Appendix: Audio Unit Class Hierarchy
This appendix describes the Core Audio SDK audio unit class hierarchy, including starting points for common types of audio units.
Core Audio SDK Audio Unit Class Hierarchy
The following figure illustrates the main classes and class relationships in the Core Audio SDK audio unit class hierarchy, for Core Audio SDK v1.4.3.

Starting Points for Common Audio Units
- For general, n-to-m channel effect units, start with the - AUBaseclass
- For n-to-n channel effect units, which map each input channel to a corresponding output channel, start with the - AUEffectBaseclass
- For monotimbral instrument units (either monophonic or polyphonic), start with the - AUMonotimbralInstrumentBaseclass
- For multitimbral instrument units, start with the - AUMultitimbralInstrumentBaseclass
- For format converter or generator audio units, start with the - AUBaseclass
- For music effect units, start with the - AUMIDIEffectBaseclass
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