|This page describes support for Audio Unit effect plug-ins in Audacity. Audio Units is a plug-in architecture developed by Apple and is only supported in Audacity on Mac OS X.
Audio Unit support
Audacity scans for available AU plug-ins each time it launches. AU support is enabled by default, but it can be turned on or off by clickingthen under "Enable Effects", uncheck "Audio Unit". Restart Audacity for changes to take effect.
Audio Unit "MusicEffects" are supported. This class of Audio Unit supports audio input like pure "Effect" AU's but has the ability to use MIDI input to set effect parameters. Audacity doesn't yet accept MIDI input, so although MusicEffects should work fine as audio effects, parameters need to be set manually. Examples of MusicEffects are all those from DestroyFX, Ohm Force and SFXmachine, plus FXpansion Snippet, Tobybear MadShifta and u-he MFM2.
Like VST plug-ins in Audacity, Audio Units display their full GUI interface by default, where one is provided. If interface difficulties arise, Audio Units can be limited to a tabular interface with sliders by unchecking the option "Display Audio Unit effects in graphical mode" at . Once again, restart Audacity for changes to take effect.
For instructions on how to load new Audio Units effects into Audacity please see this page in the Manual.
Antares Auto-Tune Evo
This plug-in only has a tabular interface which is apparently a problem in some other Audio Unit hosts also.
Apple AU GraphicEQ
AU GraphicEQ has an inherent limitation that it cannot be resized in use, so that if more bands are selected than fit on the screen, not all the selected bands will be accessible. As a workaround, close the plug-in with the required number of bands selected, then re-open it. All the selected bands will now be accessible.
Apple AU MatrixReverb
AU MatrixReverb only outputs in stereo and needs a stereo track to work on, so cannot be used on a mono track. It seems to be the only one of the built-in Audio Units plug-ins that has this limitation. For a workaround, select the track by clicking in its Track Control Panel above the Mute/Solo buttons, then. Click on the dropdown arrow in the Track Control Panel of the upper track > . After processing with AU MatrixReverb, click the arrow again > , click the arrow once more in the upper track and make it Mono, then delete the lower track by clicking on the [X] in the Track Control Panel.
Prior to Audacity 2.0.5, Audacity loaded all detected AU plug-ins on launch. This could cause Audacity to take several minutes to launch or to be slow to quit if older AU plug-ins were found or if the user had a large number of AU plug-ins. Audacity 2.0.5 onwards only loads detected AU plug-ins when they are requested from the Effect Menu, so if you experience slow launch or slow quit, upgrade to the latest Audacity version from http://web.audacityteam.org/download/mac.
Crash when effect is launched from Effect Menu
If Audacity crashes when an Audio Unit is launched from the Effect Menu, you can move the offending plug-in from <Your Home>/Library/Audio/Plug-Ins/Components or /Library/Audio/Plug-Ins/Components then restart Audacity. Alternatively after restart you can disable all AU effects in Audacity in the Effects Preferences, then restart Audacity once more.
In the unlikely event that an AU plug-in crashes or hangs Audacity on launch, you can look in the Mac Crash Report to find the AU plug-in that caused the problem. You can capture the crash report if required by clicking in the report, COMMAND + A to select all, then COMMAND + C to copy. Alternatively you can find the crash reports in the system logs. Open Finder, then chooseand type:
If you are on OS X 10.4 or 10.5, type:
Then move the offending plug-ins from the Components folder as above. If you identify any specific AU plug-ins that are problematic in Audacity, please contact our feedback address.
Crash or hang on launch
If crashes or hangs on launch persist after moving individual plug-ins, you can disable all AU support in Audacity by using the audacity.cfg settings file. Force-quit Audacity if it is still running (Option - Command - Esc). In Finder, use ~/Library/Application Support/audacity/. Look in that "audacity" folder for audacity.cfg.then type in
Open audacity.cfg in TextEdit. If Audacity has never quit cleanly, you may need to create audacity.cfg by usingin TextEdit.
To disable Audio Units, edit (or add) an "AudioUnits" entry to audacity.cfg so it looks like this:
If you are creating audacity.cfg from scratch, enter all these lines:
Then save the changes to audacity.cfg and restart Audacity. If Audacity still hangs then the problem could be with VST Plug-ins. If you don't need VST plug-ins in Audacity, you can edit/create audacity.cfg so that VST plug-ins are also disabled:
As of end-September 2014 Audacity will not officially support OS X 10.10 Yosemite when released. Yosemite has a new API called AVAudioUnitComponentManager, written in Cocoa. Audacity does not support Cocoa yet. The new Audio Units API adds features such as tagging of Audio Units and a shareable cached inventory of AU's that may have been created by any application on the system that supports AU's.
First indications in Yosemite Beta are that Apple Audio Units do not appear when clicked on from Audacity's Effect Menu. Some third-party AU's may still work in Audacity.