AU Wrapper issues

Hi there,

following the help topic on AU Wrapper I have managed to compile libauwrapper.a and am trying to bundle a VST3 into an Audio Unit, as per the Again example (public.sdk/source/vst/auwrapper/again). I keep however getting FATAL EROR: OpenAComponent: result: -1,0xFFFFFFFF when running auval for validation.

I have noticed some curious behaviour. The build output folder ends up with both an again_au.bundle (?) and again_au.component. The bundle contains a plist and again_au inside Contents/MacOS and nothing else. The component contains a Contents/Resources folder containing again_au.rsrc and the VST3 plugin inside the plugin.vst3-folder.

The Info.plist file (using audiounitconfig.h to populate values) inside the source folder isn’t reflected in either .bundle or .component making me wonder whether something is missing in the example CMakeLists.txt file. I have manually added it inside the generated component which leads to auval validating the plist, but still failing to open the component. Any leads to what could be missing as Apple’s (spartan) documentation on auval and error codes shrouds things in further mystery… Is there an example again_au.component available somewhere to compare its contents ?

This is on macOS 10.13.6.

I checked it here and I don’t get an again_au.bundle folder just an again_au.component folder when building the SDK.
Did you modify something, then please recheck your modifications.


I am not sure if that could help you but you could try with the jamba framework

You can quickly generate an empty/blank plugin (one command).
Then with one command you configure the build
Then with one command you build the audio unit plugin

You can then examine what you get.

I am not saying use jamba for your plugins (although you are more than welcome to), but it would be a quick way to get a fully functional audio unit plugin built with the vst sdk…


I have modified one thing, and that is source/vst/auwrapper/again/CMakeLists.txt to not include the again project as a dependency, but to point towards a precompiled .vst3 version of again. The reason being that I couldn’t resolve the dependencies when running make from this folder. I must mention that I prefer to run the build on CLI as I find XCode confusing to setup and use another IDE for development, however the nature of CMake should resolve the targets fine.

Perhaps a little more guidance is necessary on how to build the default AUWrapper project as the SDK’s README only provides guidance on how to build the example VST3’s…

I can’t thank you enough. I have followed the example jamba sample gain configuration and applied it to my project successfully without having to alter any of my existing plugin code. I like the fact that you leverage the Steinberg SDK but provide a very user friendly tooling to resolve the very issue I was struggling with.

Really happy to see that it helps. And you also nailed the exact reason why I created Jamba in the first place: you still write a VST plugin but with a lot of tooling and helpers around to make it easier to use. I spent so much time trying to figure out, “how do I do X?” that I decided to turn it into a framework that would be easy to use and hopefully help others (from the announcement blog