it that would be ideal because you won't need to rely on AUM and Mela hacks-arounds.
AcoustiMan
Nikolozi thx for the update!
Jon Diercks
Nikolozi - I haven't updated to iOS 18 yet, but any word on whether this got fixed?
Nikolozi
Jon Diercks Are you also experiencing the issue of losing mapping (in iOS 17)?
From my tests, it doesn't look like it's fixed in iOS 18.
I'm not sure if you've used Apple's Feedback Assistant, but it's a terrible interface/system where you are not sure if the message is auto-generated or if an actual Apple engineer is messaging you for more information. Anyway, a month or so ago, I got a message on that bug asking me if I was still experiencing it because it's been a while since the bug I reported (wtf??). They probably think bugs resolve themselves. It made me so angry, especially because you feel like you are interacting with a robot at best and because I spoke with a Core Audio engineer in the Labs explaining the issue. As if nothing had happened. Anyway, I left my email in the reply pleading with them to get in touch with me directly to explain the details. Luckily, someone did, but the engineer is clearly too busy to follow all my instructions to reproduce the bug. Currently, email exchange is like 1 per week, super slow. I'm going to now create a custom AUv3 host and send code to show them the bug (even though it's reproducible with AUM and Logic). At least I have direct contact with an engineer.
This is all just to let you know I take this bug seriously and haven't forgotten about it.
Another problem is I think Mela is the only AUv3 that supports dynamic parameter trees, and this is why no one else has come across this.
If, for whatever reason, Apple can't resolve this, one approach I'm thinking of taking is offering a global 8 meta parameters. Which will simply have a 0% to 100% range, and they will control the performance parameters. Mela's parameter tree will always contain these meta parameters no matter what, and in theory, if you use it to do mapping you will never lose. Would this address your issue?
Nikolozi
Quick update, just got an email back from the Apple engineer. He reproduced the bug in Logic Pro and said would investigate further.
Jon Diercks
Nikolozi, I’m now on iOS 18.1.1 and I don’t think the problem is happening anymore. I just loaded a couple saved AUM sessions with Mela in them and the AUv3 Parameter trees appear to be correct on load.
Nikolozi
in progress
The bug is still happening when loading bigger AUM projects.
Nikolozi
complete
Fixed in Mela 4.2 and AUM 1.4.5. If the issue is still happening, please leave a comment and I'll reopen it.
Nikolozi
AcoustiMan a quick update, looks like there's a bug in Core Audio API where hosts don't get notified about the parameter tree changes on plug-in state load.
I worked with the AUM developer and both Mela and AUM will have a workaround for this bug in their respective next update. You will be able to see the correct parameter list and mapping settings shouldn't be lost.
I will also file a detailed bug report to Apple, so hopefully, they can fix this.
AcoustiMan
Nikolozi: thx for the update. I appreciate that!
Nikolozi
AcoustiMan: If you have access to AUM beta, the fix is in AUM 1.4.5 (build 317).
AcoustiMan
Nikolozi:👍
Nikolozi
in progress
Nikolozi
under review
Nikolozi
The problem is hosts sometimes aren't properly observing for AUParameterTree object changes. I'll see if I can improve this from my side, and I'll also get in touch with Jonatan (AUM dev) to see if we can investigate it together.
AcoustiMan
Nikolozi: 👍
AcoustiMan
Nikolozi: in the changelog of 4.2 you mention an added workaround. Can you explain where to find it in 4.2?
Nikolozi
AcoustiMan: you don’t need to do anything it should just work. The workaround is in the code.
Also, you’ll need AUM 1.4.5 (which is still in beta I think) for your AUM session to correctly recall MIDI wirings.
If you are on AUM TestFlight please try out Mela 4.2 with AUM 1.4.5 and let me know if it’s all working as expected.
AcoustiMan
Nikolozi: 🙏
AcoustiMan
Nikolozi: Fortunately AUM version 1.4.5 is finally released. That gave me the opportunity to test the loading of the AU-parameters and the midi-mapping. It works fine for 8 instances of Mela 4 each with different modules. But with more Mela-instances AU-parameters are not loaded correctly again when opening an AUM-project.
Nikolozi
AcoustiMan: ah that sucks. I'm not too surprised because the hack was based on timing and if a project takes longer to load it could mean timing changes. Apple has confirmed that bug and I'm hoping they fixed it in iOS 17. I'll test it tomorrow when it comes out. Otherwise, I'll have to see if the hack can be improved until Apple fixes the bug.
AcoustiMan
Nikolozi:in the meantime I use a workaround with an auv3 plugin called Midi-messenger. With this plugin I can automatically load a saved Mela-preset when loading a AUM-session.