Trying to figure out how to debug an Audio Unit plugin problem. After an AU plugin is built, it gets copied to ~/Library/Audio/Plug-Ins/Components. Then some of the time auval (the AudioUnit validation utility) will report that it is present and working and other times it just ignores it. The question is when it is ignored by auval, how is it possible to find out what is wrong or what is the underlying error? There does not appear to be any feedback available for diagnosing AU install problems. Sometimes it is a simple problem like the binary name is incorrect, or there is some other misconfiguration in the Info.plist of the Audio Unit component bundle.
An alternative question is how does MacOS or auval even decide to recognize that an AudioUnit plugin is available? There seems to be some kind of magic going on in MacOS that happens when a plugin is simply copied into ~/Library/Audio/Plug-Ins/Components. Alternatively, if a plugin bundle is manually edited once it is in place in ~/Library/Audio/Plug-Ins/Components for example changing the AudioComponents/subtype in Info.plist, then the change is not recognized by auval utility. It appears there is some kind of internal caching in MacOS does not get updated by an in place edit, but only rather when there is an actual file or directory copy operation.
Any debugging advice appreciated!
