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Helpful articles for Final Cut Pro for Mac, Final Cut Pro for iPad and Final Cut Camera:
iMac m4, Sequoia 15.11. When I use send to Compressor from FCP the project hangs with a message Incompatible Audio Units found. Apple:AULowShelfFilter and AUMultibandCompressor. I can't find them in any of the libraries. Doesn't happen if I use Share in FCP. Here is the message. If I click on OK, it works one time. Apple knows where these are, but I don't. Irritating for sure. Come on Apple!
iMac 24″, macOS 15.1
Glad that worked for you. Perhaps those AU plugins are being deprecated. Your FCP and Compressor are updated to the latest versions?
You should send this to FCP Feedback. Final Cut Pro->Provide Final Cut Pro Feedback... or use this link Feedback - Final Cut Pro - Apple
Those AU plugins appear to be wrappers for classes in the MacOS Audio Toolbox framework: Audio Toolbox | Apple Developer Documentation
Flexo is the main FCP private framework and that is what validates the AU plugins and calls them. I believe many of the private frameworks such as Flexo are shared between FCP, Compressor and Motion.
There are many validation checks in Flexo to ensure the AU plugin is the right version and has the right characteristics such as channel config.
We definitely need to know the specific version of FCP and Compressor he's running.
I think there are similarly-named plugins for Logic Pro. There is a procedure to make those effects visible to FCP. If FCP and Compressor were updated but Logic was not updated, yet he's using the Logic version of those two plugins, that might cause it.
Or it could be as simple as FCP was updated and Compressor was not.
I believe I have the latest versions. Show up when I start the programs--FCP 11.0 and Compressor 4.9. I just ran these two and got the same message. These AU plugins are hiding somewhere on my new Mac. I have never used Logic. As I moved apps to my new Mac it may be an earlier version was hanging around on a backup disk. Obvious Flexo is finding the plugins it doesn't like, but I haven't found them.
When you moved apps to your new Mac it may have copied over AU cache files from a prior MacOS version. If so that's an example of why it's best to perform a clean install of apps and plugins from scratch on a new machine.
Use Terminal’s auval -a | grep -i "LowShelfFilter\|MultibandCompressor" to confirm exactly where the system is loading these from.
On my machine running FCP 11.0, Compressor 4.9 and MacOS 15.2, it gives this output. If yours does not say this, post what it returns:
aufx lshf appl - Apple: AULowShelfFilter
aufx mcmp appl - Apple: AUMultibandCompressor
In Finder go to ~/Library/Caches/AudioUnitCache/ and remove any *.cache files inside.
Reboot your Mac, which restarts the audio daemon process.
Launch FCP and Compressor. On the first startup after clearing caches, the system re-validates the Audio Units. Check if the error persists.
If it still happens, use these terminal commands to individually validate those two MacOS AU plugins. Save the output and inspect for any validation or other errors:
auval -v aufx lshf appl
auval -v aufx mcmp appl
However, the above MacOS commands are generic. The FCP/Compressor validation checks run by the "Flexo" private framework are much more detailed. That could potentially include concurrency constraints, channel format support, sample-rate compatibility, or specific flags that are unique to FCP or Motion. That is really good because a buggy or wrong-version MacOS system plugin could destabilize FCP or Compressor. OTOH it's possible auval could pass yet the Flexo AU validation checks could fail. So the above are just attempts to find the problem source, they are not guarantees.
Does the error happen if you create a Compressor Share Destination and then Share using this instead of Send to Compressor? Create share destinations in Final Cut Pro for Mac - Apple Support
The error does not show up when using a Share Destination, so that is a good workaround. Thanks.
Final Cut Pro Compressor stalls Incompatible Audio Units found
