validate-audiounit

AudioUnit Validation (auval)

Plugin Install Locations

AudioUnits must be registered with the system for auval to find them — it does not accept a file path.

AUv2 (.component)

Location	Scope
~/Library/Audio/Plug-Ins/Components/	Current user only
/Library/Audio/Plug-Ins/Components/	All users (requires admin)

After installing or rebuilding, force a rescan: killall -9 AudioComponentRegistrar

AUv3 (.appex)

AUv3 AudioUnits are app extensions (.appex) embedded inside a host .app bundle (e.g., MyApp.app/Contents/PlugIns/MyAU.appex). The host app must be run at least once to register the extension with the system via pluginkit.

# Check if an AUv3 is registered (match by bundle ID)
pluginkit -m -v -p <bundle-id>

# List all registered AudioUnit extensions
pluginkit -m -v -A

# Manually register an appex
pluginkit -a <path-to-appex>

# Unregister an appex
pluginkit -r <path-to-appex>

# Dump full extension info for debugging
pluginkit -e -v -i <bundle-id>

After rebuilding, re-run the host app or use pluginkit -a to re-register the updated extension.

Instructions

1. Register the plugin with the system:
   • AUv2: Install the .component in a standard Components location (see above)
   • AUv3: Run the host .app at least once, or manually register with pluginkit -a <path-to-appex>
2. Identify the plugin's AU type (aufx, aumu, etc.), four-character subtype, and manufacturer code
3. Force a rescan if the plugin was just built: killall -9 AudioComponentRegistrar
4. Run: auval -v <type> <subtype> <manufacturer> — this works the same for both AUv2 and AUv3 once registered
5. Check the final line — * * * * * * * * means all tests passed
6. If tests fail, see Common Issues below

Basic Usage

# Validate an effect (aufx)
auval -v aufx <subtype> <manufacturer>

# Validate an instrument (aumu)
auval -v aumu <subtype> <manufacturer>

# Validate a MIDI-controlled effect (aumf)
auval -v aumf <subtype> <manufacturer>

# Validate a MIDI processor (aumi)
auval -v aumi <subtype> <manufacturer>

Listing AudioUnits

# List all registered AudioUnits
auval -a

# List all AUs with their file locations
auval -al

# List AUs without instantiating them (faster)
auval -l

# List all effects
auval -s aufx

# List all instruments
auval -s aumu

AudioUnit Types

Type	Description	Example
aufx	Effect	Gain, EQ, Reverb
aumu	Music Device (Instrument)	Synth, Sampler
aumf	Music Effect (MIDI-controlled)	Arpeggiator with audio
aumi	MIDI Processor	MIDI filter, transposer
aufc	Format Converter	Sample rate converter
auou	Output	Audio output
aupn	Panner	Surround panner
augn	Generator	Noise generator

Validation Options

# Basic open/initialize test only (fast, good for debugging)
auval -o -v aufx <subtype> <manufacturer>

# Run with stress test (multi-thread test for race conditions, default 600s)
auval -stress -v aufx <subtype> <manufacturer>

# Run stress test with custom duration (in simulated seconds)
auval -stress 120 -v aufx <subtype> <manufacturer>

# Run with real-time safety test (requires sudo, uses dtrace)
sudo auval -real-time-safety -v aufx <subtype> <manufacturer>

# Repeat validation N times (catches open/init bugs)
auval -r 5 -v aufx <subtype> <manufacturer>

# Stop on first error (useful for debugging)
auval -de -v aufx <subtype> <manufacturer>

# Stop on first warning (stricter)
auval -dw -v aufx <subtype> <manufacturer>

# Quiet mode (errors/warnings only)
auval -q -v aufx <subtype> <manufacturer>

# Quiet mode suppressing parameter/factory preset info
auval -qp -v aufx <subtype> <manufacturer>

# Wait after finish (for memory profiling with 'leaks' tool)
auval -w -v aufx <subtype> <manufacturer>

# Load AudioUnit out-of-process
auval -oop -v aufx <subtype> <manufacturer>

# Open as component (not plugin)
auval -comp -v aufx <subtype> <manufacturer>

Strict Options

Strict options enforce checks that would otherwise only produce warnings. Use -strict to enable all strict checks — this should be used by default for thorough validation.

# Enable all strict checks (recommended)
auval -strict -v aufx <subtype> <manufacturer>

# Individual strict options:
# Enforce AudioUnitScheduleParameter output check (always enforced since Leopard)
auval -strict_SP -v aufx <subtype> <manufacturer>

# Enforce parameter default values fall between min and max
auval -strict_DefP -v aufx <subtype> <manufacturer>

# Require conformant kAudioUnitProperty_CPULoad implementation (if in use)
auval -strict_CPUL -v aufx <subtype> <manufacturer>

Batch Validation

# Validate all AUs of a given type from one manufacturer
auval -vt aufx <manufacturer>

# Continue on error in batch/repeat mode (don't stop at first failure)
auval -c -vt aufx <manufacturer>

# Run commands from a file (one command per line)
auval -f /path/to/commands.txt

If no options are given, auval looks for a file called auv-autorun.txt in the launch directory or /tmp/ and runs commands from it.

Component ID Formats

Component IDs can be specified as 4-char codes or 8-digit hex values. These are equivalent:

auval -v aufx bpas appl
auval -v 61756678 62706173 6170706C

The two formats can be mixed freely.

Return Codes

Code	Meaning
0	OK — all tests passed
-1	AU failed validation
1	General error
2	Fatal error
4	Unauthorized (open)
5	Unauthorized (init)

Memory Leak Testing

# Start auval with leak detection
export MallocStackLogging=1
auval -v aufx <subtype> <manufacturer> -w -q

# In another terminal, find the PID and check for leaks
ps axc | awk '{if ($5=="auvaltool") print $1}'
leaks <PID>

AUv2 vs AUv3 Conflicts

AudioUnit v2 and v3 plugins are identified by their type+subtype+manufacturer code. If both formats are registered with the same codes, the system will prefer one (typically AUv3), which can cause confusion during development.

Best Practice: Use different subtypes for AUv2 and AUv3 during development. Most build systems (JUCE, iPlug2, iPlug3, etc.) provide separate configuration fields for AUv2 and AUv3 subtypes.

To temporarily remove an AUv3 so the AUv2 is used instead: pluginkit -r <path-to-appex>

Force AU Rescan

# Kill the registration daemon to force rescan
killall -9 AudioComponentRegistrar

# Wait a moment, then list AUs
sleep 2
auval -a

Common Issues

AU Not Found

FATAL ERROR: didn't find the component

• Verify plugin is in a standard location (see Plugin Install Locations above)
• Rescan: killall -9 AudioComponentRegistrar
• Check Info.plist for correct type/subtype/manufacturer
• AUv3: Ensure the host app was run at least once, verify registration with pluginkit -m -v -p <bundle-id>, and re-register with pluginkit -a <path-to-appex> if needed

Class Collision Warning

objc: Class XYZ is implemented in both...

• Each plugin must have unique Objective-C class names
• Use your build system's support for unique class name prefixes